How to Recharge Alkaline Batteries

Jodie Weston Jodie Weston  |  Updated: April 15, 2021
How to Recharge Alkaline Batteries

About a month ago, I learned that it was possible not only to test old alkaline batteries to see if they are still are usable but also that, with the right type of charger, you can bring dead batteries back to life and that you can actually recharge alkaline batteries. To be quite honest, I was blown away.

Being a dutiful citizen of the world, when a flashlight, computer mouse or portable electronic gizmo such as a remote control stopped working, I dumped the old batteries into my recycle box and installed some new ones. Of course not being wasteful, I favored the use of rechargeable batteries and was quite proud of my collection of various sized Eneloop batteries which hold their charge for up to three years, even while sitting on the shelf.

First, a quick note on the “tools used” for this project:

Recharged Alkaline Batteries - Backdoor Survival


Do you every get a bug in your bum and decide that nothing will stop you from the mission or task at hand? Well, that was me. I wanted to prove to myself that old alkaline batteries were still usable and further, as Dennis Evers (Preparedness is Fundamental) says, you can have free batteries for life.

The first thing I needed to do was to gather up the gear:

Old “dead” alkaline batteries
Battery tester simple enough to use without a Ph.D. in electronics
Battery charger designed specifically for alkaline batteries
Test gear such as flashlights, remote controls, wireless headphones and more

Simple enough although I did have to purchase the tester and the charge. But more on that later.


For years I have been saving all of my old batteries in a box in the garage, thinking that one of these days I would find someplace to recycle them. Where I live that is easier said than done so the box was pretty darn full which was great because that meant I had a lot of raw material to work with.

Batteries to Recycle

My Box of “Dead” Batteries

While waiting for my battery tester and alkaline charger to arrive, I sorted through the box, weeding out any leakers as well as odd ball batteries such as cell phone and hearing aid batteries. According to Wikipedia, the reason a battery leaks is this:

As batteries discharge — either through usage or gradual self-discharge — the chemistry of the cells changes and some hydrogen gas is generated. This out-gassing increases pressure in the battery. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both. In addition, as the battery ages, its steel outer canister may gradually corrode or rust, which can further contribute to containment failure.

Leaked Battery

Leaked Battery – Yuck

Surprisingly, most of the batteries in my box were clean. Something to keep in mind as you go through the sorting process is that if there is even a single leaker in the box, the residue can spread on to other batteries so it helps to have a rag handy to wipe each battery off to see if it is okay. If you even suspect that a battery has leaked, or if shows any rust or corrosion, don’t take a chance. Throw the baddies back into the recycle box.


I purchased an inexpensive battery tester from Amazon. There was nothing special about it and it was easy to use. Plus, it had the ability to test 9V batteries as well as button batteries and the traditional AA, AAA, C and D sized batteries.

Simple and Cheap Battery Tester

Simple Battery Tester

I then set to work, testing each and every battery in my box. Much to my surprise, there were a number of batteries that tested “fully charged”. It is interesting to note that many were 9 Volt batteries that came out of one of my carbon monoxide detectors. This leads me to believe that the detector is bad and not the batteries.

Furthermore, I now believe that what commonly happens is that, for example, a remote control or flashlight is dead. You dump the batteries into the recycle box and install new ones. Easy peasy. But in truth, perhaps only a single battery of the 2 or 3 are bad so in effect, you are dumping out 1 discharged battery and 2 or 3 perfectly usable batteries. I even proved this myself. Since I now keep one of these $8 testers in my desk drawer, when my wireless mouse died a couple of days ago, I found that only one of the two AAA batteries that I had removed was dead. The other was showing almost a full charge. Go figure.

The other thing, and something that makes me feel careless and stupid, there were some perfectly good rechargeable batteries in the box. Now, how the heck did that happen?

Good Batteries

These were good!

Batteries test fine in the mini MAGLITE

And I thought these batteries were dead.


After reading reviews on various rechargers, I settled on the Maximal Power FC999 Universal Battery Charger. It wasn’t the most expensive available but according to a couple of the reviewers, this unit was exactly the same as a higher priced model. The difference was that this one is black and the other one was gray.

Maximal Power battery charger from Amazon

Maximal Power FC999 Universal Battery

Now here is the deal with this charger. It has four separate charging chambers that operate independently of each other. This means that you can mix and match battery sizes (AA, AAA, C, D) without a problem. It also has a center 9V battery chamber but I have not been able to figure out whether that piggybacks upon one of the adjacent chambers or whether it operates separately.

Note: this charger can also be used to charge Ni-cd and Ni-MH batteries but I only tested it on Alkaline batteries. There is a slider switch that allows you to select the type of batteries you are charging – they can not and should not be mixed and matched by type (although, as I mentioned, various sizes of the same type work just fine.)

There is no question that I experienced a bit of trepidation when I inserted the batteries into the charger for the first time. But there was no smoke and no explosion so I continued on.

A few seconds after you insert the batteries, the tester will recognize the status and the LED window will either say “CHA” (for charging) or “BAD” (for sorry, this is a bad battery and it cannot be charged). In addition, the following lights will glow:

  • Red – Charging
  • Green – Fully Charged
  • Red Flashing – BAD

As I mentioned above, each of the four chambers operates independently so you could have a combination of these three options all going at once.

There is a chart in the manual that indicates that an AAA battery will take 2.5 hours to charge, an AA 5 hours, a C size 6 hours, and a D sized 10 hours. In my experience, however, they charge to the fully-charged, green light stage a lot sooner than that. Now here is the thing. Once fully charged, the charger switches to a trickle charge to keep the battery “at its optimum capacity” whatever that means.

My experience is that if you leave the recharged batteries in the charger overnight – or say for about 10 or 12 hours – you will get a much stronger charge. I say this because I first tested some batteries right after the green light came on. On my tester, they would register at about the half way mark in the fully-charged area. If I put them back in the charger, the green fully-charged light would come on right away but when I took them out the next morning, the tester showed them about 90% charged.

Recharged Alkaline Batteries

These batteries have been re-charged and are now usable

After doing this a few times, I realized that next on my bucket list was a tester that would give me the actual voltage of the re-charged battery. My brother and nephew – both electronics wizards – have one and tell me that is the only way to truly test the remaining juice left in a used battery.


The little manual that came with the charger stated that alkaline batteries can be charged to 75 – 90% of their original capacity. It further said that the batteries should be fully drained before recharging but I found that as a practical matter, the fully drained batteries came up “BAD” and could not be recharged at all.

There is one more rather important note that I want to make. I checked on my recharged batteries about two weeks after storing them in a box in my utility cupboard. Much to my surprise, there were some new leakers. Now whether these were overlooked initially (had I wiped away the residue not realizing they were compromised) or a byproduct of the charging process – I do not know. Even more curious, they were all the Costco Kirkland brand batteries.

Alkaline Battery after recharging

I had good luck charging the Duracell batteries

The manual also indicates that alkaline batteries should not be recharged more than 30 times. 30 times – holy moly – that seems like a lot of charging to me. For now, I will charge them once until I go through the pile and then start anew. But 30 times? I am going to play it safe and protect my devices by recharging no more than a dozen times if that.


Using the recharged batteries on low power devices such as mini LED flashlights and of course, my computer mouse, worked great. As a matter of fact, I can not tell the difference between the recharged Alkalines and standard rechargeables. On the other hand, the Survival Husband uses wireless headphones to watch TV and the recharged alkalines only last abut 8 hours as opposed to the typical 15 to 20 hours with standard Ni-mh rechargeables.

flameless candle

Flameless candles have burned steadily for 5 days

The recharged 9V battery worked especially well on my little Blocklite flashlight. This little flashlight has been on 24/7 since March 9th and today for the first time I noticed the LEDs starting to fade when all six LEDs are on. When I turn the switch to 2 LED mod, it is as bright as ever.

blocklite flashlight

Blocklite Mini Flashlight in Day 7

Clearly, for now, at least, it appears that the recharged alkaline batteries are best suited for low-drain devices.


