Have a Cordless Tool Battery That Won’t Charge? You Can Fix That.

Lithium ion batteries are a wondrous invention that are lightweight and long lasting.  But it’s infuriating when the battery won’t recharge.  You stick the battery in the charger and … nothing.  Guess what? You can fix these batteries that appear to be completely dead.  Read on …

This post is NOT sponsored by Ryobi.  They do not approve of this method.

 

Jump straight to the how to video.

One of two things are going to happen as you read this post.  You will either unfollow me due to my pathological boringness or … you will propose marriage.  So get ready to act accordingly.

If you have any sort of cordless power tool, but especially a Ryobi one, you have no doubt encountered  the dreaded flashing red charger light.  And if you haven’t … you will.  It inevitably goes like this – you run to the basement to grab your cordless drill because after 10 years of thinking about it, you’re finally going to build that 4 level, Tudor style treehouse with kitchenette.   Or you’re going to hang a picture.

Either way you put your battery in the charger and all you get is a flashing red light, which according to the label on the charger means your battery is defective.  It isn’t just dead.  It’s “defective”.  I’m here to tell you you it isn’t.  You probably left it in the charger too long which weirdly drains the battery.

Your battery is fine. It just needs a little boost.

You Can Fix a Rechargeable Battery That Won’t Take a Charge.

You heard me right.  You do NOT have to buy a new $50 battery.  You do not have to call the company and swear at them because this stupid “defective” battery is only 2 weeks old. (although by all means feel free to do so) You do not have to wait until they ship you a replacement battery to finish your project.  You can get that battery up and working in about 5 minutes.

How to Fix a Lithium Ion Battery

What You Need

 

 

AC adapter on workbench.

 

  •  A multimeter.   (this is actually optional but helpful … if you don’t have one don’t worry, you can still fix your battery)

Multimeter on workbench with tools around.


Note:  If you aren’t used to doing this sort of thing, or using things like a “multimeter”  this is going to seem crazy and hard and way out of your DIY league.  It isn’t.  


Steps

Step 1. Cut the end off of your AC adapter.  That’s right.  Just cut it off.  It’s for a 10 year old cell phone, you’re never going to use it again anyway. It’s frankly kind of weird that you saved it to begin with.

Cutting the end plug off of an AC adapter.

 

Step 2. Separate and strip off 1″ of each wire.  You have *just* made booster cables!  Good for you.

Positive and negative wires on AC adapter.


TIP:

Black wire = negative     Striped or solid white wire = positive

IT IS VERY IMPORTANT TO NOT MIX THE TWO UP.  


Step 3. Remove the screws holding the battery together.

 

 

For Ryobi batteries it’s a star shaped screw head like this.

A few years ago I bought a kit of weird small screwdriver heads from Amazon.  I initially bought it because I needed a special tip for removing my Macbook Pro cover to replace the battery.  But I’ve used it for a ton of other stuff since getting this kit.

Tip of star shaped screwdriver.


TIP:

There’s a hidden screw under a piece of plastic.  You need to pry the plastic off to get at the screw underneath. I used a very thin screwdriver to pry it off.


 

 

Step 4. Pull the top off of the battery case.

Top removed from Ryobi Lithium Ion battery.

 

Step 5. Remove the 2 plastic side pieces. They’re the things you press in to remove your battery from your drill.

 

 

Step 6. Lift the battery pack out.

Ryobi battery completely disassembled on workbench.

 

Step 7. Set the Multimeter to read volts.  For testing an 18 volt battery choose the 20 volts setting. This will give you the most accurate reading.  (If you don’t have a multimeter skip to Step 9 and hope for the best)


TIP

Volts are symbolized by a “V” with one or two straight lines over it on a multimeter so it’s that section of the multimeter that you use.  The section under the V with the straight line(s).  Not the squiggly line.  The straight line.


 

Step 8.  Touching the red probe to the positive (red) terminal and the black probe to the negative (black) terminal, read the voltage shown on the multimeter.  In my case the battery was carrying a charge of 0.06 volts.  Which is *almost* nothing, but not completely nothing.

