Parallel battery charging with different bms

[chronosgarage]

I’m sorry if this is a newbie question.

I have 2 li ion battery, 20S9P and 20S12P. They have a different type of bms. The 20S9P battery have a common - for charging and the 20S12P have a different - for charging.

If i parallel the 2 batteries, how do I connect the charger? Because if I parallel the 2 battery, the - (negative) of the battery output from the 20S9P will also be connected to the - charging charging port of the 20S12p.

What do you guys think?
Any help is appreciated

 

[Chalo]

Charge them together (in parallel) and discharge them together. That will keep them operating as a single pack.

 

[john61ct]

Are you planning on creating a relatively permanent pack from the two sub-packs, keeping them in parallel during use most times?

 

[chronosgarage]

Are you planning on creating a relatively permanent pack from the two sub-packs, keeping them in parallel during use most times?

Yes, that’s the idea.

 

[chronosgarage]

Charge them together (in parallel) and discharge them together. That will keep them operating as a single pack.

Yes. My question is how to wired the charger on the 2 battery.

 

[goatman]

id adjust my charger voltage to 4.15v/cell. 20s would be 83v instead of 84v or 4.1v/82v and charge both packs while theyre paralleled together. that way the bms wont become an issue while charging

you can always balance charge the packs separately once a month or whenever, are you still using the recycled batteries

this is how i connect to the charger

 

[chronosgarage]

id adjust my charger voltage to 4.15v/cell. 20s would be 83v instead of 84v or 4.1v/82v and charge both packs while theyre paralleled together. that way the bms wont become an issue while charging

you can always balance charge the packs separately once a month or whenever, are you still using the recycled batteries

Yes, i’m using a recycled 18650 from laptop battery. I’m using 1.2A active balancer permanently connected to the battery to supplement the bms.

 

[john61ct]

Are you planning on creating a relatively permanent pack from the two sub-packs, keeping them in parallel during use most times?

Yes, that’s the idea.

Then connect the 1S cell-level groups between packs, and just have one BMS manage it as one integrated pack for monitoring

and balancing if you use BMS for that.

 

[chronosgarage]

id adjust my charger voltage to 4.15v/cell. 20s would be 83v instead of 84v or 4.1v/82v and charge both packs while theyre paralleled together. that way the bms wont become an issue while charging

you can always balance charge the packs separately once a month or whenever, are you still using the recycled batteries

this is how i connect to the charger

Thank u for your reply. I will do that.

 

[chronosgarage]

Are you planning on creating a relatively permanent pack from the two sub-packs, keeping them in parallel during use most times?

Yes, that’s the idea.

Then connect the 1S cell-level groups between packs, and just have one BMS manage it as one integrated pack for monitoring

and balancing if you use BMS for that.

Thank you, that’s a great idea.