How to repair a power tool battery that stops charging at 50%

[@taoyen1579]

i honestly thought you were going to jerry rig it to your turnigy charger to balance everything. didn't think you were going to manually do it, thanks for the lessons.

[@vuaeco]

You could theoretically rig it on a Turnigy balance charger since it's a 6S battery. But with such big differences in voltages, even the Turnigy would have a hard time balancing it. This is a lot faster.

[@JohnClulow]

Excellent video! Thank you!! I wonder why this battery became unbalanced in the first place.... and whether it become unbalanced again if the same causes and conditions exist. Maybe a couple cells have higher internal resistance - under load their voltage and current may be lower causing them to discharge at a slower rate thereby elevating their relative voltage when not under load? Check all cell voltages under load to find out.

[@rp42069]

I have the same problem with my kobalt batteries. They won't warranty them out at lowes for me. I'll try this! Thank you

[@doctorlefthandthread]

Great video well described excellent method

[@tims8603]

Good info. When you checked and some were high, I thought, he'll discharge the high ones. I guessed right. I didn't guess that you would charge the lowest one though.

[@chodechotchney5331]

I love this guy

[@topgun52]

How did the batt get out of balance in the first place? Seems like the BMS my have an intermittent fault that will probably fail again.

[@vuaeco]

2 reasons I could think of: 1. Manufacturer quality control. They didn't put the cells of the same voltage together in the first place. 2. Cell quality. Lower quality cells are used and they got self-discharged. Or maybe you're right, it could be intermittent faulty BMS.

[@nayy31]

I'd really love to see you build an inverter with the kobalt 24v batteries. I have quite a few batteries just sitting there doing nothing for most part.

[@nayy31]

I just fixed mine thanks to your video. Has the issue repeated itself since you fixed it?

[@DepthWish]

Nice work, you make these test look super easy. How about a portable razor that barely recharges... have you repaired one of those yet?

[@vuaeco]

Most of those razors use a single 14500 cell which is the same size as a AA. The Brawn razors use a single 18500 cell. Since there's only one cell, there's nothing to balance. If it goes bad, you have to replace it.

[@lancealderman2755]

Doesnt make sense if the balancer is working correctly and the cells arent mismatched (which I believe youve shown by checking discharge voltage and then charge voltage after you manually balanced) how the pack became that unbalanced in the first place. Seems it would have to be from an outside force. Regardless, good video. I believe that most people will find a cell that has lost capacity and both discharges faster than the others, causing the bms to turn the pack off, and also reaches fully charged voltage before the rest, causing the bms to stop charging before it is fully charged. (Then possible repair is to replace the faulty cell)

[@tims8603]

Those BMSs in power tools aren't high quality due to cost and size constraints. Individual cells also have different internal resistance.

[@rochedejager7862]

Great🎉

[@naps3386]

If you open a battery pack and all cells are 0, are they recoverable?

[@rp42069]

I think if at 0, no good. If I remember right.

[@evanbisson159]

do not charge them, you risk fire at that point. all the charge will pass as heat.

[@naps3386]

I took all the cells out and charged them using direct connection to another 18650 battery for 3 minutes and then immediately putting them in a charger. 4/5 batteries charged to 4.1 V, the 5th would not charge. The cells got warm but not hot and charged within a couple hours.

[@billrimmer5596]

What I don’t understand is how the BMS allowed it to get imbalanced in the first place. Why do u even need one if it doesn’t keep the cells balanced? U have a comprehension of that stuff that is way out of my league. I have that very same battery. I have the 24 volt Kobalt impact that I use for really tight bolts. My normal daily user is the Ryobi 1/2 drive when I just need decent power. Electric tools r great. I think your wife doesn’t want u to become a KZbin star. She doesn’t want people coming and bothering u like they would Matt’s off-road recovery guy. But maybe it’s u who doesn’t want the notoriety?? When r u going to quit your real job? Kidding

[@vuaeco]

2 reasons I could think of: 1. Manufacturer quality control. They didn't put the cells of the same voltage together in the first place. 2. Cell quality. Lower quality cells are used and they got self-discharged. Or 3. It could be intermittent faulty BMS. Well, I'm not at the level to quit my day job yet. Still hanging on...paying for one bill at a time, paycheck to paycheck...