 

Step 9.  Plug your AC adapter in and using the wires, boost your dead battery.  Just touch the black wire to the negative terminal (the one with the black wire going to it) and the white wire (or striped wire) to the positive terminal (the one with the red wire going to it).  Do this on and off for approximately a minute.


TIP

Apparently lithium ion batteries should be “pulse” charged.  Which means you hold your wires down for 15 seconds or so, then release them.  Then hold them down again.  Over and over.

DOUBLE CHECK THAT YOU ARE TOUCHING POSITIVE TO POSITIVE AND NEGATIVE TO NEGATIVE.


 

Step 10. Test your the voltage on your battery pack again.  It should be higher than it was before boosting.  (Again, if you don’t have a multimeter don’t worry about this – you’ll just have to press on without one)

Mine went from 0.06 volts to 7.58 volts after a minute long boosting session.

 

Step 11. Put the plastic cover back on the battery pack (just the part that goes into the charger) and set your battery on the charger to see if it will take a charge.

If you still only get a red flashing light and the battery won’t charge, boost the battery some more. I find the battery charger will recognize that the battery is good again when you boost it to between 10 and 14 volts.

Just keep repeating the “pulse” boosting and testing the battery until it will finally be recognized by the charger and you get the green light.

 

To those of you who found this subject matter to be on par with spending 3 hours in a waiting room, sorry ’bout that.

For the rest of you?  I know exactly how you feel.  I felt the same way. Let me know exactly how elated you were after you brought your first battery back to life in the comments section.

Here’s a 3 minute tutorial video showing me as I fix my own battery.

 

Please direct marriage proposals to my publicist.

→Like to Sweat, Swear and do Stuff? GET MY POSTS emailed to you 3 times a week←

*Proceed with caution and follow instructions exactly. Failing to do so could lead to injury.*

Have a rechargeable tool battery that stopped working? It happens all the time. You put it in the charger and it just won't take a charge.  Guess what?  YOU CAN FIX THAT BATTERY IN ABOUT 5 MINUTES!

107 Comments

  1. Karen McDaniel says:

    Do you think this would work on a cordless vacuum? I have one that I loved but the battery will not charge. It’s not even a year old.

    I’m showing this to my husband who has multiple cordless tools.

    • Karen says:

      It will work with any lithium ion battery but you’ll could have different voltages. Most cordless tools are now around 18V. If the vacuum battery is lower than that it would just take less boosting to get it to be recognized by the charger. Good luck and let me know how it works for you. ~ karen!

      • mike mac says:

        always always always remove any jewelry when working with electronics or electricity. we are made of water, we are naturally conductive, we burn easly, lithium batteries are highly flammable. a little flat birthday card can set a garbage truck or a dump afire. respect the force.

        • Karen says:

          Consider the force respected. ~ karen!

        • Paul says:

          That is really silly. A 18 v battery poses almost no danger at all. We aren’t made of water. We have a pretty high resistance so it is difficult to get a meaningful shock below 50v. You could short the battery through a ring, but the worst you would get is a small hot spot.

      • Roger Lahti says:

        Just came across this tip. Pardon me if I’m applying too much reason to the issue but why are you tearing the battery cover off to get to a positive and negative connection when you already have ones accessible? The two exterior contacts of either side of the plugin arm are positive and negative. You only need to establish which is which. I will try the tapping trick to a dead lithium Robin battery I have to see if it works but this trick will work to get a Nicadbattery taking a charge again, and no need to tear it apart. Use a battery charger at the 2 amp setting or just put the battery into its normal charger and tap plug the charger into an outlet quickly several times, the proceed to recharge.

        • Karen says:

          Because you wouldn’t be charging the cells prior to it going through the circuit board. You need to charge the beginning of the process (the cells), not the end (the stem). For one thing, it’s between the cells and the stem that the problem is occurring, which is why when you try to charge it in its regular charger (through the stem) it doesn’t work.
          ~ karen!