I purchased these inexpensive storage cases for my recharged batteries. They are really quite handy and I like that the six individual cases interlock and connect together to make a larger case. The rest of my spares are in the plastic pencil case you see pictured above.

Battery Case 002

I like these mini storage cases.


For a total investment of about $34, I now have what for all intents and purposes, a lifetime of free batteries. The reason I say “lifetime” is that my friends have indicated a willingness to give me all of their dead batteries and you can bet that many will still be either good as is or eligible for recharging.

Would I trust these recycled batteries in a survival situation – sure, if that is all I had, But of course, that is not the case. I still have a large supply of brand new alkaline batteries in all sizes plus a good supply of standard rechargeables (you know how I love those Eneloop rechargeables).

But as spare batteries to use day to day, heck, these are great. As my tests have proven, a recharged alkaline battery can keep a small LED flashlight going to over a week and a computer mouse for much longer than that. As a matter of fact, you might say I have become obsessed with using these recharged alkaline batteries. But that, of course, is a story for another time.

Additional Resource: If you also want to create the ultimate battery charging batteries with different power sources and methods, check out this resource on the best charging set-ups.

Bargain Bin: Here are links to the products mentioned in today’s article. I do hope you will consider the battery tester – it will definitely pay for itself by preventing you from recycling perfectly usable alkaline batteries.

Maximal Power FC999 Universal Battery Charger: This nicely built charger will charge AA, AAA, C, D, N, 9V, Ni-MH, Ni-CD, and Alkaline batteries. It has an LED display so that when you first put a battery in the charging bay, you know whether it is viable for charging or simply bad and ready to go back to the recycle box. Note: When I purchased the charger, it was on back order. Oddly, it actually shipped the next day. Go figure. Anyway, I am really sold on this charger and can recommend it without reservation.

Blocklite 001

Blocklite Mini Compact Size Ultra Bright 9V LED Flashlight: One of my readers (James) turned me on to these nifty little LED flashlights. They were great with re-charged 9V batteries. There is a similar flashlight called the Pak-Lite (which is more expensive) but it does not have a high-low switch like this one.

SE BT20 9-Volt Battery Tester You definitely should consider a battery tester even if you decide not to re-charge your alkalines. The advantage of having a tester is that when a gizmo dies, you can determine whether just a single battery is discharged and not the complete set.

SODIAL(TM) Battery Tester Volt Checker for 9V 1.5V and AA AAA Cell Batteries: This tester has a numeric display – something worth considering although may take two to three weeks to arrive.

AA / AAA 4 Cell Battery Storage Case (Bundle of Six Cases): I like these little cases. I put a sticker on the outside of the case indicating that these are re-charged batteries.

And for traditional rechargeable batteries:

Solar 11-in-1 Battery Charger: This is a universal charger that does what it is supposed to do. It uses sunlight to generate a current that charges pairs of batteries in sizes AAA, AA, C, or D and works great with my favorite Eneloop batteries.

Sanyo Eneloop 1500 Super Power Pack: This kit has it all, including 12 AA, 4 AAA, 2 C and D Spacers, a 4 position charger and storage case. This is the kit that I own.


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139 Responses to “How to Recharge Alkaline Batteries”

  1. Wow! What a great idea on the batteries! Like you, I also had a recycle battery box that made it’s way to our local recycle center. I am going to give this a try. I didn’t even know they made a charger that recharged regular batteries.

    • Alert huge discovery….if you recharge a half charged alkaline battery using a 12 volt 10 watt Solar mini panel the batteries hold a better charge…never fully discharge the alkaline batteries. No leaking as of yet. I recharged 2 AA batteries that were half full 1.32 volts…new they are 1.59 volts. After 8 hours of sunlight the batteries where 1.73 volts and no leakage.

      You do not even need a charger just the mini solar panel wire them up in series. I recommend putting 4 AA batteries in series on the 12 volt solar panel.

    • Where can a purchase this solar charger, and can you post a diagram if how you write them up? Thank you, sounds like the way to go..

    • Home Depot sells a nice solar charger 12 volt 2 watt

      Get a cheap volt meter from harbor freight if bat is not charging up swap wires
      Aaa and aa no more than 1.59 volts
      Have fun it really works…

      The Suns power is do not act like what comes out of you wall plug

      No leaking …slow solar charging is the way to go and it’s free

    • I wonder what the cost of the electricity used in charging might be. Also, how much time did he spend doing this little experiment.
      Other than those two items, good job!

    • this unit is powered by12v dc. it can be powered by your car or 12V dc solar set up. you will have to change the power cable to match where your getting the power.

    • I’ve been using the Maximal FC999 Mark 11 now for a year! I’ve recharged 1,000’s of Alkalines: a3 A2, C, D, 9 V.- I’ve opened up a tiny business a few months ago. I’ve now earned enough to cover the costs of the Maximal. 20% of batteries are really throw aways, 40% are at 90 – 100% power. The remaining 40%, I simply recharge and sell for 50C – 1.00$

    • Yes it does. It also tests those pricey button batteries. You can not recharge the button batteries but you can find “good” ones that are still usable in the recycle box (or at least I did).

  2. gaye: one thing i notice is the random organization of batteries in your larger boxes. please be aware that batteries with any charge left in them can be a fire hazard if they complete a circuit. this can happen especially with 9-volt batteries that come in contact with something metal, like a paperclip. i’ve seen news stories where people’s junk drawers spontaneously burst into flames because of spare batteries touching metal. you are best to organize your spare batteries (recharged or for recycling) into rows all facing the same direction, and with a piece of cardboard between each layer. something like this photo. just wanted to share with you. //

    • Thank you so much for this advice. As I was pondering why a few had started to leak – I mentioned this in the article – I began to wonder if it had something to do with the way they were being stored. I need to get some more of those little battery cases that I like so much. In the meantime, I have taken them out of the box and laid them out on a towel with nothing touching. Thanks again. I plan to pass this info on to my readers in the Sunday Buzz as well.

    • you can still keep them in cardboard boxes (no metal), i just suggest keeping them all facing the same direction and layers or rows separated by more cardboard. don’t know if this has any effect on the corrosion/leaking or not. other suggestions for inexpensive storage are tackle trays, sewing or drawer organizers with little compartments. i personally like small cardboard boxes, shoeboxes, etc, because they’re free and stack easily.

    • You can also put a piece of tape (I use duct tape) over the contact ends so they can’t touch metal and short across to start a fire. This is for 9 volt batteries which are usually the culprits that start fires but it will work on all.

    • It is best to use electrical tape on the ends! I’ve read many articles that suggest only electrical tape to be used!

    • This was the first thing I thought as I saw that picture of that box of batteries. “WOW what a fire hazard!” Seems Gaye caught it, either from you or when she noticed the pic in her article. Sometimes a photo clicks something within us which gives us an extra perception. 😉

    • I store my batteries using slits of bycycle rubber intertubes cut into 3/8 slits ( you can get hundreds from a single innertube) to cover button type batteries. This will help from creating a circuit. Just find the right size innertube and stretch over battery. They dont come off in your pocket as well. Thrift store or failed innertubes can be repurposed.

  3. Thanks for the info. Have not come across these issues yet but I am living off grid for last 6 years and have solar system with L-16 battery bank. Will be back often for more great information. Thanks George

  4. thank you for an excellent well written,well thought out, useful article, to take it a step further, any thoughts on solar chargers?

