Do you guys charge all Li-on cells before you weld them together to a pack?
I have 72 21700 cells and all are at 3,54v, I dont really have to right?
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Itâs best to not build a pack with fully charged cells. Most important is that they are at the same or almost the same voltage
Are those spotwelds good? @Acido
They were done with the bossspotwelder at 2x 5/6ms with 1ms between and 0.2mm nickel to nickel
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You could just check the wiring diagrams of both bms and compare them to be sure whatâs the difference.
The first pin on the d140 isnât used or necessary to wire up as itâs connected on the pcb with B-
Guess thatâs not the case on the D595
Someone on the onewheel facebook group is making and selling these packs, and plenty of people are buying them.
Isnât this a good example of what not to do with the ballance wires?
(âFinished productâ by the way)
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Now, I donât know battery building or anything, but that looks like a fire waiting to happenâŚ
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Yeah thatâs not looking healthy at all⌠Looks like it could be built safer.
I think my perspective is skewed though, My last pack I insulated each P group + terminals and even cells in each P group individually (I know this part is not necessary) with multiple redundant layers of Fish paper + neoprene padding + more fish paper + more kapton + heatshrink + more kapton, etc. It came out much larger than it needed to be but at least it gave me half peace of mind. When I absolutely cannot avoid crossing a balance wire, I put fish paper on the bottom, top, and in between where the balance wires cross and secure with kapton and hot glue.
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Rip it apart. If bits from one strip is not stuck to the other, turn it up a bit until it does.
Itâs hard to tell tbh. The balance wires are all mixed up but if itâs insulated underneath from the battery, is fine. Unless something is going to be pushing down from the top there, nothing will really happen to it everâŚ
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That looks great actually.
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Looks like the last cell shown in this clip held on to itâs heat for a while there. Doing multiple welds back to back heating up the cell above safe limits?
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Yes but that amount of heat is negligible and it dissipates really fast, compared to soldering on cells
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Great video on the matter
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indeed Warmer, given corner position with only one neighbor to accept heat vs middle cell with two neighbors on either side.
But consider the scaling here. Spot welder Wires were waaay hotter. I am way hotter. 
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Hey guys. Quick question: does this seem crazy?
Iâm planning to eventually convert the acid batteries inside the ebike I just bought
Itâs currently running 6x12v 20ah lead.
I believe it should fit according to the 2am math I just did
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if you donât need all the discharge of 30Q could get higher capacity cells like 35E for more range in the same volume
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does the 35e actually weigh 4.4grams more or is that an error?