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Christian Bertschy avatar image
Christian Bertschy asked

Can't charge one of my two batteries above 13.5 V

Hi everyone,

I'm trying to balance one of my two batteries (2x Lithium Batterie 12,8V/200Ah, BAT512120610) in my 24V system, but can't get it above 13.5 V. It needs to get to 13.8V to do so, based on the feedback I get on the Victron connect app:

d91eadf4-3c81-49a7-b140-33f897753f6e-1-201-a.jpeg

I was able to balance the first battery:

54c2f4ba-ebf3-4b90-bb83-3fb1e1925864-1-201-a.jpeg

The temperature difference is due to the one battery being further from the floor.

It seems there is an overall threshold that seems to prevent the second battery to get to 13.8V?
Any help is highly welcome and thanks in advance!

I have a the following setup:

2x Victron Energy Lithium Batterie 12,8V/200Ah - Light - Smart / BAT512120610
Victron Energy EasySolar C 24/1600/40-16 MPPT 100/50 / CEP241621010
Victron Energy VE Bus BMS / BMS300200000
Victron Energy BatteryProtect 12/24V-100A - SMART / BPR110022000
Victron Energy Digital Multi Control 200/200A GX (RJ45 90°) / DMC000200010R
Victron Energy BMV-712 - SMART / BAM030712000R
Victron Energy Venux GX

BMSbattery
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d91eadf4-3c81-49a7-b140-33f897753f6e-1-201-a.jpeg (256.9 KiB)
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

15V is pretty high.
Are the batteries still connected together? If yes disconnect them and charge them separately.

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Christian Bertschy avatar image
Christian Bertschy answered ·

Hi @Matthias Lange - DE

Thanks for your answer! Yes they are still together. What would I need to change on my system if I only hook up one of the two? (i.e. it being then a 12V setup)

Would another approach be then to let both batteries discharge and then try to reload again?

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kevgermany avatar image kevgermany ♦♦ commented ·
The batteries are in series, so same current through both. If you don't fully charge separately, you'll not get it right because the same current goes through both.


You could consider a battery balancer to bring them to the same state of charge. This will then keep them close. Using a balancer to get these in balance will take a while, though as they're a long way out.

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