    • I am in the process of testing a compact solar charger for my electronic devices (cell phone, computer and iPad) but so far the sun is not cooperating. I have not used a solar battery charger yet for the same reason but will add that to the bucket list for later in the Spring.

    • I got a 12 volt solar panel a small one 4″ x 14″ on eBay for $19.99 I use it as a power supply for my alkaline battery charger…so far so good. It takes about 2 days to recharge 4 each AA batteries…they work like new most of them anyways…it puts out about 19 volts DC the wall outlet use to put out 6 volts AC….

      The solar DC seems to work better IMHO.

  5. Let me know how it goes. Currently I am charging all of my phones, screwguns, etc from the wall outlet that is fed by the six 225 watt panels that power my frig and all other electrical appliances in my home. When I climb 14,000 foot peaks I could definitely use a portable charger. Thanks for your info. I will be waiting anxiously for your next report. Please give me brand info on your results.
    Thank you

  6. Hello to all who are recharging alkaline batteries.
    As a knowledgeable electronic type I want to put a little “professional” spin on the battery situation. The fact that you have worked out a recharging program is good. The first thing I want to say is the recharged batteries may not have the same power capacity they did when brand new. Each time one is successfully recharged it will loose a bit more available power. They won’t last or recharge forever.
    One poster mentioned the fire hazard of storing loose batteries. Yes keep them all lined up in the same direction with the cardboard spacers. 9 Volt batteries are the most dangerous to store loose. Put a piece of black electric tape over the terminals. If you bought the batteries in one of those 24 or 48 packs that would be a good place to restore them. One last comment a recharging battery could vent with some force so don’t have the charger located where it could cause harm.

    • Thanks for your insight, Bill. I have already reboxed my charged up batteries so they all line up in the same direction. I chose to only use one layer per box just to be on the safe side.

      Good tip regarding the electrical tape – I plan to share you tips on an upcoming Sunday Survival Buzz.

    • Thanks for that last comment. I’m currently using my charger. I’ll be rehoming it as I leave this site. 🙂 Gaye, this charger works great and like you, I told people I would take their old batteries off their hands. lol I so love the looks! Thanks again Bill.

  7. Wow, that is really interesting. Thank you so much for posting this. I had always thought that it should be possible, somehow, to re-charge batteries, even just the normal ones.
    Leaky fluid from batteries kind of scares me. I don’t know exactly why… it just seems like poisonous, disgusting chemical something. I think I’ll stay away from the Costco Kirkland batteries.

  8. I use a Burgess battery charger for NiCD and carbon-zinc batteries. It will charge 9 volt batteries in about 5 hours. I have been using it on 9 volt carbon-zinc batteries for smoke detectors and it works fine. I check the voltage on the charger with my volt meter and it showed that it was only charging at about 1 volt. So far all of the 9 volt zinc-carbon batteries work fine in the smoke detectors. Now I wait until one start beeping and switch in 9 volt from my stockpile and recharge the old one. Much better than buying 9 volt batteries once a year. I do not know how many times the carbon-zinc 9v batteries can be recharged but I have a bunch.

  9. Instead of purchasing specific type battery testers you might think about a voltage meter. You can get those at Wal-mart, Dollar General, Harbor Freight or about any place that sells tools, but these are the least expensive with a cost under $5. A voltmeter can not only test the voltage of any battery, but household voltage, test for shorts and more. I have found that certain irregular batteries like button type or a short AA called 2/3 AA, can be charged using some type of conductive material like a screw or bolt of the proper length to fill the space in the charger.

    • Yes but a volt meter (multitmeter) by itself places minimal load on the battery cell. The testers illustrated do draw a moderate amount of power (current) from the cell under test. A four ohm load, on my one. Giving a better indication of the overall health of the cell.

  10. So I did go ahead and buy the Burgess Battery Charger and proceeded to recharge the coffee can full of dead AA and AAA. Everything looks good – the charge meter I bought says they are recharged. I stored the re-charged batteries in empty plastic pill containers. I went to use some the other day and there was some kind of clear fluid leaking from the batteries – I checked all the containiers I had, 5, and they all had the same clear, viscus fluid coming from the batteriers. I dont know if all the batteries were leaking of not. Needless to say I did not and will not use the batteries in any of my electronics. Has anyone else had this happen after recharging alkaline batteries? Needless to say I will not try recharging alkaline batteries again.

    • Prepperdaddy – The only problem I have had is with the Costco Kirkland brand batteries. They are leaking some sort of white powder stuff and so I have not used them (nor will I purchase them again). This has happened to me with those Costco batteries even without re-charging them. There have been times when I open up my flashlight to change batteries and find that they have leaked inside making a big mess. I was glad they were not in my expensive electronics.

      BTW, in my more expensive devices I still use the Sanyo Eneloop rechargables – those are the best.

      Another thing is that my charger is a Maximal Power and not a Burgess.

      You do have me wondering if all of your batteries were of a single brand. Other than the Costco brand, I have had no additional leakers. The Duracells seem to hold the charge the longest but that may simply be my perception.

  11. Hi Gaye…

    I was wrong about the charger, I checked my old orders on Amazon and I did get the Maximal Power FC999. I also buy all by batteries at Costco but I don’t get the Kirkland brand…I get the other name brand they sell…is it Energizer??? In any event, it was the ‘good’ brand that was leaking some kind of goo from the bottom of the battery. I will be buying some good quality rechargeable from now on…the Eneloop look good. Thanks…nice to know you don’t write once and forget. Tell your good friend George that if he wants to stop his Gout, he needs to eat a Fat Free Yougurt every morning..he wont listen to me..:-)

  12. What type of charger are you using, I have been told you can’t use NiCad battery charger to charge alkaline batteries.

  13. Under the “Bargain Bin” above she lists the Maximal Power FC999 Universal Battery Charger with a link to it on Amazon. You can find the same or similar elsewhere, just do a search for “alkaline battery charger”.

  14. A couple of years ago I bought the Rosewill RGD-CT505 Battery Charger for AAA/AA Alkaline and Ni-MH Batteries on Amazon. I’ve got a battery tester I bought years ago from Radio Shack. My experience has been that the top quality brands of alkalines charge better and hold their charges longer, making them a better buy in the long run.

  15. Gaye, I saw a video once about a home being burned from old batteries being stored prior to disposal. The 9 volt battery if still has a charge, which most do, can short out and spark. Most of us know the way to start a fire using a 9 volt battery and steel wool. Well, the same thing can happen when these are stored. I know this has to be the perfect situation, but when I put those in the pile, I take a piece of electrical tape and put over the terminals. Better to be safe than having to replace your home, or worse.
    I also strongly agree with you about Kirkland batteries.

  16. Gayle, I learned about batteries while doing the boating live-aboard thing. All batteries test full after charging; they are now at about 65- 70% full. Leave them on trickle 8-12 more hours, and fill them up. Also, high drain and high charge cause them to leak quicker. You can lacquer seal them to prevent the worst of this. Try clear fingernail polish, and Do Not cover the terminal dots. If you want more info, try the boating battery books.

  17. I also have the Maximal Power and use as for my tester. Yep–the remotes, mouse does only have one dead battery–I imagine I have wasted oodles of money discarding perfectly good batteries.
    Inexpensive charger from Amazon.
    I also have a solar battery charger. Use it often.

