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Rebuilding Power Tool Battery Packs with New Cells

Mike attempts

17,687 views

After rebalancing the cells in two old Milwaukee M18 battery packs, one is already down to 3 bars after the first recharge while the other won't hold a charge at all. I figured this would be a good opportunity to compare soldering against spot welding when rebuilding the packs with new Samsung lithium-ion cells. This procedure for replacing the lithium-ion cells in power tool battery packs will work for Dewalt, Makita, or any other brand. See links below for the parts and tools I used:

Spot Welder:
https://amzn.to/4oDG84c (affiliate*)

Flush Cutters:
https://amzn.to/4oENtQO (affiliate*)

Weller Soldering Station:
https://amzn.to/4a0SiAu (affiliate*)

Weller 5 Tip Set:
https://amzn.to/3Kv9EuU (affiliate*)

Bass Sponge Tip Cleaner:
https://amzn.to/3MknL6O (affiliate*)

Liquid Solder Flux:
https://amzn.to/4pSJ6CT (affiliate*)

Lead-Free Solder:
https://amzn.to/4rYagdx (affiliate*)

Aluminum Soldering Clips:
https://amzn.to/48yZtNJ (affiliate*)

Battery Charger:
https://amzn.to/47bQpOl (affiliate*)

Security Bit Set:
https://amzn.to/48wcKIH (affiliate*)

Slim Multi-Bit Screwdriver:
https://amzn.to/42K6c5u (affiliate*)

*Purchasing from these Amazon affiliate links earns my channel a small commission. Think of it as a tip that doesn't cost you anything. Thanks for the support!

19 Comments

@Mikeattempts Creator 9 months ago Pinned

Spot Welder:
https://amzn.to/4oDG84c (affiliate*)

Flush Cutters:
https://amzn.to/4oENtQO (affiliate*)

Weller Soldering Station:
https://amzn.to/4a0SiAu (affiliate*)

Weller 5 Tip Set:
https://amzn.to/3Kv9EuU (affiliate*)

Bass Sponge Tip Cleaner:
https://amzn.to/3MknL6O (affiliate*)

Liquid Solder Flux:
https://amzn.to/4pSJ6CT (affiliate*)

Lead-Free Solder:
https://amzn.to/4rYagdx (affiliate*)

Aluminum Soldering Clips:
https://amzn.to/48yZtNJ (affiliate*)

Battery Charger:
https://amzn.to/47bQpOl (affiliate*)

Security Bit Set:
https://amzn.to/48wcKIH (affiliate*)

Slim Multi-Bit Screwdriver:
https://amzn.to/42K6c5u (affiliate*)

*Purchasing from these Amazon affiliate links earns my channel a small commission. Think of it as a tip that doesn't cost you anything. Thanks for the support!

@SaraLord-p1b 3 weeks ago

Mike what a great video, old school style YT at its best. No glitz and I learned more than expected, thanks again and keep up the good content.

@coburn_karma 9 months ago

Reminds of opening a can of Corn Beef, where you roll open the metal strip. Good Refurb. You got balls of steal.

@nelchan2421 9 months ago

Use a small diamond-coated round ball die grinder bit to remove old nickel from the cells.

@jocelaineoliveira9868 9 months ago

Hi, great videos. The translation is excellent. Today I learned something new, I didn't know about the safety feature. Could you make a video about small screwdrivers? Like the Bosch Go?

@kingrpriddick 1 month ago

You wanted Samsung 25R cells would’ve been much better for this. I in many others don’t like the 30Q because that’s what was in the 9.0 batteries and even with three in parallel (that’s 1/3 of the load) they struggled to stay balanced, and many people saw the middle cells have thermal problems because the 30Q has a higher internal resistance.

It’s simply not really a good high discharge cell.

@DrGreen-wl2ry 3 months ago

Not nitpicking at all, but you should remove your ring when tinkering with electrical. If that sucker shorts out you’ll be dancing around! Good videos though!!

@boots7859 9 months ago

FYI, there are several folks online who will replace bad cordless pack batteries with new cells for less than the cost of new OEM. And they will use better cells than OEM as part of the deal.

@tedz74 9 months ago

Why not use leaded solder? The lower melting point might help with the process.

@ДмитрийЛапа-о3ъ 9 months ago

You can soldering long time 10 sec no problem...

@ErtsenPlayGames 9 months ago

that solder is baaaad , i used 200w big solder , takes half a sec to apply solder on negative side (on entire surface !) and it works rly good

@bgregg55 5 months ago

I've quit buying most rechargeable tools with these lithium battery packs & gone back to plug in alternatives.

@NancyShanteau 6 months ago

Did you do the solder on the second pack or just the spot welding? It seemed so much cleaner!

@kingrpriddick 1 month ago

Max continuous discharge is not respected by anything in the Milwaukee ecosystem, the cell will discharge much more than that it will just die faster. Like you talked about shorting a cell. So picking a cell with a lower discharge rating is doing nothing to protect the circuitry in the BMS.

@JoeBaller1 9 months ago

do you expect both of them to work now for a couple of years or what

@mikko3d 7 months ago

It's better to hold the welding tips on separate sides of the slit in the connecting strip. This way there is more resistance for the current to just pass across the strip and more heat is focused in the weld area, at least in theory.

@BrucePierson 9 months ago

A while back, I repacked our two leaf blower batteries, which you might remember me mentioning in one of your other videos. I bought new cells and I also bought nickel strip on eBay and I used my 80W soldering iron to solder the strips to the cells. I figured a nice hot iron would make a quick job and not risk heating up the cells. I found that the 80W iron did a pretty good job on the soldering, whereas with your lower wattage iron, the soldering wasn't so neat. I have never tried welding the strips to the cells, mainly because I don't have a spot welder and I didn't want to buy one. If I have to repack another battery, I will just use the 80W soldering iron, as it worked OK for me the first time.

@BrucePierson 9 months ago

It was interesting that the new cells you bought were of a higher capacity than the old cells. I found the same thing when I repacked our two leaf blower batteries. It could be advances in technology which result in better mAH capacity for the same sized cell.

@Toryons 9 months ago

I know it's Mike Attempts, and you attempting to place an online order makes for a boring video, but what was the price difference between replacement batteries and new cells? Was it worth it? Or do you think you would just buy new ones in the future?