Different voltages series charging individual bms

[sobotek24]

[hello.. ive been seeking for this answer trough the search engine and cant seem to find it..

my question is:

Can i charge batteries in series of different voltages each with their own bms while being connected in series..

first battery 4s with its own bms (charging trough bms)

second battery 10s with its own bms (charging trough bms)

i dont know if im making any sense so i attached a pic

 

[amberwolf]

Yes, as long as the chargers have isolated outputs from their inputs.

Isolated means there is no electrical connection at all from any wire on the cord to the wall to any wire on the charging side.

You can test this with a multimeter set to 200ohms, with teh chargers not connected to anything. Check with the black lead of the meter on each wire in turn of the AC side, and the red wire in turn on each wire of the charging side, so that you are checking all possible combinations.

If any wire on the AC side connects to the charger side, typiically the AC ground or AC neutral to the charger negative/ground, then when you connect them to the pack the one on the more positive side will short completely across the one on the more negative side. At best you blow fuses on pack and charger, at worst you start a battery fire.