  18. Gaye, there is one other battery type in both AA and AAA sizes that is rechargeable — and very interesting because of its slightly higher voltage. (I just tested one at random with a voltmeter at 1.78 vdc.) It’s called a Nickel Zinc battery, and is abbreviated NiZn. Fry’s and Big Lots once carried them, but now I can only find them on eBay and Amazon (made in China). There is a special charger (sorry, not solar) sold just for them. That higher voltage does wonders for some things like pocket flashlights, battery powered shavers, etc. I haven’t found any gadget yet that the slightly higher voltage damages, but there may a surprise some day.

    Thanks for your insightful articles over the years.

  19. Just buy eneloops and do it right,they will safely and reliably recharge for years.They wont leak as essentially all alkalines do eventually.First time you ruin something with a leaking alkaline you will see this isnt the area you want to save pennies in.

    Buy eneloops and be done with battery issues for years.Making them quite cheap in the long run.

    • I agree a THOUSAND percent (if that’s possible LOL). I have had a couple of chargers over the years that purport to charge alkaline batteries. One of them was the one in this article – very informative and well written by the way. BUT I have had enough of them leak, of various brands, to dissuade me from ruining anymore electronics in this endeavor. Incidentally, I had several of them leak after being recharged in this particular charger. I returned it to Amazon a couple of weeks later. I have NEVER had a NiCad or Lithium-Ion battery leak and now use the Eneloop variety exclusively. I’ve been dealing with electronics and charging batteries for many years; trust me – save yourself the headaches and frustration of ruined electronics! In addition, I’ve had “never-recharged” alkalines leak and ruin electronics. The manufacturers used to replace a product ruined by a leaking battery. To my knowledge, this is no longer the case but the leading manufacturers (made in China, of course) will send you a certificate for more of their leaky batteries if you complain.

  20. First, I want to STRONGLY second the comments about not having the charger – OR the newly charged battery – anyplace where fumes, leaks, fire, or a small explosion could create a bigger problem. You are taking a small but nonzero risk of all of these by recharging a battery that was not designed to be recharged. Also, if the battery is even slightly warm to the touch after charging, it could be much hotter internally, and still may leak, vent, or even catch fire for a few minutes afterwards until it cools completely. I’d be wearing gloves and goggles while handling these things, just to be on the safe side. Especially goggles. Burns on skin will heal, but a damaged cornea might not.

    Second, I would strongly advise against ever recharging a 9v battery other than one designed to be recharged. It is different than the others in that it is actually six small 1.5v cells wired in series. Some of these will be weaker than others, and over time, will fail. Recharging it, then using it, can force current to flow through the bad cell in the wrong direction. This is the same reason why you shouldn’t mix old and new batteries in the same device, or batteries of different types.

    Finally, it pays to have a good quality battery tester. To test a battery properly, you need to test the voltage and/or current it provides under load and over some period of time. A weak battery can produce nearly the right voltage without any load, but that voltage will drop dramatically when connected to a load, due to high internal resistance. It also may properly power a load for a short time, but lose power rapidly during that time. Now, some people, realizing this, will just hook an ammeter across the battery terminals. This is a very bad idea because it can damage the battery, causing risks of fire, leakage, even explosion. A proper battery tester should place the battery under a moderate resistive load, leave it there for a period of time, measure the voltage drop initially and over time, and from those measurements, calculate: (a) the internal resistance of the battery and (b) the approximate amount of charge remaining. I don’t know if even a good tester will do this, but I know for sure that a crappy one won’t, and will therefore give misleading or incorrect information at least some part of the time.

    • I’d prefer charging Alkalines on a crank generator designed to charge batteries at a low mA rate to prevent the batteries exploding. You can stop periodically to allow the batteries to absorb the energy. I wouldn’t use the Alkalines in my Maglites or radios but they would offer something if they are able to hold a charge even for a little bit. Rechargeables would be the best for sure, but even some rechargeables burst leak and might even pop causing a fire. They are technically safer though because they are designed for charging while Alkalines can only take in a bit of a charge at a time. Charge them for too long, too high of a voltage/mA or throwing them in any charger is asking for trouble. If you get yourself a hand crank battery charger, you can stop for a little bit and then resume cranking, it stops the battery from heating up and reduce leakage. Batteries that leak like the wiki article states, generally happen from self discharging. Heat is another way the battery leaks, leaving them in your flashlight in the car will generally leak.

    • The batter tester illustrated places a modest load across the cell. About four ohms in my one. A higher resistance across the 9v terminals. This is a reasonable load, and gives a good indication of the cells true state.

  21. Seriously?! 6 hours to recharge a battery that may last 8 hours in a low-demand device? If you want rechargeable batteries, why not just buy some good-quality Ni-Mh’s or Li-On’s? They’ll charge a lot faster; work a lot better; and you won’t be risking a fire every time you charge them! (Actually, the company who makes your charger- MaximalPower- makes great rechargeable batteries- including OEM-replacements for everything from tools to phones, which I have found to perform better than OEM- which is amazing, as most other after-market replacement batteries I’ve tried were junk)

  22. I have found that when my alkaline batteries show BAD on the charger I can usually “jump start them by connecting them to a small solar panel (1.5v), for 20-30 minutes. Then they show up as CHG on the charger and can be charged per normal. I suspect that any low-voltage DC power source would work. Experiment under safe conditions to prevent leakage, explosion, etc.).

  23. Hell, I discovered this fifty years ago when I suspected that the warning was a gimmick to keep you buying the expensive alkalines. Being a junior engineer, I just had to try it. It worked. BTW, I also had to find out why Jello warned us not to put kiwi fruit in their product. (The enzyme in it does not allow Jello to set up.)

  24. Some electronics will register a battery as dead if it is just low. Digital Cameras are a prime example. Once the battery starts loosing charge, it will stop working… when in fact that battery will work fine in other electronics.
    Thank you for a great article, I am on the search now for the charger and reader! We seem to go through a LOT of batteries with 3 kids!

    • Smoke detectors and carbon monoxide detectors are the worse but that is undoubtedly a good thing. I always use new batteries in them and save the recharged 9V batteries for flashlights and other devices.

  25. Gaye
    Great post. Commendable research on your part.
    I just replaced 12 AA batteries tonight in my 6 electronic candles on the family room fireplace mantel. Have to do that every 6 or 8 months or so.
    Also replaced 4 C batteries in my wife’s bedside combination flashlight, florescent light, flashing light and radio. This item rarely used, an emergency device, but needs batteries at least annually. I’m really considering the purchase of the FCC Maximal Power FC999 Universal Battery Charger.
    And then I read Joe’s comments on June 6,14. Being an EE myself, I know he is on target regarding safety. Those without knowledge of the risk involved by deviating from manufacturer’s recommendations for use/handling of electronic devices should not “do this at home”. My suggestion would be to go ahead with your suggestions on recharging batteries. But be careful not to disregard Joe’s comments with regard to safety. Get professional help if in doubt!

  26. Hello great thread with a few paranoid types chipping in LOL ..heres my c cents worth …I us a wireless tail tight set up that requires 4 AA on each Led light ..I went out and bought expensive Nicad energizer batterys the other day and they wont power the lights…why ? heres why Nicad rechargeable only supply 1.2 volts …alkaline toss outs make 1.5 ..I ntend to recharge some as the article tell you how too …NO FEAR …thanks Gaye !!

  27. My 2 cents worth regarding dead batteries appearing not to be dead when checked a while later – Many years ago we were investigating why our new low power parking meter design was actually using a lot less power, but the batteries were not lasting as long as in the older higher power design. After much research we discovered that the pin running from the negative terminal down the inside of the battery appeared to oxidise when there was not enough current being drawn through it. By simply ‘knocking’ the batteries we were able to brake the oxidation layer and the batteries where good for another few months. So there is merit to ‘banging’ your torch when it is dim or putting batteries in the sun to get another life out of them. We never explored the actual science behind the discovery and needless to say the big battery corporations didn’t bother responding when we enquired, so we changed to LiFePO4 rechargeables. So those ‘dead’ batteries are very often only ‘dormant’ and a good knock will ‘wake’ them up.

