BMS just for voltage cutoff when charging? No Balancing

Does anyone know of a really simple 10S BMS that’s only purpose is to cut the circuit from a simple laptop brick style charger when the battery reaches 42V?

I.e I don’t want it to do balancing of any kind as this adds a lot of extra wiring to my build that I don’t really think I need as my battery is made out of 10 separate, easily removable 1S6P 18650 packs so I can balance them separately when necessary.


I dont think you even need BMS for this, but I might be wrong :slight_smile: Not an engineer…

for that u dont need bms. open up the charger see if u can dial the voltage to set 42v exactly. than just plug in

Do standard “dumb” chargers like this one actually cut off the voltage when the battery reaches 42V?

I had just assumed you still needed some form of BMS to cut the circuit when the battery reaches a specific voltage unless you use something like a hobby balance charger?

I think this one cuts off when the battery reaches 36V…

When you are using BMS with brick charger, the charger limits the voltage and the BMS balances all the cells to be equal, tahts how I understand that :slight_smile: There are also some protection circuits in the BMS limiting the max voltage :slight_smile: which can be a problem when you are regen braking on a full battery

Sounds like you don’t need a BMS at all. If the charger is at 42V, once the battery reaches 42V it will stop drawing current and basically stop charging. The (end-to-end) battery voltage will never go above the charger voltage. HOWEVER if any of your cells or P packs are weak, then the other cells/p-packs will overcharge to compensate for it, that’s what the balancing prevents

edit: When I say “weak” I don’t even necessarily mean weak, just relatively slightly weaker than the other ones. So in effect there is some self-balancing action happening because once one gets a little weaker it will overcharge the others and once they get slightly damaged and take less of a charge, they will be back in balance again. A bms just does this balancing without damaging anything.