    • liza says:

      I have been on the fence about buying a cordless vacuum for this very reason. If Karen’s ‘hack’ works on a cordless, this will change my life!

  2. Caryl says:

    OMG this is tantamount to open heart surgery! I almost cried but then I had to stop and ask myself “How the hell did she stumble on this????? You’re crazy and we love you.

    • Karen says:

      No stumbling. Dedicated research after being INFURIATED with Ryobi batteries. After having my 5th Ryobi battery die in a year (1 old and 2 BRAND new batteries died within 2 weeks so the company sent me two more which promptly also died … ) I decided these batteries couldn’t possibly all really be dead. It just wasn’t mathematically probable. So I did a bit of research, tried a few things and BAM. A reliable method for fixing them. I’m SO glad I’m not the only one who finds this life changing, lol. ~ karen!

      • JD says:

        First, I loved this article…. A great plan for extending the life of expensive batteries!

        Second… Maybe it’s time so switch to DeWalt. I have batteries that are 10 years old and more that are still charging just great

        Subscribing and Saving, Thanks!

    • Tew says:

      Caryl, you are right. About everything. Well said….

    • Gee Willikers says:

      I haven’t had trouble with my Ryobi yet, but jow Im prepared. Thanks

  3. Gayle M says:

    Clear! (zap)

    Fun article. Thanks again, Karen.

  4. Suel Anglin says:

    This is great! I’m having a near-religious experience. To wit, this came into my mind:

    Hallelujah! Thine the glory.
    Hallelujah! Amen.
    Hallelujah! Thine the glory.
    Revive us again.

    I love Canada and all the people who live there.

  5. Garnet says:

    Excellent! Another of your brilliant ‘stuff’ I can steal.
    Now all I need is a 21st century cordless… anything.
    Meanwhile, I’ll have my publicist call your publicist.

  6. Maria says:

    Fascinating! Cool! Brilliant! Thanks! No vid :'(. I wanna see the vid 🙂

    • Karen says:

      Hi Maria! There is indeed a video. 🙂 Try using a different browser. I’m using Chrome at the moment and it’s showing up perfectly. ~ karen!

      • DGr says:

        Hi Karen,
        So am I and it isn’t. Sorry.

        • Karen says:

          You probably have an ad blocker running on your computer. It will stop things like videos. You can adjust your settings to allow this site to show ads. And any other blogs that you glean information from and wish to help keep them in business. ~ karen!

        • David Grundy says:

          Thanks Karen, it worked a treat, I really like your style.
          DGr.

        • Karen says:

          Perfect! 🙂 ~ karen

  7. Bobbie says:

    Karen, one of the last lines in your post says “Here’s a 3 minute tutorial video showing me as I fix my own battery.” I didn’t see a link to your 3-minute tutorial on your post. Any chance you can add a link to the tutorial to your post OR respond to me a link to your tutorial? I’d love to share it with my husband. I sure wish I’d seen this a couple of month ago before I gave up and tossed two battery powered vacuum cleaners that would no longer take a charge. Sadness.

    I’m an occasional reader, and I LOVE your blog. Keep the hacks, DIYs and the humor coming.

    • Karen says:

      Ack. Bad timing. The video should be there Bobbie. Try using a different browser. Safari is a notorously outdated browser if that’s what you’re using and often things don’t show up with it. Try Chrome or Firefox and let me know. ~ karen!

    • Mark says:

      Didn’t see the video either. Using chrome.

      • Karen says:

        Very strange. I’ve logged out and am viewing t he video like a “regular” reader and it’s there. I’ll look into it in the morning but as of now it’s a conundrum. ~ karen!

        • TucsonPatty says:

          I saw the awesome video and use Safari! I think the gremlins in the technology get bored and do stuff – not like Karen does stuff, but they do bad stuff and that is why the stupid techno gadgets do not work at times!! I am a professional and I know these things. Ha! Thanks for the video and instructions, Karen.

        • ecoteri says:

          nope, no video. on Chrome. nada. nothing. Excuse me while I go buy a multimeter. Always wanted an excuse to do so.