    • Hendrik – What a fascinating bit of information. I plan to give the “knocking” trick a go the next time my batteries test good but are not functional. I find this happens with one of my carbon monoxide detectors a lot which makes me think the unit and not the batteries are bad.

    • Is that like hitting your fruit tree with a bat several times as hard as you can to “wake it up?” I know it sounds strange but we had a pear tree that wasn’t producing fruit for several years and did this. The next year had fruit.
      Sorry, I know this isn’t about batteries, but it is about “recharging.”
      Ok, maybe I should be “hit” to get recharged. Hhhaaaaa….

  28. Costco batteries are the WORST. I had one explode in my fluke tester, and I had to clean it, and
    glue it back together.

  29. 2 Simple ways to recharge batteries.

    1) Over night
    Fill up a hot water bottle “Yes with hot water” fold it in half with the batteries in the middle of the fold, wrap it up tight in a quilt and leave overnight. FULLY CHARGED.

    2) 5 Min fix
    boil a cup of hot water, place batteries in a mug or cup, get a plastic bag with no holes and place in the mug poor hot water in the bag. Charged Batteries.

    This works 100% just allways check Batteries are not leaking, Iv’e never had any leaks in years of doing this but saftey1st.

    • This does not work….possible batteries may heat up and explode or leak plz do not try this thx

    • I don’t see why it wouldn’t work, you heat the battery by charging it the normal way (With a power supply to charge it +-) which gives it a charge, heating up the chemicals that are inside the battery, storing the energy. It will heat the particles in it doing it this way also, you just need to be careful how hot the water is, it’s just like how much current and volts you are putting through it with the normal DC charge, experiment, but take the necessary safety precautions, that’s the only way to find out.

      Another idea would be putting them\it in a flask to contain the heat and this provides extra safety if they\it were to explode.

    • i spent 10 years of my life in various prisons, in one state you were only allowed an AM radio purchased from the prison store and it ran on D size batteries. we used several methods to recharge batteries so you did not have to buy new ones from the prison store.
      first of place several dead batteries in a sock, then swing the sock really hard to make contact with your enemies face, didnt recharge the batteries but the enemy always went to the hospital.
      but seriously, we would place the batteries near a heat source, even the heat above a floresent light fixture would bring them back to life, not 100% capacity but recharged and saving money just the same.
      another way we hacked batteries was to connect them in series or parallel or even both at the same time to create a battery pack. a bunch of week batteries make 1 kinda ok battery.
      check thrift stores for battery pack holders. “madela” breast pumps sometimes have a battery holder that holds 8 AA batteries to make a 12 volt power source with a plug coming out of it. or you can make your own holder with just some tape and wire.
      the whole jest of the article was that you throw away useable batteries every day. a penny saved is most definately a penny. if you use solar to charge then you have only a 1 time cost. throwing away batteries and buying new ones is built in job security for the retailer. why give your hard earned money away if you do not have to.
      everyone, put your hands in the air, i might have a gun in my pocket and i might not be affraid to use it. now empty the money in your wallets into an envelope and place a stamp of it, then contact me and ill tell you where to send it so it reaches me.
      see how silly it would be to let me rob you of hard earned money? but you do the same thing every day, by forking over hard earned money in exchange for a product that you are going to throw out shortly.

  30. Throwing batteries into a box or bag, etc., may set your house on fire. It has happened. 9 volt batteries are particularly dangerous as the terminals are close together. Shorting the terminals may cause a fire, even if the battery is pretty well discharged.

  31. Thank you for reposting this. It was something that I’ve tried to find a reliable reference for – which item performs best based on someone I trust – and you provided that. Just used your links to purchase all three. Love your site and appreciate all the time and effort you put into giving us such good information.

  32. Just a bit more info, I was making chargers 20 years ago to charge Duracell batteries, the key to stop them overheating and exploding was for every mA put into the battery you had to remove a tenth of it,
    We did this in the UK by using an AC 50hz transformer a Diode and 2 resisters
    Resistors on the plus wave it loaded 200mA and on negative cycle removed 20mA, this method I was able to charge my Casio TV back up as quick as it drained.
    Crude diagram

    • Cute. There is always a sweet spot. I wonder how many cycles they can go through before they finally bite the dust, though.

  33. I have a bunch of yard lights purchased years ago. They
    are solar powered and eventually the NiCad batteries in them
    died. I was given a sack full of Costco AA batteries that came
    out of wireless Microphones which get used for several church
    services then replaced every week as they do not want failures
    during a church service. I put those batteries (kirkland) brand
    in my solar lights and they lasted months to a year … running
    all night and charging all day … not 10 times nor 30 times but
    hundreds of times. I got a free meter from Harbor Freight – it in
    in their ads regularly – actually I have one in every vehicle.
    I sort my free batteries by voltage I am not convinced that this is
    a good test and at a yard sale I bout a little VOM (volt ohm meter)
    for a $1 US that had a special battery test scale. I think that
    this actually puts a load on the battery. 50 years ago when I worked
    on Pilot’s emergency radios and their batteries, I load tested batteries for a specific period of time and then checked the voltages. Low batteries were replaced. We would not want our nation’s defenders out flying around without good emergency equipment.
    I have not had a problem with Kirkland batteries leaking. Many years ago I lived in Portland and I had a source of no cad batteries from
    a warranty repair shop I discovered that those dead C cells in power packs often came back to life if zapped with a jumper cable hooked up
    to a 12 volt battery. It was also almost like an instant charge. Batteries that would not charge in a charger often worked perfect after one or more zaps with a jumper cable hooked up to a 12 volt car battery. Even now I gather recycled batteries from recycle bins and
    recharge them and it has given me many spares for my power tools for free. Ones that do not recharge get an x marked on them and I return them to the recycle box. Free is a very good price for an old man living on Social Security $$$.

  34. I read your article several times. I have two grandsons who go thru batteries over and over. Like you I had a bunch of old dead ones lying around. I decided to try both the Maximal Power FC999 charger and the meter / tester. I had them shipped to me at work. I wanted to test it out. We have a bucket or pail that is full of old dead batteries of all sizes for proper disposal. I picked out 4 AA’s dead by meter test and charged them until they showed OK. Checked them again with the meter. They now show high end of good on the meter. I also found when testing for others to charge there were a lot of batteries that showed good on the meter. And OK in the charger. I have 20 AA that I took home and gave a friend 20 AA’s also. Still charging as I type this. The charger and meter won’t take long to pay for itself at this rate. I keep mining the bucket for AAA, AA, C, and D’s good and those needing charged. The charger only showed 1 battery as BAD so it went back in the bucket. Long story short. Thank you for not only useful information but $$$ savings too.

  35. If they would make one of these a solar unit I would buy one. I think that solar is the only way to go. The sun is always there but the grid probably won’t be.

    • eBay sells many flexible solar chargers cheap….just cut the cord on your charger and wire the solar charger to it…that is what I did works great….it slow charges the batteries so no leaking so far. A new AA reads 1.59 volts, I get about 1.55 volts on a solar recharged battery…2 days of sunlight will charge 4 ea AA batts using my 12 volt solar panel it measures 4″ x 14″ approx. $19.99 on eBay. I have one on my diesel truck as well it keeps the batts full…I use boron and distiller water mix to prolong the life…3 years old now and still reading 14.6 volts. It read 14.3 before I topped it off with the distiller water and boron mix.

