question

rangeview23 avatar image
rangeview23 asked

Low voltage high SOC

Hey guys,

Just installed new 100ah battery with Bluetooth 500a shunt. I have set all the parameters up as per the store instructed me to.

Yesterday I had a SOC of 42% and voltage of 10 1 volts-no problems, I'll just charge it the next day. But, before I charged it (the next morning) it read 100% SOC but a low voltage of 10v.

I completely disconnected my fridge and the shunt read 0A then plugged the fridge back in making sure it still draws the correct current when it's running.

Hi is can I have a low voltage but a SOC of 100%?

battery system voltage
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3 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

The SOC is a calculated value, not a measured value. So it needs to be synchronised with the battery at full charge fairly frequently. Also, various efficiency and other coefficients need to be accurately set up for this to track - even moderately accurately.

Far easier to rely on cell voltages.

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kai-fuchs avatar image
kai-fuchs answered ·

If you use the shunt together with a solar system set the charge detection voltage and time high enough. Ive something like 14,0v and 45min with an AGM Battery and it works great.img-1578.jpeg


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jeremy-dinsel avatar image
jeremy-dinsel answered ·

We had two 230 Ah batteries in parallel and saw a low voltage with an above 90% state of charge. Disconnecting the batteries and running a Battery Tester against each of them showed that one of the house batteries had a State of Health of 47% and higher internal resistance. It failed the battery tests. The other had a 100% state of health and a lower internal resistance.

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