edsvictronstuff avatar image
edsvictronstuff asked

One battery not charging when other battery hits 100% SOC

I have a situation with my batteries that I hope someone can help me with. My setup.

Slide in Camper

4x100 watt solar panels

Victron SmartSolar Charge Controller - 100/30

2xDLB-G24-12V Lithium batteries

For simplicity, I'll refer to the batteries as 204 and 956 - the last three numbers of their serial numbers

Battery wiring.....

Jumper cable on positives and jumper cable on negative terminals

Connected in a charge/load configuration

shore power connection (charge) -positive on 204 and negative to 956

Inverter Connection (load) - positive to 956 and negative to 204

The situation is this, when 204 reaches 100% SOC the charging stops - both batteries go to an idle state and charge controller goes to a "float" charge.

Currently, 204 is at 100% and 956 is at 62% SOC. I have checked the connections and all are tight. I'm using multi-strand 2/0 cable from batteries to inverter and shore wiring is the same.

I'm suspicious that the charge controller "sees" the two batteries as one and when one shows 100%, then the controller considers them charged.

Why does 956 not continue to charge to 100%? I have the charge controller set to lithium batteries which according to the manual is a preset configuration. Is there a setting in the charge controller that I can change?

Thank you for your help


MPPT Controllersbattery chargingLithium Battery
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1 Answer
David avatar image
David answered ·

The batteries are connected in parallel - and therefore must sit stable at the same voltage. I suggest disconnecting both and individually charging both to 100% then reconnecting them.

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Sarah avatar image Sarah commented ·

Agree. Depending on how the batteries manage internal cell voltage this may take several iterations of the bulk/absorption/float sequence. Once the batteries are independently fully charged (no charge current) is there a way to reset the SOC in the Bluetooth app? It would also be advisable to compare the absorption times between the charger and the battery specifications.

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