    • The boron is a mild acid that prevents sulphides from forming and killing the battery. A low charge allows these sulphides a to form and build up.

      Do not use tap water….it has minerals that build up and kill the battery.

  36. I used a charger that’s suppose to self adjust to the type of battery. Well I had put in two regular batteries one charges so I took it out added another. The other two were almost charged than bam one exploded. I unplugged it fast as I could and cleaned it up after it sat a few. I wont bother doing that again.

    • The Maximal Power charger requires that you move a switch to indicate the battery type (alkaline or rechargeable for example).

      What an awful experience for you. What brand of charger were you using? I was planning to test other brands and want to stay away from any that are problematic.

  37. I have a Battery Master CL 444 battery charger but I lost the power supply module. Do you know what the power requirements are and if so is the center pin + or – ? I searched the internet but was unable to find any information.

  38. I actually just spent a week rotating everything! Now I know what I have and what I need to replace or add more of. It was kind of exhausting. I think I will take a week off of prepping! My kids think I am a slavedriver, and my husband is amazed at what I have managed to accumulate over the last year with the little money we had. Also just put in my order for my garden seeds and plants. Waiting eagerly for spring!

  39. Just this week I saw piece on the local news where you could make an appointment with the local Red Cross to come to your home and check your smoke detectors. A lot of people dont know that smoke detectors are just good for 10 years, then even with good batteries, they wont work. The Red Cross with replace (for free) up to 10 detectors.
    If your smoke detectors are less than 10 years old, remember to change the batteries twice a year. When you turn your clocks forward and back is a good reminder.

    • John R. Your advice is actually the opposite of what this article is about. You recommend wasting money by automatically changing batteries every 6 months without even testing them. Then wasting more money changing smoke detectors every 10 years without testing them either. I have 2 smoke detectors that are over 20 years old and still work and still sound when tested. The batteries last several years without problem. The last time it chirped, I tested both batteries. One was still deep in the good/charged range. The other just barely touched the “low” range. My CO meter purchased new January 2015 just got a new battery in October 2019. I keep written records.

  40. I have been using the standard rechargeable batteries for decades and when you had the article on the Alkaline rechargers some time back I bought one and now keep the Alkaline batteries recharged for many, many more hours of use. I found that the Copper Top Alkaline last the longest and recharge the best, The Bunny not so much. I adapted my Alkaline charger to run off the solar battery system so will be able to charge even in power outages.

    The Eneloops are the best rechargeable ones and well worth the price.

  41. I am active in a coalition against Human Trafficking and this week I donated many boxes of kitchen supplies and food items to 4 young men who had been relocated and were victims of trafficking. I had been concentrating on organizing my storage area so it was quite easy to see exactly what I had stored and could provide to them. It had also given me the push I needed to tame remaining chaos in my basement so I can provide help when needed.

    It has been very cold and snowy in my neck of the woods so I’ve had extra time to hunker down and organize supplies. I’ve also organized articles and clippings on preparedness, survival guides, essential oils and shelf ready cooking into binders so I can actually find things when needed – what a concept!

    Looking forward to Spring!

  42. I just did an inventory of all my preps and listed where everything is stored. Typed up these pages for quick reference. Decided to do this when I was looking for something and searched multiple places till I found it, hate being disorganized! My daughter thinks I’m obsessed 🙂

    • I took it one step further–with 6 BOBs in a room off the garage, it was impossible to get quickly an item if needed, even with the tags identifying what is defense, lighting, etc.
      So I spent a couple hours listing alphabetically the items in all 6 bags.
      Now, easy to find a-z.

  43. Why would anyone remove a drained battery and not recharge-put in recharer, plug in outlet.
    This is pure laziness on steroids.

    • I am sorry you think that is being lazy but so be it. That said, I work 12 to 14 hour days and I am old and exhausted. Your comment was quit hurtful. Gosh, I need my thick skin back!

      Anyway, the whole point was to remind others to keep those batteries topped off and not to brow beat.

    • Yep. You do your level best and you still get hit with cheap shots. I get it. I just want you to know, Gaye, that you get a ten out of ten from me. Peace, my friend. Peace.

    • Q. Why would anyone remove a drained battery and not recharge-put in recharer, plug in outlet?

      A. I seem to recall reading there’s a possibility they can explode if left unattended in a charger. You might not plan be around to pull it out when it’s fully charged back up? You might have other things to do, more important things to do?

      Not everyone follows the ‘one is none’ mantra all the time.

      If you’ve got a solar charger packed away in an EMP-proof container (I don’t)IMHO it’s not really a big deal to put off recharging a battery. A few hours in the dark prolly won’t kill ya. Besides, everyone’s got matches or a lighter if you *really* need to see in the dark.

      The moon often makes for a pretty decent “flashlight”.

      You own a car with working headlights.

      You know your way around your house in the dark.

      Those were just a couple of reasons I could think of off the top of my head. There are probably others besides pure laziness.

      And, sometimes, it’s important to be lazy. To avoid prepper burnout, and all that.

      Anyway, what did I do to prep this week?

      I tested out various wool socks to see which I liked best, there were more differences than I thought.
      Tested some of my extreme Winter gear in sub-zero temps, too.
      Negative -20 degree temps this week, mid 50’s by next week.
      Sounds like next week I get to test some more biking gear.

    • Well said, helot.
      Also, for those of us concerned about EMP, it’s probably best not to have your batteries recharging at the time of an event, so not leaving your batteries in even a fancy trickle charge capable unit is a smart move. NiCd and NiMH batteries are pretty much EMP proof, but not sure what would happen at the time of an event to the charger and what it might do to your rechargeables.
      For non electric light I keep a few container candles around the living room and have matches handy as well. And recently I got another set of UV Paqlites which are really useful as night lights, but can be handy if the power goes out…you just leave them in the sun, or even just under a lamp and when the lights go down (or out) the UV Paqlites start glowing. Not enough to read a book by, but enough to see obstacles in the dark of night.
      Or for Mythbuster fans, try a pirate’s eye patch. 😛 No, seriously, it seems that pirates wore the eye patches for boarding actions…Ever walk into a dark room from bright sunshine? Can’t see much for a while, and that would have been deadly for the pirates, so they kept one eye in the dark (under the patch) so they would be able to see as they went down into the hold and took off the patch, or moved it to the light adjusted eye. Great tip for post SHTF mercenaries. 😉
      In personal prepping news, I bought an AeroGarden Bounty off the ads here and loved it so much when I got an ad for a discounted second unit, I ordered that too! That took care of the last of my Christmas money, but what the heck…fresh salad fixings all winter long is a big morale booster, and not all disasters will involve the loss of the grid (pandemic comes to mind immediately.) Best feature of the new units: LED lights. The old AeroGarden units had fluorescent grow lights that had to be replaced every 4 to 6 months. The LED panels are good for 5 years on these new units! 🙂

  44. On your tip: Prepare Your Family for Survival: Tip #5 If you purchase from They will send you an email when your purchases may be expiring. I purchased from them for one time use for the grandchildren’s first aid kits.

  45. What preps did I do this week? I found you of course!

    I’m generally squared away on most areas (other than being in the ‘wrong’ country – The UK – I’ve tried to emigrate but The INS just ‘giggles’ when they see my application. Sigh!). I have the basics, backups in most areas, and even backups for my backups (I’m ex-forces/ex-nurse so “one is none …” and “Murphy” are rules I’m always aware of, and being single makes things easier, and remains my one major ‘weakness’). But knowledge? I have questions, concerns, clarifications (How do I? Is there a better way? What are all the options?) galore so I spend (probably way too much) time on the web ‘picking other peoples minds’.

