Putting different batteries brands (same capacity) in series OK?

[black se7en]

Newb question:
Is it OK to put different battery brands in series? I want to setup a 24v system with these two batteries. They're both 12v 100ah as labeled but I think the cell types are different. Prismatic in one and pouch in the other I believe.
Thanks for the help!

 

[robbob2112]

Stringing 12v LFP batteries in series to make a higher voltage can work,, but it is ALWAYS better to buy the correct voltage.

If both BMS have the same amp rating -- not Ah --- how many continuous amps can it put out.. so 100amps is usual, but it can vary on battery... then you can string them together and they will work. you will need to use an external balancer like the HC01 you can get off amazon -- it will keep them with equal voltage. Without it you will have to periodically need to take them apart and charge to full then reassemble them.

Different BMS will have slight difference in the resistance of the negative leg and this will cause the batteries to take a charge unevenly. Prismatic verse pouch will also make them charge unevenly.

So if you choose to do this better to have the same type cells and the same BMS which means the same vendor.

 

[RCinFLA]

Most important is to check each battery spec making sure it is series stackable.

Some cheap 12v LFP batteries are not stackable because their BMS is not rated for the higher voltage. Each battery's BMS must be able to take the entire series stack open circuit voltage during a shutdown situation by the BMS without exceeding the BMS's MOSFET breakdown voltage. 8s BMS's are often built with 40v breakdown MOSFET's, 16s BMS's are built with 80v or 100v breakdown MOSET's. Some cheap 12v LFP batteries have 25v breakdown MOSFET's in their BMS.

If a 12v LFP battery is series stackable it will say so in their specs. If there is no mention of series stacking then you can only assume they are not series stackable.

 

[black se7en]

Thanks @robbob2112 and @RCinFLA !
Both batteries say series compatible and are both rated at 100a discharge/charge, on spec.
I know one of the batteries the BMS has been replaced and is a JKBMS 4S-8S unit. The other battery has the factory bms.

I'll look into that HC01 as recommended! Other questions: would it be "safer" and less risky/better longevity to keep them in parallel to stay at 12v? Or would I still have a balancing issue?

Also, hopefully this isn't too wild of a question but would it be possible/advisable to pull all the cells out and wire it to the JKBMS in 4S2P? Or would having prismatic vs pouch cells not be advisable doing that as they are not factory matched either?

Thanks again, I'm learning a lot!

 

[MisterSandals]

the BMS has been replaced and is a JKBMS 8S unit.

8S is a 24V battery.

 

[black se7en]

8S is a 24V battery.

Thanks for pointing that out! To clarify, what I was thinking was 4S2P if that is possible given the batteries/cells that I currently have and the JK BMS. 14.8V 200ah configuration. (Edited my previous comment to clarify also).

Additional info:
The JK BMS model is JK-B2A8S20P. The BTRPower battery is unaltered and has the factory BMS.

 

[MisterSandals]

JK BMS model is JK-B2A8S20P

Looks like that handles 4S just fine.

I was thinking was 4S2P if that is possible

I have had 4S2P in my RV since 2019. I like 4S2P. Others think 4S x 2 batteries in parallel requires a BMS for each battery.

JK BMS. 14.8V 200ah configuration.

14.8V / 4 cells is 3.7V. This sounds like a lithium ion battery and not a LiFePO4 battery (3.2V x 4 = 12.8V nominal).

This one?

https://www.aliexpress.us/item/3256807736649735.html

 

[black se7en]

Looks like that handles 4S just fine.

I have had 4S2P in my RV since 2019. I like 4S2P. Others think 4S x 2 batteries in parallel requires a BMS for each battery.

14.8V / 4 cells is 3.7V. This sounds like a lithium ion battery and not a LiFePO4 battery (3.2V x 4 = 12.8V nominal).

This one?

https://www.aliexpress.us/item/3256807736649735.html

The batteries that I have are the ones in the picture on my original post. They both say LiFePO4. I mis-spoke on the voltage. (I appreciate your correction, I'm still learning!)

I'm just wondering what would be the best/safest way to utilize what components I currently have for a small camper setup.

1. Run batteries in series for 24v 100ah battery pack
2. Run batteries in parallel for 12v 200ah battery pack
3. Break apart the batteries into individual cells and use 1 BMS (JKBMS) to run all the cells

I just wasn't sure given that they're different manufacturers and are different cell types.
I didn't know if the different cell types (Prismatic and Pouch) would have any issues or major impacts for the 3 different options and which one would be the best route.

The link you posted is similar to the JKBMS I have except the one I have has the HEAT and CAN/RS485 comm options as well.

 

[MisterSandals]

I'm just wondering what would be the best/safest way to utilize what components I currently have for a small camper setup.

If you describe how you expect to charge them (solar and/or alternator) and how you expect to use them (inverter or DC only loads?) then someone should be able to recommend a setup.

Generally 24V is better over 12V when you have an inverter over 2000W since higher voltage keeps the amps manageable.

 

[black se7en]

If you describe how you expect to charge them (solar and/or alternator) and how you expect to use them (inverter or DC only loads?) then someone should be able to recommend a setup.

Generally 24V is better over 12V when you have an inverter over 2000W since higher voltage keeps the amps manageable.

Thanks @MisterSandals !

Currently I have 350W of solar panels I plan on using to charge. I have contemplated adding alternator charging in the future if needed and depending on the cost. I will be using it with a 2000W inverter that I currently have that is 12v, but am open to replacing that with 24v one if I can run those batteries/cells in a 24v configuration safely and reliably.

Use case is to run a small fans, lights, charge cell phones for the most part. I'd also want to be able to run a small fridge (dual DC/AC power capable) for a few days between full charges.

 

[MisterSandals]

2000W inverter that I currently have that is 12v, but am open to replacing

I would only consider replacing a working 12V inverter with 24V if it didn't provide enough power. From your list, 2000W seems like plenty.

What are the specs (power use) of your fridge. Not sure 350W of solar are enough. Where will you be using this (to calculate solar hours)?

 

[Brucey]

2. Run batteries in parallel for 12v 200ah battery pack

This is what I'd go with. To series two batteries with different bms and cell types isn't ideal, when one shutdown before the other etc.