Why Single BMS for Parallel-Series LiFePO4 Cells Is a Bad Idea

Discover Why Using a Single BMS for Parallel-Series LiFePO4 Cell Configurations Can Compromise Your Battery System's Efficiency and Safety
Ernest from LiFePO4 Oz as he delves into the complexities of connecting LiFePO4 cells in parallel and series configurations under a single Battery Management System (BMS). This video is a must-watch for anyone looking to understand the potential risks and why it's crucial to consider alternative setups for optimal battery health and longevity.
Why Watch This Video?
-Learn the technical drawbacks of using a single BMS for parallel-series LiFePO4 cell connections.
-Understand the impact of varied cell capacities and internal resistances on your battery's performance.
-Discover how properly managing your LiFePO4 cells with the right BMS setup can enhance safety and extend battery life.
Key Takeaways:
-Single BMS systems can't individually monitor cells connected in parallel, risking uneven charging and potential safety issues.
-Differential internal resistances and capacities among cells in parallel can lead to imbalanced discharge and charge cycles.
-Implementing multiple BMSs or utilizing specialized parallel modules can mitigate these risks, ensuring each cell is appropriately managed.
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Need Assistance or Have Questions?
Our team at LiFePO4 Oz is here to help. For personalized advice or more information about our products and how they can fit into your energy solution, don't hesitate to reach out.
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Remember: Proper battery management goes beyond just the technical setup; it's about ensuring the safety and efficiency of your energy system. By choosing the right BMS configuration and considering the use of parallel modules, you can achieve a more reliable and longer-lasting battery setup.

[@jensschroder8214]

If two cells are connected in parallel then both cells reach the same state of charge.
One 4 cell BMS can certainly be used for a 4s2p battery system.
When there were no primatic cells yet, many round cells were connected in parallel.
These were often used cells with different capacities and different internal resistance.
It was just ensured that the parallel pack had approximately the same capacity.
Then the p-packs were connected in series and and connected to a BMS.
That worked very well back then. But the lithium batteries back then were not as safe as today's LFP batteries.

[@jec_ecart]

Agree. 2p4s and 2p8s battery packs are common and work well.

[@1bdorowd]

I have a problem with my 6 360 amp LFP 48v 15s paralleled banks. Currently I have 6 300amp JBD bms. Is there a module out there to purchase?

[@jec_ecart]

I would recommend that you make multiple small batteries with individual bms and THEN parallel them together.