how does current-limiting BMS work actually?


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6:10 AM
Apr 28, 2022
Haven't found the answer to this question just googling so i thought i'd ask if there are any battery tech nerds online here who know. How does the over-current function of a bms actually work on a typical e-bike battery? Is it electro-mechanical like a residential circuit breaker? Is it a solid-state device? Does it cut power off after an over-current event, or does it modulate down the voltage to control current below the desired level? Once the over-current event has happened and it is switched off, does it come back on after cooling off or do i need to switch it back on? Is the fuse blown and need to be replaced?

I've been using these inexpensive ebike batteries from unit pack power. Great performance, very little details on their specs sheet, just want to know what would happen in the unlikely event of a short circuit.
hi !
current limit is done by a shunt resistor (2, 5 or 10mohm)
which voltage is sense by the IC (oftenly a sot23 chip called "DW01")
which then switch off the output mosfet ( N type)

regards ....
`Amps are just limited. Cut offs can occur from heat, or low battery voltage, but there is no AH-related cutoff. Look up "shunt mod", but understand what you are doing if you mod this.