donât put one of those in the wrong way around
Donât worry they are wrapped with heat shrink and the stock ring, all I had on hand just happened to be clear lol
Most of the original wrap got messed up pulling the glue off so easier to just surface the ends flat and rewrap before rewelding
This is why I placed it here and not in parts for sale. Figured a person following this thread would see it.
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There should be a laser-etched code of the can though, about halfway down the side. No idea what the code says or it itâs a serial number.
Thatâs what I would have thought, but they either have a red and blue dot or nothing
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Did my first real discharge down to ~30% and this was the BMS reading, the biggest difference iâve seen yet.
Charged it up and it balanced pretty well
Does it look like the 5th pack would need replacing in the future?
Is that a brand new pack?
The delta isnât bad but iâd be concerned if the pack is relatively new.
pretty much, got only a few charges on it.
Yeah, that is concerning for a new pack with new cells. I would suspect that group 5 is at least several hundred mAh short of the others, which could indicate a bad cell, or a bad cell connection (broken spot welds).
Definitely not an immediate end-of-the-world scenario (as long as you donât discharge it so low that that group goes below 2.5v it shouldnât damage anything or be a fire hazard, for example), but it will only get worse from here on, because the lower capacity means that group will wear at an increased rate, and lose more capacity relative to the others.
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I hardly ever drop below 3.1v on my packs.
i currently only have 3 out of 6 cells on hand to do the swap, and im not spending $60 at the moment just to get the 3 more i need(waiting to make a bigger order).
Could i just add some more spot welds to that p-group or should I just wait to swap out the whole thing entirely?
I get the brand new cells at 3.55v. To get the rest of the 17 packs to match, do i just cut the charging when it gets around that voltage?
If the issue is broken welds that could do it. If one of the cells is bad, then youâd need to replace it.
You could go poking around the bad group with a multimeter and see if any individual cell reads lower than the rest, or if the BMS reading changes while applying pressure to the nickel, and you may be able to find the loose connection (if thatâs what the issue is) that way.
Yeah, it doesnât matter what the voltage is, as long as theyâre all close to each other. You could charge everything to 4.2, or match at 3.55, or anywhere in between.
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This wouldnât work unless the cell in question was completely separated from the rest.
So its likely just 1 cell is bad? would it be worth it to open up the pack right now with the 3 spare cells i have on hand, or wait until i can replace the whole 6p?
Looking at those 2 readings alone my suspicion is you have a bad cell or bad connection, somehow the capacity of that parallel group is a touch lower than the rest, Iâd check all the welds (especially negative side) to see if a cell has been disconnected on one end, otherwise it might mean one cell is defect and has less capacity. It wouldnât be a short since the delta would get worse as you charge
I wanted to charge to 3.55 but ended up charging to 3.644 on the p-group in question. Is this safe for me to put the new 3.55v cells into, or do i have to discharge the 5th group a bit more?
If each individual cell reads fine, then is it just a matter of adding /redoing the welds?
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Youâd have to measure capacity separately which is hard
damn so its not as simple as just probing it with a meter to read the voltage? sounds like im better off just replacing the whole group
So you could disassemble the parallel group, reweld all those cells in series, then drain it into a resistor for a while and one cell might read low, and that would be the bad one
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