Amazon 48v battery inspection

they have 35e wrappers
first issue i see is the solder iron burnt the cell holders


the rest looks fine except that the shrink wrap is getting holes rubbed in it, ill be hanging this battery upside down so ill just silicon the upper case shell to the pack and it wont rub anymore



going to charge it up and do a capacity test on it
after first charge it settled at about 53.6v and i plugged the charger back in to try and balance it a little more.
second charge it settled at 54.2v after about 16 hours off the charger
hooked up the load tester but im limited to 185 watts so just put it at 3 amps and wait til the bms shuts it down in 5 or 6 hours
edit. i just looked and the bms shuts down at 36.4 volts or 2.8v/cell

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Return it, that cell with the burnt wrapper is probably damaged by the heat, wow
the proper solution would have been to spot weld a tin strip to the cell and then solder the wire to it.

Kudos to you for opening it up.
theres proper yes but im one of those guys that would solder entire battery packs. the capacity is where it should be so im not worried about a negative tab coming undone at the negative side.
my Begode Master is 32s4p of 50E cells. 4-8s4p packs connected in series where i soldered copper foil to the pos/neg of each pack about 14,000 kms ago and about 300 charge cycles

not sure if youtube works here but heres what i mean about soldering entire packs

edit *** battery has been off the charger for about 3 hrs and is sitting at 54.6v***

thats about it, if something goes wrong ill post about it
but im not worried about this pack from what i see
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they have 35e wrappers
Well, they are pink and say 18650, but do they say Samsung 35e ?
View attachment 351283
first issue i see is the solder iron burnt the cell holders
That wrapper burn through to can metal edge might be of concern if it were on the cells' positive end instead of its negative end (which is no problem).

5p times 8amp MCD = 40 amp MCD rate. Do you know if the BMS MCD rate is 30, 35 or 40 amp? My guess is it's more likely a 30amp than 40amp BMS in order to prolong battery cycle life ALAP.

"Equipped with BMS protection board to prevent overcharge, overdischarge, overcurrent, and short circuit to ensure long life." This BMS language for your 13s5p as found on other such comparable batteries is usually understood as having no balancing feature. Which some would contend isn't needed when using A-grade name brand cells of consistent 1st rate quality.

What say you?
cell holders block the 35e part of the wrapper and it does say samsung like in this pic but a wrapper isnt hard to counterfeit but they do look like this
what say i about the cell balancing. it has cell balancing or it would not have balanced and as cells age their at rest voltage will drop from 4.2 to 4.18 to 4.15 to 4.1 just because of capacity loss and if youre charging to 4.2 when the cells can only hold 4.17 and some 4.16 and some 4.12 youre not balancing youre throwing them out of balance.
what you really need is a bms that can be programmed to balance at 4.1v afaic so youre not overcharging cells at 4.2v as they age and just making the damage worse

like you said the burn is on the neg and it didnt burn a hole in the wrapper

i think it said it had 40amp discharge on the bms
on this pack is going on a 20 amp bike

i was just fiberglassing the pack holder to mount it upside down and sika flexxed the pack to the shell inside, itll be finished tomorrow, got some grinding and paint yet to do. pack voltage is 54.4 right now