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bendermichael avatar image
bendermichael asked

SmartBMV reading 100% capacity at 10.5 volts

Hi there. I have a 100ah LiFeP04 battery (Renogy), a SmartBMV monitor (BMV-712) and a MPPT 100/20 controller. I've had this set up for a few seasons with no issues. I just installed a Webasto heater and am tinkering around with it. Today I got an error code on it saying it shut off because it was under voltage (<10.5 volts for more than 20 seconds). My SmartBMV says the battery is 100% full, but the voltage is reading around 10.5 volts. In addition to a few solar panels (not doing much today as it is winter and cloudy), I have a Renogy battery to battery charger. When I turn on the van, the voltage jumps to 14.5 volts. When I turn off the van, it falls back to 10.5 volts. Is this typical behavior? Is my battery just dead?img-9200.png

MPPT ControllersBMV Battery Monitor
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2 Answers
snoobler avatar image
snoobler answered ·

The BMV does not work off voltage. It counts current in and out and computes the SoC. It resets to 100% when the "charged" criteria have been met.


The BMS likely activated low voltage cell protection.


Since the battery is open circuit, the charging to 14.5V with 0 current likely met the "charged" criteria and cause the BMV to sync to 100%.


If the battery is near or below freezing, the low temperature charge protection might also be enabled preventing charging.



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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

After losing the power supply the the BMV shows 100% or just -- depending on the setting "Battery starts synchronized".

You have to make a full charge cycle to synchronize the BMV to 100%.

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