Dewalt Battery won't charge? Try This!!! 

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One thing that hasn't been brought up is that the strips that you get with the spot welder is 99% chance of being nickel plated steel. Couple of reasons why they include plated steel vs. pure nickel is; Its cheaper for them, it's easy to spot weld than pure nickel. Big drawbacks are; nickel plated steel will corrode and rust over time and it carries less amps, which is important in a high drain device like power tools. For example .15 × 8mm copper 18A of CDR, pure nickel 5A, nickel plated steel 3A. 2 ways to test what you have. I'll take Dremel with cutoff wheel and cut a little of the strip. If you see sparks, plated steel, no sparks, pure nickel as nickel doesn't kick sparks. If u want to be double check, make a salt water solution and put a small piece of strip in. If no corrosion the next AM, pure nickel. Shows heavy corrosion, plated steel...

Great work my friend. I love this kind of content

Well done, great job👌

Few warnings: I would isolate the other cell-ends with tape before removing and adding the nickelplates, it's easy to short the cells. Furthermore, I'd check the cell battery voltages after a few charge cycles to see if they keep their balance. If charging takes much longer you know there's an inbalance in the pack and more cells needs to be replaced (I'd replace them all if the pack is old). Performance will be better if the cells are from the same production batch. PS. I'd work on a desk instead of on the ground, makes it easier to do the job. 😏

That runs...but control the right balance after a few charges and discharges, because you add new cells to old used cells, with certainly different internal resistance.

Thanks for the tutorial. I'm looking to do this myself. How did the battery hold up after the repair? Anything you would do differently?

Thanks so much for your useful video! How many mamp for a single battery? Thanks again!

Always charge or discharge the new or any battery to the same voltage when you rebuild or build your pack.

You're not done yet. If you have a power supply, you can use it to balance charge the cell pairs separately through the Dewalt battery contacts. Set the power supply charging voltage to no more than 4.2 volts. If your cells get above 4.2V, they would catch fire or explode so be careful. You can bridge the power supply and the Dewalt battery contacts using paper clips with the insulation stripped. It's going to charge very slowly taking hours to bring the cell pair voltages up as it is essentially equalizing to the power supply voltage. Cell pair 1 is B- to C1 Cell pair 2 is C1 to C2 Cell pair 3 is C2 to C3 Cell pair 4 is C3 to C4 Cell pair 5 is C4 to B+ Get all the cell pair voltages to be more or less equal to each other. Then battery is balanced. Doesn't make much difference whether you bottom balance, top balance, or any voltage in between. That's for an advanced discussion. Try to get the cell pairs to be within 0.02 volts of each other.

Can you detail the tools used, most specifically the spot welder please

Perhaps an OPUS battery charger/discharger would be good to add to your collection (plus the modded cooler fan). You can great test each cell and roughly gets its mAH reading. You can also get dedicated IR testers. Also I’m surprised that cheap welder did the job. You can make one or go for a decent branded one for £100. The problem these days is sourcing cells. It was easy before EBay and others cracked down on postage due to fire hazard. It’s getting cheaper just to source a whole new unit battery pack now sadly. Good video for an amateur and from now I never bin bad units but keeps/test/label each cell.

how do you check for broken boards? whats the indicator of faulty boards?

I slightly nicked the green wrap on one of the battery’s so covered it with black electrical tape is that ok doing that?

Does anyone know the name of the lil spot welder used in the video?

Got two 5ah batteries from ebay. Seller won't refund or exchange the one that won't charge. I don't think I am up to foolin with tearing it down and have already tried the jumping it from tge other battery trick- no go. Do you know if Dewalt will replace it?. It was new in the packaging when I got it.

Is the solder on the battery itself?

What cells do I need for a 18v 4AH DeWalt. Many thanks

What's that tool u ust to reconnect them

Where did u buy replacement cells from? There are a lot of fakes out there for me

Where can I find that welder

i just bought a rechargeable battery back on the clearance rack 10 dollar with 10 18650 in it .

Place batteries on counter, slide debt card through machine.

Send me a link to buy replacement batteries

I do not see the point of testing and replacing individual cells. If a couple have failed, the rest are probably not far behind. Why not just change them all?

You didn't connect the end cells

You could have likely respot welded the existing nickel plates. Instead of removing and putting new ones

@stownley2005