  8. Mark says:

    Your publicist is going to want more money now after being inundated with all the calls… 🙂

  9. Martha Doane says:

    My husband Jim(of exploding battery fame) wants to remind you all to wear safety glasses! Want to guess why?? 🙂

  10. kddomingue says:

    Well, I’ll be damned. And here I was just about to go and buy two new batteries. Question. I have some older Ryobi batteries that will say that they’re charged but will give out after half a screw. And as we all know, half a screw is worthless. (tongue planted firmly in cheek!) Think this method will work on them?

    • Jenny W says:

      Well THAT made me Laugh! 😀

    • Karen says:

      It could be those batteries are genuinely at the end of their life. :/ You can try but I’m not sure it’ll fix those. ~ karen!

    • Bruce says:

      Try giving them the ‘cold shoulder’ – put them in the deep freeze for a day or so, then leave them out to return to room temperature. It works with NiCad batteries, sometimes NiMh and such. Basically the battery can short out internally (NiCads grow metal fibers internally sometimes) and freezing/thawing the battery can make internals shrink & expand enough to break the short. If that fails, you can relatively easily replace the internal cells if you are a good with a soldering iron – the originals will be welded together at the factory with an ultrasonic welder.

      Sadly, some brands are now setting a controller chip so that if the battery pack fails it will permanently kill the battery pack, replacing or ‘jump charging’ the cell/s won’t help.

  11. Sue says:

    Seriously, marriage is not really an option for us, but I just this evening decided that I had probably charged the battery for my drill for the last time. And, I was cursing at the thought of spending big bucks for a replacement – which is not enough. I always like to have a backup – so $75 – $100. Definitely have to thank you for this tip and add it to my Pinterest DIY.
    But, did you say something about changing the battery of your iPad? Was this a post that I missed? Could you share?
    Thank you! Sorry about the whole marriage thing . . .

    • Karen says:

      I changed the battery in my Macbook Pro. I linked to it in the post. I’ve never changed an iPad battery. ~ karen!

  12. Maria says:

    This is a reply to my original post, and a thank you to Karen for your response to my original post :).

    Firefox, no link to vid.
    Chrome. It took a while for the vid to even populate on the page (big blank space like on FF). BUT it did load!

    GREAT VID!

    Karen, now you have a bunch of batteries so there is no excuse of putting something off because you ran out of juice!

    Thank you. (Looking on how to contact your publicist )

  13. PMMK says:

    O. M. G. This is such a game changer. I’m dizzy, I’m so excited! I always knew there HAD to be a way to get those suckers to work again. After all, they are called rechargeable, not disposable. I can’t wait to spring this one on my super smart physicist husband who just grumbles and sulks every time he can’t fix something – like a nearly new battery that won’t charge. I may even show him how to do it.

    I do have 2 questions.
    1 – Is there a minimum voltage that the AC adaptor should have.
    2- Does this method only work on lithium ion batteries or will it work on other older types without blowing them up? We may have some vintage stuff that could be revived.

    You are officially the smartest woman I know.

    I love you and he’s gonna love you too. No proposals though. One spouse is enough.

    • Karen says:

      I *believe* any AC adaptor would work. The lower the voltage the longer it may take to boost. The one I used was 15 volts but I’m sure it would work with a 5 volt one as well … it would just take longer to work up the charge. As far as using this method on something other than lithium ion batteries, I don’t know, so I can’t recommend you do it. Hope you still love me. ~ karen!

      • Stu says:

        I think that if you use a 5 volt adapter, it’ll only charge the battery pack up to 5 volts, and won’t be able to go higher. It worked for you because your adapter was 15 volts.

      • Der Karhu says:

        As Stu said…Karen: hoping that this is not too long a ” saga” for you, or your readers 😉

        A cell phone charger will most likely NOT work, since they are, more typically, 5 to 6 V, BUT, a LAPTOP charger should work, or any charger rated at 12 V (probably would show 14-16 V on your multimeter) A laptop charger is about 19 V, since the laptop uses about the same voltage battery pack as your 18/20 V Ryobi/Bosch/Makita… you can see that there are 5 Lithium Ion _cells_ in your surgically-dissected battery pack.

