circuit solutions how to switch battery packs correctly AND achieve galvanic isolation

Thread Starter

krishnasai228

Joined Apr 1, 2022
3
Hallo,
I am doing a project to charger the battery packs, from an IC charger BQ25792,
Generally I am using 3 packs and each can be charged one at a time by the IC charger and others are discharging.
I need to connect the battery packs in order to achieve galvanic isolation and also circuit solutions how to switch battery packs and achieve galvanic isolation so that the switch can seamlessly switch accordingly.
I used the switches as N- MOSFETS

Could you please tell me any solution in detail and i attached block diagram.

Thanks,
Saikrishna reddy
 

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crutschow

Joined Mar 14, 2008
34,392
If you need total isolation between the two grounds (why is that?) then you will need to use relays, either mechanical, or solid state relays that use optical coupling for the control signal.
 

Thread Starter

krishnasai228

Joined Apr 1, 2022
3
Thanks for the reply,
Is it better to use relays or semiconductors like mosfets?,
Can i able to use mosfet to achieve galvanic isolation?
 

crutschow

Joined Mar 14, 2008
34,392
Is it better to use relays or semiconductors like mosfets?,
Can i able to use mosfet to achieve galvanic isolation?
To use a MOSFET, you would need to use an isolator to switch it, such as a opto isolator, or an SSR (Solid State Relay) which has the opto isolator built in.

Relays are already isolated since the contacts have no connection to the actuator coil.

As to which is better, the MOSFET/isolator would be smaller and have a longer life.
The relay is simple, but is larger and takes more power to actuate.
 
Last edited:

Hymie

Joined Mar 30, 2018
1,282
One observation, you have used double pole switching to isolate each battery in charge and discharge mode – whereas single pole switching will suffice.
 
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