pumba avatar image
pumba asked

Initial charging Smart Lithium cell balancing way off

I have just got 3 X Victron 150A Smart Lithium batteries. I was advised to initially pre charge them with a Blue smart 12V/15A charger, set to lithium and charging at (4 amps not 2 edited) amps. Charging the first battery, went fine and ended with 13,44V and all cells at 3,36V stating "Ready for use". The next battery got to 14,06V and stated "Busy, charging disabled" and cell voltage at 3.90V 3.38V 3.37V 3.41V. After removing the charger, all cells next morning was on 3.32V and stated "Ready for use".....The last battery done just about the same as number 2............What am i doing wrong or is the 2 out of 3 batteries faulty?

Lithium Battery
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1 Answer
nebulight avatar image
nebulight answered ·

it's hard to say faulty, but for sure they are out of balance. Either cell one has a reduced capacity (faulty) or it's just at a higher SOC than the rest (unbalanced). I'd make your dealer aware before you try anything.

As for charging at 2 amps, I didn't think the blue smart could do 2 amps, I thought it was 15 or 7.5 amps? The reason you'd want a slow charge would be to charge at LOW current in order for the cells to balance. I don't know how the new active balance works on the smart batteries, but previous passive balance would only start at a certain voltage but could only balance at a low rate. If you are charging faster than the battery can balance on an unbalanced pack, you'll end up with an over voltage condition.

I have a DIY pack with raw cells and what I do yearly is take a power supply that you can get a VERY low current like .5 amp and set it to your bulk voltage until the cells are balanced (top balance since my install is an off grid and spends most of it's time at the top). At that charge rate, the battery will balance itself faster than your charge rate with my BMS. Your mileage will vary with the smart batteries as I don't know they balance rate.

I would still bring this up with your dealer.

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