    Well, I’ve read Survivalblog (and others for years) and followed a link here, and ….

    I just wish to Thank You for answering questions I had, and even some I hadn’t even thought to ask (and incidentally losing two or three hours of my day when I first found your blog). So keep up the good work! (I now have a file of copied ‘knowledge’, ‘research’ and ‘hard-won experience’ entitled “Gayes Tips” near the front of my library. A ‘go-to guide’ I hope will continue to be expanded for years to come!).

    Oh, and I (guiltily) ‘found’ that I too (despite having three chargers – and a wish, after reading here, for yet another) have a sizeable collection of drained batteries. Sigh! I reassure (excuse?) myself with the thought that “If all your batteries are charged – you probably haven’t got enough batteries” though.

    • Helot

      Hey, laughing is OK, I’m used to it (although generally it’s ladies, and they usually wait until after I ask them for a dance/date first. Sigh!).

      I’m renowned for my sense of humour too. Hardly a day goes by without someone (often complete strangers) approaching to tell me how full of wit I am (at least I ‘think’ it was ‘wit’ they said!).

    • Well, I for one, thoroughly enjoyed your initial post and reply. Welcome and I look forward to your future contributions!

  46. An addition for any who may be interested.

    As you’ll probably have heard the ecig fashion has caused some interest in charging high demand rechargeable batteries. Charging such high-capacity cells could be ‘problematic’ and so there are now ‘charging bags’ available (bags that you enclose your charger in which protects against unwanted ‘side effects’ should the battery vent or explode (they’re available via Amazon of course).

    As capacities of even normal rechargeable batteries increases (I recently purchased some AA’s with a rated capacity of 3200 mAh) it’s always better to be safe than sorry, no? And when mitigating that minor risk is so cheap …

    As an aside, I’ve tried multiple chargers powered via a hand-crank generators (rated at both 1W and 2W output) and all appeared to function fine (solar isn’t really an option in the ‘it’s permanently raining here’ UK), although it’s a ‘lot’ of effort over an extended period (I do ten minutes on, ten off, as and when I can when ‘in the field’). And now trying with normal Alkalines too.


    • No idea how well these will work, but a quick Google search turned up this link:
      Power One Accu Plus rechargeable hearing aid batteries are the only nickel metal hydride (Ni-MH) rechargeable batteries on the market. These quality-made batteries are designed to replace zinc air batteries and must be used with a Power One Accu Plus charger, an exclusive Power One design. The portable Pen Charger charges one NiMH button battery from 2 AAA alkaline batteries for around five hours. The new portable Pocket Card Charger can fully charge two batteries in only two hours. Batteries can be charged more than 600 times on these chargers. Complete instruction manuals accompany all charger models.

  48. i found a product…called mighty Charger you can get it on amazon…it charges regular batteries and it works i have bought 3 of them and i plan to buy a couple more it allows me to use regualr batteries and regarge them…its great for the kids wii i get multiple uses from regualr batties they dont have to be recharables it does aaa aa and 9 volt the thing is great, the first one i had lasted about a year before a couple of the prongs broke, but that was more due to my under 12 children using it than the product it self. i was so happy i bought 2 more and i plan to buy another 6 of them and build a charger box connected to a solar panel the great thing is i can stock up on regular batteries at a fraction of the cost of rechargables…do they last forever no, but an i havent done a hard test but like i said the kids use these in their wii remotes, which suck the power out of them, i also use them for my led flashlights…anyway i get mine on amazon, it think the last time i bought them they were like 15 bucks….was hesitant to pass this along as it might drive up the price and limit availability to my self

  49. I have to agree with the guy about Kirkland batteries. For years,
    Kirkland brand was my go to brand but this past month, I opened up my cabinet to get some batteries and all my Kirklands still in the package were leaking. Then noted that the batteries in my various remotes and flashlights that had failed were also Kirklands. Took the package of bad ones back to Costco and they would not refund me since I didn’t have a receipt for them despite the fact the name Kirkland was printed on the package and the batteries. Was very disappointed in Costco.
    Now, only Duracells for me.

    • I am shocked about Costco not accepting the return without a receipt. When I have a return and there is no receipt, they look the item up in my member sales record and there is never an issue. I refuse to use Kirkland brand batteries for all of the reasons you have stated. They have actually ruined some of my electronics.

  50. Gaye,

    I recently bought one of the Maximal 999 chargers specifically because of its capability to charge alkaline batteries. WOW. With 3 grandkids (plus our own devices) we really eat AA and AAA batteries. We have already been saving some on recharging the alkaline batteries. It even charged an old alkaline I found in a desk drawer that has been discharged for at least 3 years. It charged it up. It does not hold a good charge but that is the battery, not the charger. The alkalines are not as strong as when they were fresh (probably 60%-80% depending on the battery), but for most uses, it is cheaper to recharge an alkaline than buy new ones. Thanks for the recommendation and evaluation.

  51. Interesting and potentially useful blog post. Here is the truth about the process you are promoting here. Non-rechargable batteries are exactly that, non-recgargable. They produce electrical current by a non-reversable chemical reaction. You and others are simply and absolutely not “recharging” them. Your 9th grade chemistry should have passed along the concept that heat is capable of driving, or accelerating a chemical reaction. The “chargers” being employed are merely warming the non-rechargable cells by passing an electrical current through them and driving the last available limited bits of chemical reactants into the one-way, power producing equation. This uses by far more electrical energy that is available in what little chemical is left. This is also why the warming method posted by Mr. Peter Hughes on 5/3/15 works. It is a good technique to remember when nothing else is available, but you run the serious risk of fire, poisoning, chemical burns and destruction of precious electronics or electrical devices as a result. Please use caution, or better yet be prepared with the better alternatives to this risky process.

    • Um…No….completely and utterly wrong. I have recharged these alkalines that you say “cannot be recharged”, and stored them fro months…and still fully charged…. Please, before you go passing yourself off as some kind of “know it all” at least have some reasonable idea about that of which you are speaking. This segment came directly from WIKI…”…As an alkaline battery is discharged, chemicals inside the battery react to create an electric current. However, once the chemicals have reached chemical equilibrium, the reaction stops, and the battery is depleted. By driving a current through the battery in the reverse direction, the equilibrium can be shifted back towards the original reactants. . My point has been made…

    • Some alkaline soil do recharge especially the ones I charge with a 12 volt solar panel 10watt small low power. Slow is the key here so they do not over heat and leak.

  52. Not to do with recharging, but just a suggestion for those of you who are prepper types. I did a 9 month wilderness experiment a couple of years ago and made the mistake of not packing enough AA batteries for my radio, I had plenty of AAA batteries, but AA’s were all gone, I found that by placing an AAA battery negative post down inside a .45 Colt cartridge it makes the AAA fit perfectly inside the battery compartment of the AA powered radio.

  53. Whoa! I think you read the instruction booklet incorrectly or they printed it wrong:

    Rechargeable batteries should be fully drained before charging, NOT ALKALINES!

    Once an alkaline is drained too much, it can never be recharged. You want to recharge alkalines BEFORE they start to show signs of getting weak. In fact, if you charge them regularly, you can get 100+ charges on them.

    As soon as your flashlight dims at all, put the batteries back in the charger and they’ll last for a long long time.

    • NO … the manual was read correctly and that’s what it says. I couldn’t believe what I read (but I did) either. That statement, along with unreliable/believable operation and the leaking batteries that resulted convinced me to return that charger post haste! Incidentally, most modern-type batteries of the rechargeable variety don’t have to be recharged completely as they do not exhibit a “memory” effect. NiCad chemistry must still be fully discharged to eliminate this characteristic, however.

