ucw458 Posted March 9, 2010 Report Share Posted March 9, 2010 Like alot of you I have NiCad and NiMh batteries that refuse to charge. I have 9 battery packs for my cordless tools and only 2 of them work good. I really didn't want to go to Home Depot and buy more batteries. They never last long anyway so I lookeded into ebay for upgraded cells to put in my batteries. I stumbled across a battery trick that actually worked. Take your cordless tool batteries apart. Then use a 12v car battery and connect each cell to the battery for just 2 seconds. 2 seconds is all you need. My 18v ryobi batteries have 15 cells so 15 "jumpstarts" per pack. Then re-assemble the pack and immediatly stick it in the charger. Now your battery that wouldn't charge or would only partially charge and die almost immediately will now work like new. This saved me alot of $. Now instead of spending $60 to get 2 new batteries and only having 4 good batteries, I spent zero $ and have 9 good batteries. WOOT Don't try this on litium batteries. All the batt trick videos warned that lithium batteries will explode if you try this. Link to comment Share on other sites More sharing options...
jahjah Posted March 9, 2010 Report Share Posted March 9, 2010 hmmm... i wonder how this works. does the amperage of the car battery force the tool battery to see its full life usage(or whatever you wanna call it) so that it will accept a full charge again? i thought the failure of the tool batteries had to do with the degradation of the acids or whatever inside the cells, i don't see how a car battery could bring life back to the chemicals int he battery... of course i could be completely wrong on this lol Link to comment Share on other sites More sharing options...
ucw458 Posted March 9, 2010 Author Report Share Posted March 9, 2010 So far I've done this to 5 of my dead batteries and it worked on every one. I only have 1 charger here atm so it's a slow process. You need a stable 12v DC power sorce. Since everyone has a car battery that's the easiest sorce for current. Plus the amperage available helps the process. Over time it seems NiCad and NiMh batteries can get confused and reverse polarity. Weird but it happens. When it does, 1 cell can stop the whole pack from charging. By "jumpstarting" with a car battery is conditions and resets the polarity of the individual cells. Basically restoring an old dead battery pack to "like new" condition. All my work tools are cordless because I work on constructions sites with little to no power. Having all my batteries back and working properly is great. Especially since it didn't cost me any $. One of my batteries was around 7 years old and came right back to life after doing this. Link to comment Share on other sites More sharing options...
JAinsworth Posted March 10, 2010 Report Share Posted March 10, 2010 I had a cell phone that wouldn't charge, took it to the service provider and they "shocked" the battery. It worked fine after that.Jimmy Link to comment Share on other sites More sharing options...
TheWormForEver Posted March 10, 2010 Report Share Posted March 10, 2010 Yea I talked with my dad on the phone about this post. He's an electrical engineer, and told me that this can actually work. He asked me if I was doing it, and I told him no. Apparently, this should be done with a circuit, and an electrochemist should gauge how much current should be put into the circuit. I guess the battery packs can burst or explode easily and take off a finger or spray you with acid. At least that's what he told me when i asked him about it. Link to comment Share on other sites More sharing options...
mikec Posted March 10, 2010 Report Share Posted March 10, 2010 This explanation applies to NiCad batteries - they're the ones that can be recovered by the zap technique. The original failure/problem is "reverse charging" of one or more cells in a battery pack. Battery packs as we all know have multiple individual cells. For NiCad packs, each cell contributes around 1.2 volts when charged. Ideally each cell has exactly the same voltage and charge capacity as its companions but that is never the case - all batteries are slightly different. Now, as you use the power tool, radio, portable computer, whatever, each cell contributes 1.2 volts. The device draws some amount of current (i.e. amps) which flows from the battery cells - each flows this same current. As the cells discharge, their voltage drops a little bit. Eventually the weakest battery cell reaches its capacity limit and its output voltage plummets to nearly zero. Keep using the tool... and that cell totally discharges. Keep using the tool and the current flowing from the remaining cells also passes through that discharged cell. This current starts charging the cell BACKWARDS - i.e. reverse charging it. This reverse-charge causes small metal whiskers to form from the internal cell parts (due to the chemical reactions inside the cell catalyzed by reverse polarity charging). These whiskers grow from one polarity end of the cell to the other - until the + and - metal parts inside the cell actually get connected (shorted out) by whiskers. Once this happens, the battery is shorted out... if you try to charge it, nothing happens. Connecting that cell to a car battery, or some other power source that can supply a LOT of amperage, melts those whiskers into oblivion just like blowing a fuse. Then the cell is usable again. It'll have nearly all of its capacity prior to the whisker formation; some capacity is lost because part of the internal cell is literally melted/gone now. Still, 99% is better than 0%. Once the whisker short-circuit blows, the cell begins charging from your car battery or whatever... you're hitting a 1.2volt cell with 12 volts... from a 12volt source that has lots of amperage capacity (think a wide river compared to a drinking straw of water). That 12volts pushes too many amps into the NiCad cell trying to charge the cell... leading to a LOT of chemical heat. Leading to "boom" if you leave things connected too long. Using a higher voltage source to "zap" the cell is even more risky. Don't try using a wall outlet! Other battery cell types (nickel-metal hydride, lithium ion, etc) don't exhibit this "whisker growing" phenomenon which is why, when they won't hold/take a charge, doing the "car battery zap" trick is not the correct fix. It's just a good way to make a real mess. The key to keeping NiCad cells from whiskering is to quit using the tool/computer/whatever when the first cells start plummeting below 1.2 volts. When the drill/whatever suddenly slows down, STOP. Any more leads to shorted out cells. mike c. Link to comment Share on other sites More sharing options...
ucw458 Posted March 10, 2010 Author Report Share Posted March 10, 2010 If you do it for a short time like 2 seconds you wont have to worry about the battery exploding. I just did it to 6 packs, that's 90 cells I shocked with no incident. And I still have another 81 cells worth of battery packs to revive. Link to comment Share on other sites More sharing options...
quikconq Posted March 10, 2010 Report Share Posted March 10, 2010 thank you for posting this i never heard of this,,,and i have 3 dead dewalt 18 volt batts ,,and two others that are getting ready to die,,,sounds like ill be taking some batteries apart.... thanx again its always nice to save monies latersbryen Link to comment Share on other sites More sharing options...
nomad Posted March 10, 2010 Report Share Posted March 10, 2010 If you do it for a short time like 2 seconds you wont have to worry about the battery exploding. I just did it to 6 packs, that's 90 cells I shocked with no incident. And I still have another 81 cells worth of battery packs to revive. Do you need to seperate the individual cells from the other cells, or can you just work around the tabs that connect cell to cell? Link to comment Share on other sites More sharing options...
ucw458 Posted March 10, 2010 Author Report Share Posted March 10, 2010 Do you need to seperate the individual cells from the other cells, or can you just work around the tabs that connect cell to cell? You don't have to take the cells apart. You do have to remove the plastic case so you can zap each cell 1 by one. Leave the cells connected to each other. It takes about 5-10 minutes per pack. Link to comment Share on other sites More sharing options...
Komeuppance Posted March 10, 2010 Report Share Posted March 10, 2010 Basically, you Fonz'd it. Zap, Eyyyyyyyyyyyyyyyyyyyyyyy!! I like it. -Robert Link to comment Share on other sites More sharing options...
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