Then measure from the black wire progressively across the balancing harness. Write down the voltages and post them here. Fyi, you wanna measure from this part of the harness:
This will tell you the voltages of each p-group. Be cautious and move slowly. Clear your work space of anything metal. Use plastic or ceramic tools where possible if needed
Iād like to second this part specifically.
DONāT accidentally short anything out. Wear safety glasses in case you do.
For the sake of completeness, whatās the procedure in this case?
Ex. Testing pins and accidentally short 2 of them, then what would one do?
My guess: Remove, replace and dispose of affected groups?
The most likely in my opinion but definitely not the only outcome of something like that, would be replacing the connector that goes into the BMS. Which are often really long JST connectors that are real hard to find and super-dangerous to assemble with already-energized balance leads.
I doubt it would harm the cells much, as a balance wire or the connector part you touched or whatever you touched it with would likely fuse away first.
Also poop-filled trousers. Unless youāre a rebel and build vehicles without wearing pants. Then the trousers stay clean.
Iāll tell ya what, this is the point where I will handover the battery to my battery guy 
, but thank you very much for the information !
NP. And I hear itā¦ the wise man knows his limitations. Good luck with the pack!
hey guys im building my first batt 12s3p 21700 do u guys have any recommendations for charger and bms?
WATE 50.4V 4A charger
LLT 12s 20A Smart BMS
Hey i i wire a bms in charge only the amp rating does not matter because that is the discharge rate right? im looking at some smart BMS and they all have that ratting 20a all they way to 120amp
Yes. For esk8 you wire the BMS in charge only with direct discharge. This means discharge current is only limited by the cell spec and the charge current is limited by the BMS.
For other applications like ebikes and escooters you use higher current BMS and discharge through the BMS as you donāt need a direct reliable connection to facilitate brakes.
thanks dude! i really didnt wana spend 120$ to match my ESC amps!
How would the bms being used for dischage protect anything? what kind of failure could happen where the bms would protect when overseeing discharge?
I imagine if the esc broke without the bms overseeing discharge then huge current could go to the esc, but itās already broken, so Iām guessing the bad scenario is if the esc broke resulting in a CONTINUOUS SHORT then the battery would be at risk but do escs break resulting in a continuous short to the battery?
I imagine the batteryās ability to put out current and blow away a possible continuous short in the esc maybe decides and having a powerful battery could be the safest choice if thereās a risk of continuous shorting to esc.
alot of ebike batteries are also bypassing bms for discharge
Is this just so they can get away with a lower current BMS or are they doing it for the same reasons as us?
not exactly sure but some companies that use a BMS for discharge claim itās due to cost savings
i think theres a power button the bms has that is used to turn the unit back on after it shuts itself off? not sure just guessing its less to deal with having it bypassed.
All BMS Iāve seen with a. Switch feature have a way to not use the switch and have constant discharge.
Donāt e-bikes just end up coasting to a stop when the BMS cuts off power? A much smaller jerking of the rider vs esk8.
This was my thoughts exactly, in addition to physical/mechanical brakes
New to the BMS config settings on xiaoxiang. The delta is a bit high, so I set the balance to aim to balance to a delta of 15mv.
Cells started balancing after settings were changed, however only 4 cells seem to be balancing. I monitored for about an hour and no change. Same 4 cells balancing.
Can anyone help me with what this means? I expected all the cells to begin balancing.
I tried balancing when charging only and also when not charging. Same 4 cells will initiate balancing.
āBalancingā in the context of the typical BMS, LLT included, is simply bleeding energy off of cells (groups) that are in a higher SOC than the others. Static balancing (not when charging) is a slow process and can take a day or more depending on the delta.
Leave it on static balancing and check tmrw. The delta should be much reduced.