        Fully-charged Lithium Ion _cells_ are 4.2 V, immediately after charging, but drop to about 3.7 V under load, for most of the battery pack “run time”. Normally, the battery pack protection circuits will shut off the battery at about 2.7 V to 3 V per cell (13.5 – 15 V for your 18/20 V pack of 5 cells), and allow charging, BUT, when the cells discharge to about 2.3 V each, the battery control system will shut them off, internally, to avoid further discharge from totally “killing” the cells; at that point, the tiny voltage that you see on your multimeter is from the tiny amount of “leakage current” getting through the “kill switch” circuit.

        Your method of pulsing the pack to get it back to work is, usually, a good one, and can also be used with some cell phones that appear to be dead, by connecting/disconnecting the charger every 10-30 seconds for a few minutes, this will “trick” the “kill switch” circuit into allowing a small current pulse into the battery pack, and it only takes a small bit of charge to get the cell voltage back above 2.3 V/cell (11.5 V for that 5-cell battery pack), which will allow the battery pack protection circuit to let charging begin.

        For a 12 V battery pack, which has 3 cells, the voltages will be more like:
        – “kill switch” at about 6.9 V
        – fully-charged about 12.6 V
        – normal voltage at end of run-time 8.1 V -9 V
        – In this case, any AC adapter with a rated voltage about 6 VDC should provide about 8 V with no load, which should be “good to go” to re-energize a 12 V battery pack.

        As usual, Karen, great work helping your readers to save some money, save some headaches, and, perhaps, feel the accomplishment of successfully applying “battery CPR” !

        Hopefully, adding a bit of information to the “mix”

  14. Tanya says:

    Karen, YOU ARE BRILLIANT! I’m happily married (38 yrs. ) so I will continue to love & adore you from afar.
    Suel, Exactly! Full choir too…
    KDDOMINQUE, you are funny.

  15. maggieb says:

    Will have to drain a battery on purpose just to have the fun of trying this out!!!

  16. Caroline says:

    OMG! I actually have a Ryobi drill battery that is dead and was going out to get a new one. I’m going to give this a try today and then, if it works, a marriage proposal is definitely on the cards 🤣

  17. Annie says:

    Thanks Karen, I’m trying this for sure. My husband has thrown out lots of those “dead” batteries over the years. I can’t wait to show him this!

  18. Mike says:

    Love the Santa Claus scissors!

    • Lara says:

      Me too, Mike! And I also noticed Karen’s black fingernails, that were in the first few photos “natural” and then suddenly became blackened, only to go back to being au natural at the end of the instructions. What a woman!

      • Karen says:

        Ha! I fixed two batteries. One for photos and one for the video. I painted my nails for the video. Then I realized I forget to get a few shots and did a reshoot on some of the photos. Hence the “mixed” nails. Good eye! ~ karen!

  19. Rob says:

    This is great, thanks for sharing! Is there a reason you have to take the battery cover off vs just pulsing the charger leads to the battery contacts the way the charger does?

    • Karen says:

      You have to charge the batteries at the source – the batteries, *before* it goes through the circuit board to the stem. My guess is doing otherwise could explode the circuit board. ~ karen!

    • Karen says:

      (but that’s just a guess) Either way, don’t try to charge it from the stem. ~ karen!

  20. Ei Con says:

    This. Is. Great. Question though. On this charger cord you’ve mutilated, how do you know which of the stripped wires is the ‘positive’ one? If you accidentally use the wrong wire will stuff blow up?

    • Ross Heitkamp says:

      Use the multimeter to measure the stripped wires, then put black tape on the negative one to remind you. Often one of the wires will have a white stripe on it – usually the positive.

  21. Karin says:

    This is definitely MacGyver worthy! If my husband wasn’t so anal about not over charging our batteries I might get to try this…

  22. Alena says:

    I love my Ryobi to death. It’s not the big “muscle” kind like Karen’s, it’t the lil’ one that has the battery inside (i.e. it’s not removable). (It think it cost $19.99 or $29.99). It’s not the best thing since sliced bread – it is better than sliced bread. I hope it will not die on me; I am always amazed how long it holds charge.
    I put my entire IKEA kitchen together with it.