    • “most modern-type batteries of the rechargeable variety don’t have to be recharged completely”

      Sorry … meant to say DISCHARGED completely not recharged

  54. Love this idea. My son’s wireless Xbox controller eats batteries like a hungry hungry hippo. I posted your blog on my timeline and I am considering a post in my own comedy blog about DIY and helpful websites. If I do create that post, I will likely mention this article there as well. Great article and thanks for the WONDERFUL help. I’ll be purchasing the materials to recharge my old batteries today.

  55. I’m totally on board about recharging alkalines. The problem with recharging regular alkalines is they overheat. I use a basic Batteries Plus Nuon branded recharger and a wind-up kitchen timer. Load the charger, set the timer for an hour, plug in the charger, the timer rings, unplug the charger. Repeat when convenient a few hours later when the batteries are room temperature.

    I also use a voltmeter to tell what the real voltage is.

    Eventually I use old batteries in battery clocks, particularly the oldest NiCad / NiMh. It’s normal to get a year out of a charge in a battery that is dead for any other use.

    The same thing goes for mice and TV type remote controls. I didn’t read 100% of your article but I did see “mouse” mentioned, so I apologize if I covered a subject twice. Then again it’s like confirming your information.

    Your subscription pop-up was interesting because it accessed my browser’s SQLite database to populate an email address selection menu. It makes me wonder how intrusive your website is without letting anyone know. Kind of bad form for a prepper.

  56. Love this idea. I always throw away my old batteries. I tend to buy the cheap ones. Buy cheap, buy twice comes to mind…Basically throwing money away as they don’t last long at all. I use loads in my wireless mouse on my laptop. Just replaced them today actually…Coincidence I’m reading this post now…I think not!
    Thanks for sharing. I’m going to try it out.

  57. On youtube I watched a man bring back to life an old dead rechargable drill battery, that would no longer take a charge. He said it worked for big or little batteries like his saw batteries, etc… So I applied the same technique to my little flat square portable house phone battery that had just gone bad, and it worked! This was in mid December of 2015′, and the darned thing is still working. lol
    You take a battery source that is 2x as powerful as the battery you want to revive. I used small wires with clamps on each end that I got, for a few bucks, at Walmart. First you join the negative ends, then, if you are doing rechargeables, like he was, he set the battery in it’s charger, then he attached one end of the positive wire to the good batteries(first he joined the 2 to get 2xs the power needed), then he quickly touched the positive on the dead battery. He said not to leave it on the other battery, just touch it quickly. He did this quite a few times, UNTIL he saw the charge light on the battery charger flicker on for a second, then he stopped. He left the battery in the charger until it took a full charge, good as new. it is supposed to have reset the memory in the battery so that it will not stop working any more, as long as you keep charging it, it should work, not die, as it did before. I am waiting on the one I did, but am already quite pleased with the result. When I did my portable phone battery, it did not have a separate charger to use, so I just kept touching it’s positive end very quickly, until I suddenly got a puff of smoke, and stopped asap! Thought for sure that I had ruined it, but, nope, when I put it back in the phone & on the charger, it said ‘charging’!! And it did. Hope all this makes sense to you.

  58. Hi Gaye, you mentioned your family said you should get a device that measures the actual volts. Is this kind of what you had in mind, or just an actual voltmeter? You said it was next on your bucket list to buy.

    Hapurs Universal Digital Battery Tester Volt Checker for AA AAA C D 9V 1.5V Button Cell BT-168D Batteries
    AstroAI Digital Multimeter with Ohm Volt Amp and Diode Test

  59. Thank you for your article. Currently we are living completely off the grid. Recently we purchased a 45 watt solar system with small inverter. After following your recommendations for charger and tester we are now able to keep a handle on our rechargeable and alkaline

  60. When you recharge batteries from your house electric, what is that cost? Is it less expensive to buy new than to pay the electric bill for the recharging?

  61. The most of our Flashlights have chargeble 18650 Batteries, but we also have some Mini Flashlights with AA and AAA Batteries, So we will try to recharge them, like you do. I am curious, if this is working.

  62. Thank you for this valuable information! I had no idea you could recharge alkaline batteries. I tried to charge a size “D” once when I was a kid – it blew up like a cherry bomb! most of my battery operated things are very efficient and require very infrequent battery replacement, but I have an older GPS that sucks em down at an alarming rate. Wow – I can’t believe how much money I’m gonna be saving now, thanks to you. Keep these great articles coming!

  63. Ive had an alkaline charger similar to the author’s for 3 years. I got mine in the “as seen on TV” section at Wal-greens $20. I HAVE SAVED A WHEELBARROW of money on battery replacement and this article is very accurate on performance. I had never seen a claimed “30 reharges”, at best, i can recharge 3-4 times before the alkalines have no more performance. But all in all, it’s great investment and I have used mine on almost a daily basis! For 3 years! Have had ZERO issues with exploding batteries. Strongly suggest anyone that even jus moderately use alkalines to seek and purchase! I wish i had 5 more of these chargers!

  64. Hi Gayle,

    Thanks for your articles.

    Does the solar battery charger you recommended work with alkaline batteries or only the ac one that you recommended?

    Will my Enloop charger also charge alkalines or does it have to be that particular ac charger you recommended.

    If we click on any link to a product in your article to order on amazon, does that automatically link to you so you get credit for that order?

  65. I stuck some DEAD Energizer Industrial batteries in a Wiimote that I had hooked up to a USB cable to give it power mainly using the dead batteries to hold the 2 wires in place, after a while I noticed the back of the Wiimote was getting hot so I took the batteries out an sure enough they were working again, but as soon as they cooled off they were dead again an wouldnt work.

  66. Just found your site and am really enjoying it!!
    Maybe a dumb question but here goes: can I recharge my alkaline batteries in a charger used for rechargable batteries?

  67. You all may have noticed in some old digital cameras, if you used a rechargeable battery it would say battery low. the reason is that rechargeable batteries have the operating voltage of 1.2vdc and regular non-rechargeables 1.5vdc. you will not find a rechargeable AAA that reads 1.5Volts. So, what confuses me is how a charger that is designed for a 1.2 volt can properly charge a 1.5vdc to full charge. Nate in the comment above said that he connected a 12vdc solar source to six batteries in series at 6X1.5=9vdc so maybe I am splitting Atoms and it is much simpler than that.

    • Maybe the switch used to charge to different types of batteries changes the voltage. Not sure where my volt meter is right now or I would have the answer for you.

  68. I’ve just come back from our recycling centre with another 300 batteries ( a2, A3, C, D, 9V). Likely 50% will test Good / 40% will be low and 10% I’ll trash for corroded terminals. The recommended Maximal Power 11: has recharged at least 1,000 batteries to 90% in the past 6 months! Recharging / reselling is becoming a small business.

  69. This is some really good information about batteries. It is good to know that you should think about storing them properly. That way, they don’t go bad before you can use them.

  70. I bought the same tester and charger several months ago. What a coincidence! Great minds think alike? Both work great, but I only get several days out of the 2 AA’s in the TV remote. No problem, I have plenty more!

  71. Thanks awesome information about batteries! I found this battery reconditioning program: // it show you how to get batteries for free (or dirt cheap), then how to recondition those batteries with a simple new method (so they’re back to “like-new” condition). It also shows you how to (very cheap) build a solar panel’s battery bank using these batteries. I am so grateful that I found it and hope it can help others too.

  72. I’m glad you mentioned not taking the chance if you think a battery has leaked because the chemicals in those are really dangerous. That’s why you’re supposed to dispose of batteries separately from the rest of your garbage. I don’t know where to throw them yet but I’m going to try and find out.

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