Can you put 24V packs with BMS inside in series?

[kuranaga]

Hello

trying to buy some LFP packs and the manufacturer tries to convince me that 24V packs with BMS inside can be put in series to make 48V Battery - when there is no BMS connection between the packs (so only positive of pack 1 to negative of pack 2, no other connection between the packs and internal BMSes).

That can't be true? Over time the packs may drift and one have e.g. 26.4V and the other 26.0V... or?

 

[siberianghost]

All depends of bms capabilities, in the specs sheet of the battery should specify the maximum of connections in series and parallel.

To connect two batteries in series you should top balance each one separately.

This ensure the same SOC at the time of connection to later let them discharge evenly.

 

[740GLE]

There are battery balancers on the market to keep banks balanced, it doesn’t take much to try and keep them even.

 

[kuranaga]

All depends of bms capabilities, in the specs sheet of the battery should specify the maximum of connections in series and parallel.

To connect two batteries in series you should top balance each one separately.

This ensure the same SOC at the time of connection to later let them discharge evenly.

but the BMS have NO connection to each other

 

[siberianghost]

but the BMS have NO connection to each other

You don't need to connect physically each bms to make it work. I have 2x 12v 200ah lifepo4 connected in series and works flawlessly but it's supported by the manufacturer.

As I said all depends if the battery support it. Can you post the battery brand and model? so we can confirm what the seller is telling you.

 

[kuranaga]

There are battery balancers on the market to keep banks balanced, it doesn’t take much to try and keep them even.

yeah that might work.

You don't need to connect physically each bms to make it work. I have 2x 12v 200ah lifepo4 connected in series and works flawlessly but it's supported by the manufacturer.

As I said all depends if the battery support it. Can you post the battery brand and model? so we can confirm what the seller is telling you.

Im looking into Bluecarbon 24 packs. but as I say there is no communication between the BMS. only positive connects to negative of the other pack, the manufacturer says it would not be a problem.

 

[siberianghost]

Looking in the BlueCarbon alibaba account they show multiple batteries connected together in their product description. I think you're good connecting two 24v to make 48v system.

If the seller gives you warranty and confirm it you're good to go.

Edit: Also found another forum member using them in parallel

 

[kuranaga]

Looking in the BlueCarbon alibaba account they show multiple batteries connected together in their product description. I think you're good connecting two 24v to make 48v system.

If the seller gives you warranty and confirm it you're good to go.

Edit: Also found another forum member using them in parallel

Their pictures show them only connected in parallel