Posted: 8/24/2026 5:31:05 PM EDT
[Last Edit: -Obsessed-][Edited]
|
Apparently Milwaukee chargers don't balance packs as they charge. That blows my mind. Anyway, over time, especially in high drain situations, packs can become unbalanced and won't charge. So step one is to see if it is a cell issue or simply a balancing issue. So naturally, I will just charge this one bank at a time to test the theory. If not, guess Im buying a battery tab spot welder.  Attached File I have three packs to do this to. You know, since I never use them or anything. 
|
|
Originally Posted By raverill: Has anyone tried replacing the 18650s in there? That will be phase 2 if this doesnt fix it. Often times it does, for quite awhile. Ultimately having a pack without matched cells and without balancing dueling charging you end up with this eventually anyway. |
|
Originally Posted By -Obsessed-: That will be phase 2 if this doesnt fix it. Often times it does, for quite awhile. Ultimately having a pack without matched cells and without balancing dueling charging you end up with this eventually anyway. Please post pics and the process if you replace them all. I am interested |
|
Originally Posted By -Obsessed-: You know, since I never use them or anything. Probably soaked them with whatever cleaner you use to clean your tools Good luck, Im tagging this one. I had 2 of the 9.0s shit the bed, but I just sent them to a rebuilder through work. |
"Makes me realize why there are warning labels on hemorrhoid cream about not using it orally" - Weomi
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
|
Originally Posted By StarCityShooter: Probably soaked them with whatever cleaner you use to clean your tools Good luck, Im tagging this one. I had 2 of the 9.0s shit the bed, but I just sent them to a rebuilder through work. Well I finished the first phase last night around 11pm. Bank 1 and four were unbalanced vs the others, so charged them both to 4.2v. They took the charge just fine. Went slow, 2A across three cells. It now shows four bars vs three. Will cycle it today when I get home from work and see how long it lasts (I will use my M18 leaf blower and measure the time it runs) and will compare it vs known good batteries to see how it holds up. It only ran for a minute before it showed as dead prior to this experiment. |
|
Originally Posted By -Obsessed-: Well I finished the first phase last night around 11pm. Bank 1 and four were unbalanced vs the others, so charged them both to 4.2v. They took the charge just fine. Went slow, 2A across three cells. It now shows four bars vs three. Will cycle it today when I get home from work and see how long it lasts (I will use my M18 leaf blower and measure the time it runs) and will compare it vs known good batteries to see how it holds up. It only ran for a minute before it showed as dead prior to this experiment. Nice. The blower is a rough one on batteries. Do you have another item to be easier on the cells at first or youre just going for the straight "let er rip" and see if theyre fixed? |
"Makes me realize why there are warning labels on hemorrhoid cream about not using it orally" - Weomi
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
|
Originally Posted By StarCityShooter: Nice. The blower is a rough one on batteries. Do you have another item to be easier on the cells at first or youre just going for the straight "let er rip" and see if theyre fixed? Originally Posted By StarCityShooter: Nice. The blower is a rough one on batteries. Do you have another item to be easier on the cells at first or youre just going for the straight "let er rip" and see if theyre fixed? Originally Posted By StarCityShooter: Nice. The blower is a rough one on batteries. Do you have another item to be easier on the cells at first or youre just going for the straight "let er rip" and see if theyre fixed? I was thinking let er rip and its also easy to measure runtime vs sitting around forever with a grinder or a Rocket light. Ultimately I'm not babying them so figure may as well give it a full send and see what happens. That's usually when these things rear their ugly heads. That and charging on rapid chargers. So if it fails again it could be viable as a low drain pack still but at that point I will find the bad cell and just replace it. Its a pretty straightforward exercise in reality. |
|
I re-balanced an 8 ah milwaukee battery. It didn't take many cycles before it was out of balance again. Some are just made with bad cells - my battery has at least 2 bad cells. I looked at buying a spot welder and rebuilding the thing - but I think the welder needs to be able to weld 0.3mm nickle strips and very few of the welders out there can do it. For 1 8 ah battery pack the welder would cost about as much as just buying a new battery. I looked at sending it off to just have all the cells replaced which was reasonable if I remember - but an 8ah cell is over the hazard level the shippers will accept without special handling fees. Which made the cost not worthwile. |
|
Four cycles and it is still fully charging. Blower ran 18+minutes on low. Seems about right for 9.0Ah? Have been running a box fan off it today. Attached File |
|
Originally Posted By -Obsessed-: Four cycles and it is still fully charging. Blower ran 18+minutes on low. Seems about right for 9.0Ah? Have been running a box fan off it today. https://www.ar15.com/media/mediaFiles/467079/17162_jpg-3819129.JPG Looks more like you've been running a pressure washer off it to clean your tools Seriously though, nice work getting that battery fixed  It sucks being so vested in their system and knowing theyve got a few highly known lemons in the battery line that dont alway make warrantee time. And theyre not fucking cheap 
|
"Makes me realize why there are warning labels on hemorrhoid cream about not using it orally" - Weomi
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
Save VA, Join or Donate to VCDL!
https://www.vcdl.org/Donate
I have the 8Ah HO battery finished as well. I'm not as confident in that one getting fixed. The 8AH has a 5S2P 21700 cell layout, and even with that layout the resistance of one of the banks was very high...157mΩ  . It also had 3 bad banks out of five. the really high resistance bank was only 3.5V, the two good were 4.2, and the other two were 3.7 and 3.8.I may have to disassemble it and see exactly what cells are used. I may even just totally rebuild the pack with better cells. It blows my mind, truly, that NONE of the major manufacturers balance battery packs as they charge them. Not a single one. I'll give credit to DeWalt though...they at least pin it out. So in theory, you can balance charge a DeWalt battery on an RC charger if you want. Honestly I'm tempted to shift to DeWalt for that reason. But maybe I'm being rash. I have 34 tools now from Milwaukee so it would suck bigly to change now. I may, alternatively, design and print/build a balance charging jig. It wouldn't be too hard to set up a jig that I simply sit the battery inside and it makes the necessary connections via springs/lever arms. I could just proactively discharge and balance charge each of them once a year, but it would require proactive disassembly. |