Battery Management System

[RockyTam]

Hi, I got a Battery Management System which i need design. there are 3 battery each 12V, i need build a circuit which can select output 12V or 24V or 36V. I have some experience on design 2 battery. but 3 for me is very hard because the common ground make my main control ground floating around....
i know i can use relay totally separate all vcc and gnd, but this cant use for higher current output(~10A). anyone can suggest me how can i solve this design.

many many thanks.

[Signal]

Some circuit diagrams will help us to understand your problem.

[M@X77]

as suggest by Signal post the circuit and some info in addition eg batteries type, if you want use during charging and so on

eg if the batteries are Pb battery, one idea can be that during the charging you can change from serial to parallel using relays

[bobcat1]

Hi

Use LTC4412 from linear with dual mosfet switch (find circuit diagram in data sheet)
use the LTC4412 enable signal to select the required battery (for 3 batteries 3 LTC4412 circuit is required )
connected in parallel
All the best

Bobi