Cell balancing problem 5x90Ah LioFePO4

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anders-h asked Dec 26, '19

Cell balancing problem 5x90Ah LioFePO4

Hi everyone,

I´ve been using 5x90Ah 12v LioFePO4 in my boat for five seasons now.

This summer I experienced some problems for the first time. When SOC goes down to 50-60% voltage drops to approx 12,5 volts and the BMS shuts down the system.

I´m convinced i have a cell balancing problem here and that the battery with with the worst unbalance is the one making the BMS shutting down the system.

I have the NON smart batteries and looking for a solution to be able to measure cell voltage on my batteries?

Otherwise it´s a "needle in a haystack" trying to find which of the five batteries suffering from cell unbalance..

question nr 2 is how to restore cell balance?

Charging every battery stand alone connected via bms 12/200 or just straight on the battery with a suitable lithium charger (4-5A)?

battery charging battery capacity

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Answer 1 · 2019-12-26T23:35:49Z

Daniël Boekel (Victron Energy Staff) answered · Dec 26, 2019 at 11:35 PM

Hi @Anders H

You can try a long charge on low current to balance the batteries:

https://www.victronenergy.com/upload/documents/Manual-Lithium-iron-phosphate-(LiFePO4)-battery-EN-NL-FR-DE-ES-A5.pdf

to really test the batteries: discharge them one by one and see how much capacity they still have.

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Answer 2 · 2019-12-28T21:49:50Z

anders-h answered · Dec 28, 2019 at 09:49 PM

Thanks for feedback! How do I test the capacity that is left after discharge?

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