  23. Lavada says:

    Bloody brilliant!!!!! Thank you.

  24. Tina says:

    You never fail to amuse me!

  25. Kristina says:

    What I’m really wondering here is about that “tutor” treehouse. Is it one where a really smart owl in glasses lives, and people can go there to have him answer questions about stuff? (Forwarding this tutorial to my farmer husband for use in his shop. Very useful indeed.)

  26. Even if you only have a 5v phone adapter, you can do the same thing, but go across the individual battery cell not the whole series of batteries…

  27. Flash says:

    hmmm I will try this. thanks

  28. Audrey Duff says:

    Hi Karen – you’re fantastic – I read almost every one of your posts, and the great comments as well. You have a very entertaining following 😉

    Re the video, when it didn’t work on Chrome, I got it to work on Firefox. Then when I went back into Chrome it showed up.

    I also want to commend you for not having the background music on at the same time you are talking. Very often I stop watching videos because the “background” music drowns out what the person is saying.

    Keep ’em coming!
    Audrey

  29. Micah says:

    Pretty dangerous to try this. There is a high likelihood of fire or explosion depending on the state of the battery. What is described here is a very specific situation, and thinking this will work in general is msiplaced.

    As an engineer developing battery packs, I urge you not to attempt this. These can explode into flame, and burn you or your home. All those electronics you’re bypassing are there for a very good reason.

    • Blaine says:

      ^This guys right!

    • Karen says:

      Hi Micah! I appreciate your comment. It will serve as a warning to those who choose to not follow the very specific instructions I have included for this very specific situation. ~ karen!

    • Lohi Karhu says:

      With the method shown, and following comments that I made, it’s pretty safe…main thing is to limit the amount of current that could be delivered to the battery pack, and a small “wall wart” is not about to blow up an 18650.

      But, one MUST avoid short-circuiting the “open” battery pack!

      • Micah says:

        No, it’s not safe. A wall wart can easily charge a 18650 cell to above 4.2 volts which at best will just shorten the life of the cell, worst case you have a fire on your hands.

        Keep in mind the cells get more dangerous as you charge them. It’s not about current, even a 1 amp charger can blow up a battery. If the charger that’s designed for the pack isn’t working, there’s probably a reason for it. Just jump starting it isn’t a good idea.

        • Lohi Karhu says:

          Micah, I agree that directly applying an uncontrolled charge voltage to a Li-ion cell can be disastrous, and that charging above 4.2 V per cell is definitely bad, probably dangerous, BUT, the whole idea, as shown here, does not involve continuous application of the charge, it does not bypass the thermal protection, it does not connect directly to the cells, and the wires are definitely not “designed” to connect continuously to the contacts…moreover, Karen specifically suggested short pulses, and continuous monitoring of the pack voltage, and only providing enough voltage level to “turn off” the UVLO circuitry…if one ignores every part of this process, and connects directly to the points shown, this is still at a point where the primary safety mechanisms of the pack are functional. With the additional voltage point information that I provided for the pack UVLO (hopefully these numbers meet with your approval?) circuitry to properly activated/deactivated, there is a vanishingly-small danger of any significant adverse event occurring.

        • Lohi Karhu says:

          Micah, when all is said and done, a statement like this:
          “There is a high likelihood of fire or explosion depending ”
          is just plain wrong, misleading, sensationalist…
          I really don’t know how much experience you have at this technology, but this level of rhetoric is well beyond what is appropriate… maybe, something like:”not following the recommended procedure, or connecting voltages to points other than suggested, can result in damage to the battery pack, and danger of the battery pack catching fire”

  30. Blaine says:

    This is kinda sketchy… Charging damaged (which can happen if voltage is too low internally) or unevenly charged lithium cells can cause them to heat up and burst and then spew out flaming melted plastic and violent torch like flames. Charging voltage is also important as putting 18-20 volts from some random wall adapter into a single 1.3v cell could lead to the same disaster. Not all AC Adapters are created equal, some are AC output, be sure to read the printed data on the charger. A little more reading into lithium cells might be a good idea to better understand what state your cells are at before attempting to try this.

