Voltage dropping at SOC 40%

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donnyv asked Jun 25, '21

Voltage dropping at SOC 40%

Hello,

Setup is 3x 100ah lithium batteries. Everything is Victron equipment. BMV, BatteryProtect, Multiplus, OrionSmart, and MPPT.

Yesterday I kept my Van inside a factory for the day/night, and today I noticed I was unable to draw power from the battery. Checking the BMV, on the SOC I see it was reporting around 41%, and the Voltage was 10.4V. Checking the BatteryProtect for DC I confirmed it was receiving low Voltage and was in the inactive state. I don't have a Bluetooth for the inverter but the low voltage LED was on.

I wouldn't expect the voltage to drop at SOC 40%. Can anyone advise if this is expected?

A fews things to note, in my BMV history I noticed it said last time at full charge was a day ago, this is not true. I have not hit a full charge in since powering everything on. Could this be a problem? I'm still in process of Van build and haven't been able to drive it much or put it in the sun during the day.

It's been on for about a week with no issues. The SOC was averaging 55%-65% during the week.

BMV Battery Monitor battery system voltage

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Answer 1 · 2021-06-26T00:38:30Z

Jesse answered · Jun 26, 2021 at 12:38 AM

If this is a Lithium setup then that's a dangerously low voltage. I'd have some alarms set to go off if you ever reach 12V, that's already low enough you wouldn't want to do it every day.

Can you show us your individual cell voltages? If they're safe (within 0.1V of each other say) then need to start charging your system asap.

You need to fully charge the battery first to let the BMV know when you're at 100% (synchronise) otherwise it has no clue. Currently your battery is likely at 0%. Not good.

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donnyv commented · Jun 28, 2021 at 01:40 PM

Hi Jesse, thanks for the input. I'm working on a full charge. I'm not fully in the van yet so getting time to run and drive it are a little tricky for the OrionTr charge. But ill get it done.

Not sure how to check each cell individually without opening the battery. Is that what you are referring to?

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