4S BMS 30Amp Board Input Voltage

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4S BMS 30Amp Board Input Voltage

Hi People.

Got a 4S BMS 30Amp Board.

What input voltage min max will I need?

No specs with it, do I just put 16.8 into it?

Ive searched google but dont see anything.


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There's no minimum input voltage into the BMS, if too low it will just not work and if too high it will cut-off.

A BMS is a circuit which works as interface between a battery and whatever charges or loads it and so, by itself alone it needs no voltage. The BMS characteristics are chosen to fit the battery or set of cells chosen, with most common values for full charge and discharge of li-ion being 4.2 and 2.5 V per stage. BMSs are built around some control integrated circuit, looking for it on the board and noting down its chip markings will serve to find its datasheet. This should answer between a truckload and a boatload of questions.

The current handling of the BMS is specified with some typical and peak values, usually related with some sense voltage fed on the control chip via the onboard MOSFETs' VGS or some sense resistor. I say this because to me a 30A BMS is something which can work at that current rate, but sometimes I've seen BMS circuits advertised using peak current values.

Hope this can answer most of your doubts.

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A 30A bms probably only handles 15A continuous. As was said, the 30A is a peak value. As far as input voltage, the IC runs at 5 volts and the bms has a preset voltage threshold for turning off the output (for 4S like 14.4v?). Input voltage just has to be high enough to keep that from tripping. You also need to supply adequate charging voltage to it.