  31. Carrie says:

    Thanks for this Karen – I love how you make these intimidating jobs look so manageable! One thing though- I tried to order the screwdriver kit you mentioned (one for my husband and 3 for gifts) but it links to amazon.com and I’m in Canada. Could you please link something similar from Amazon.ca? Thank you 🙂

  32. Renee Ryz says:

    Darn, wish I had seen this a month ago. I took the battery for my Swiffer vac in to a battery place where they will rebuild them – much cheaper – the guy put the leads on wrong, so when I plugged it in, blam blew up the circuit board, and out went a vac that was only a year old. I got a refund for the battery from them, but a new vac is $50 – I bet this would have worked. Whelp, I guess I will be using the ol broom again. I will show this to hubby though – he uses DeWault drills for work, but still good info!

  33. B says:

    I need the inverse- my multimeter was dead even with a new battery 🙁

  34. Richard Dickenson says:

    That’s genius you are remarkable thanks for the great information.

  35. wes womble says:

    Thanks Karen; It made it even moor clear as I viewed you video. Great job

  36. Sandy Howell says:

    Those are 18650 batteries! I use them in just about everything these days. LED flashlights, Vape boxes, Makita chainsaw, Honda RoBo Lawnmower, every laptop I have ever owned, and all my USB chargers.
    Wow, I wonder how I can revitalize my batteries used in everything else (yes, I have a Ryobi cordless). I usually just buy new batteries and authentic 18650s are expensive. I prefer the higher mAh, the highest I have found is Panasonic 18650B, which are 3400 mAh high drain. Anything higher than 4000 is likely a fake- and there are lots of 18650 fakes out there, about 99%.

    The Ryobi appears to have Samsung 2250 with that shade of green casing. Those are a standard in many electronics.

    So what do you think? How can we recharge these batteries NOT in a battery holder?

  37. dav c says:

    How strong does the AC adapter need to be? I have a 5V one.
    Thanks

  38. Audrey says:

    I found you when I needed to change the motor brushes in my washing machine. I’ve stuck with you because you’re helpful and cheer me up. I’ve now fallen in love with you because of this post. Be still my heart.

  39. Jeremie jaymes says:

    You my friend are a genius !! Keep up the great wrk

  40. Don says:

    In an effort to correct some erroneous numbers, each 18650 cell is not 1.3V, but more like 3.7V. Five cells in series (end to end) produces a roughly 18.5V battery pack, when fully charged. With the short-period contact with the output of a 15V wall charger, it is not likely that you will cause any damage to the battery pack. The charging can also be done with a 5V charger just by intermittently connecting the appropriate leads to the + and – end of each cell (the green tubes in the battery pack that look like small “C” size flashlight batteries). Be careful though, because you CAN overcharge each cell with a 5 volt charger. Check the cell voltage frequently, and make sure it doesn’t go over 2.6 volts. If you have any doubt with this way of charging them, DON’T DO IT! It could be dangerous. Go out and look for a 15V charger instead. It should only cost a dollar or two at a thrift store.

    Although it is wise to check the charger to make sure the output is DC and not AC, there aren’t many that output AC anymore. Look at the label on the charger – it will say something similar to “Input – 100 – 240V” with a squiggly line after it (which denotes AC voltage), and maybe” .2 Amps”, followed by “Output 5V” with a straight line with 3 dots underneath (denotes DC voltage), and maybe 1.2 Amps. The “Amps” numbers can be different from source to source, and indicates the amount of power the device uses and puts out. If it has the squiggly line (AC) after the output voltage, don’t use it to try to charge the batteries.

  41. Cliff MCKAY says:

    thanks I will try this.

  42. Bob Funk says:

    If you can see and positively identify the + and – terminals on the battery, and access them, is there any reason you cannot just pulse charge them through the terminals?

