BMS for Li-ion NMC battery pack configured as 14S18P 48V 120A

Battery Management
1

Hello,

I’m currently working on a Li-ion NMC battery pack configured as 14S18P (~48 V nominal), and I’m actively looking for a solution or design guidance to develop or adapt a suitable BMS for this configuration.
Here are the main constraints and goals of my project:

  • The pack consists of 14 series groups of NMC cells, so the maximum voltage is about 4.2 V × 14, and the minimum voltage per cell must also be properly managed.

  • I’m looking for a BMS that can provide:

    • Overvoltage and undervoltage protection for each series group

    • Cell balancing across all 14 series

    • Overcurrent / overcharge and temperature protection

Do you have recommended ICs that can be used to implement these functions?

2

Here is something that I can recommend to you for now given these requirements:

MP2793 | 4-Cell to 16-Cell, High-Accuracy Battery Monitor and Protector with Coulomb Counting | MPS

Please look through the datasheet to see if this works for you. On paper, the voltage works to a max of 86V, it can handle 14 series cells, is capable of passive cell balancing, and has over current/temp protections.

3

If for some reason this doesn’t apply to you, please take a look at the following link:

Battery Monitors & Protectors - Battery Management - Products

This is assuming you are even looking for a battery protection and monitor IC.

Also, if you are interested, please look into some of our dedicated Active Balancer ICs that MPS has to offer. You can cascade these ICs up to the cell counts that you need if desired.

Best,

Krishan

4

Hello Krishan,

Thank you very much for your help and the time you dedicated to me.
Your expertise has been extremely helpful in improving my understanding of BMS management.

I have a follow-up question regarding active cell balancing:

  • At what exact point should this phase be activated?

  • Should we leave the charger current flowing and balance at the same time,
    or should we disconnect the charger current before starting active balancing?

I want to ensure that the strategy applied aligns with the recommended behavior.

Thank you again for your valuable support.

Best regards,

5

Hello, apologies for the delayed response on this post.

Active cell balancing is typically done during the charging phase where energy can be transferred from stronger to weaker cells to ensure cells have a balanced SoC, so there would be no need to turn charging off for any reason.

Balancing while charging helps ensure that all cells are being fully utilized. Not only is overall runtime maximized, but this also minimizes charge and discharge cycles, which increases battery lifetime and reliability.

6

I should also mention that active balancing can be activated during the discharge stage to ensure that all cells are evenly discharged. If the application calls for it, this can ensure that a battery pack is fully depleted.