    • Karen says:

      Hi Bob, if the problem with the charger not recognizing the battery is happening on the level of the board (in between the cells and the stem) then charging from the stem won’t fix the problem. And in most cases the problem is in the board. ~ karen!

      • TomT says:

        So after the pulse fix. Would we have to open the battery to redo this everytime it need to be recharge?

        • Karen says:

          No, no. The pulse fix kick starts the batter back into action. You just need to do it once. (unless you leave the battery in the charger too long again, lol) ~ karen!

  43. Bob Funk says:

    Does not seem to work on a WORX power tool 20v battery…unless I am doing something wrong. Has anyone had experience with this? Also, is it possible to hook these type batteries up to a Battery Tender Trickle Charger and have them be “pulsed” back to being able to charge?

    • Karen says:

      The last thing you can try is to put the battery in the charger and then plug it in and unplug it (the charger) repeatedly. This is in effect pulse charging. The only time the original technique wouldn’t work is if your battery is genuinely dead – a very old battery for example. ~ karen!

  44. Larry says:

    Karen, I’m new to your feed, but have several batteries I’m gonna try to revive at home using this info. I’ve been using Makita and Ryobi 9.6v to 18v power tools and batteries for several decades, and this would have saved me much money/frustration over the years. I’ll let you know how it goes. In the meantime…. I’m pretty certain my wife of 36+ years wouldn’t approve of my serious proposal of marriage to you, and your husband might not, as well, but just rest content that the sentiment is there. I can only imagine the joy of living with a wife who knows this stuff…….

    • Karen says:

      It would seem pretty joyful at first Larry, but the first time I tried to make the bed with you still in it, it’d lose its charm. ~ karen!

  45. Pablo says:

    Cara Karen,
    My name is Pablo and I am very swarthy but I smell okay. I made my battery like you show in the pictures and now is work too well. So thank you for save me one hundred fifty dollars. Your feet make me crazy. Gracias e buenos dias, Senorita.

  46. David says:

    Girl you are the bomb

  47. william williams says:

    I have used the “on/off/on/off” method on several batteries, and for the most part it works. My question is simply why bother taking the battery apart in the first place? There are easy to access + and – terminals without taking it apart. Thanks for the post, btw.

  48. Rudolph says:

    Just to let you know: If above is not working after all, you can buy replacement cells very cheap at the wellknown Chinese website’s which I will not mention but start with ali and end with baba and so on. You need half an hour spare time and a soldering tool and you have a new batterypack (with probably more capacity then before) for less than 10,-

    • Joseph Cutajar says:

      That could be another solution, only if the batteries have good amperage. Besides the voltage the amps for the batteries need to be good and correct as indicated on the cells. Sometimes these are not true at all and you will find out later that the charge won’t last as long as the original ones.

  49. Joseph Cutajar says:

    I use another solution to revive dead rechargable batteries in the case that they are not recognised by the charger due to very low voltage. One could use another battery with a slightly more voltage than that you have, and using the same principle as indicated above – positive to positive and negative to negative and many times it will work. I hope this helped.

  50. John, 2 way guy says:

    The pulse charge will work unless a battery is worn out. Lithium batteries can only take around 500-750 charge cycles on average. The nickel metal batteries were more. The pulse will work on lithium, nickel metal (NiMh) and NiCad. I have a professional charger that does exactly this procedure. My charger was designed for cell phones. The pulse works better on the older types, but I have used it for years for my own tools. I love the simplicity of your solution, I would do the power “pulse” for 2 minutes and not be discouraged until it took over 10-12 minutes. A word on quality: typically more expensive batteries do use better quality batteries inside. For instance, a $15 battery should not work as well as a $50 battery. For Chinese batteries, well, uh, they are not into quality control like the Japanese or Korean companies. “Nuff said!

Leave a Reply

Your email address will not be published. Required fields are marked *

Optionally add an image (JPEG only)

This site uses Akismet to reduce spam. Learn how your comment data is processed.

The Art of Doing Stuff