victron BMV-712 resetting to 100% when inverter turned on

I have the BMV-712 battery monitor seems to be working correctly, but I am having an issue with it resetting the SOC to 100% when I turn the inverter on. I have a multiplus 2- 5k. When I am not at the house for a couple days I have been turning the inverter off so it doesn't burn power at idle. Sometimes, when I turn it back on the BMV-712 suddenly resets to 100% charge. Wondering if it is a voltage spike causing it? Thinking maybe change the charge detection time? Anyone else encounter this?

change settings in BMV to "keep SoC"



If the act of turning the inverter on is somehow cutting power to the BMV, and you have that option set to "set to 100%" it will reset to 100% when power is lost.

Without more detail on your system, it's difficult to guess at what's causing a power interruption if that's what's happening.

There is not much to the system. It is just the multiplus the BMV-712 and two eg4 lifepower batteries. That is it. No solar or anything else in the system. I did change it to keep SOC on reset. Will see if that resolves it.

Are you just power cycling the inverter and not the batteries or an interim disconnect?

sunshine_eggo said:

Are you just power cycling the inverter and not the batteries or an interim disconnect?

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I don't know what this means. I am in the processes of building my house. I have not yet hooked up the solar. I am off grid. I have the inverter and the batteries and then approximately 10 days when the batteries get low I turn on the generator and recharge them. It is very basic.

squarpeg said:

I have the BMV-712 battery monitor seems to be working correctly, but I am having an issue with it resetting the SOC to 100% when I turn the inverter on.

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How? Are you using the physical inverter switch?

Are you doing anything else like turning on/off the battery at its breaker/switch?

Do you have a master off switch that you are switching on/off?

Yes I turn the inverter off by using the on/off switch on the inverter. I leave the batteries on so the BMV-712 does not reset. There is no real load on the inverter when the inverter is switched on or off.

squarpeg said:

Yes I turn the inverter off by using the on/off switch on the inverter. I leave the batteries on so the BMV-712 does not reset. There is no real load on the inverter when the inverter is switched on or off.

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Okay. I was just trying to confirm that you weren't cutting power to the BMV.

So, you can see the lynx SoC the moment before you turn the inverter switch on, but once the inverter is on, it's reset?

Yes

Hmmm... I got nothing. Hopefully, the Keep SoC option will cover it.

Have you ever tried turning it on while running the trends tab in VC to actually watch the graph and see it jump to 100%?

I gave you some incorrect info on this issue. Looking at the "trend" screen of the smart shunt. It is not exactly when I turn the inverter on or off. It is when the battery bank is in a high state of charge (above 90%) and when I remove all the loads from the inverter. In looking at the voltage vs charge what I am seeing is any rise over 53 volts causes a reset. When I am at my house I turn on the inverter, there is a draw on it the voltage drops below 53v and it all appears to work fine, till I go around turn every thing off. Voltage pops over 53v and it resets to 100%. Once the batteries fall below about 90% they never pop over 53v so it appears the shunt is working correctly. In looking at the setting for charged voltage it is set at 52.8v . I think I left that as recommended. Looking at the specs for EG4. The only thing I see is a float rate of 54v. I am assuming that is the charged rate and I should change the setting on the smart shunt. Does that seem right?

This sounds like a configuration problem that's triggering a premature sync.

Proper configuration of the shunt depends on how you are charging?

If charging purely with AC or other consistent charge method (solar is variable), charged voltage should be 0.2-0.3V below the FLOAT voltage of the charger.

If charging with solar, charged voltage should be 0.2-0.3V below the ABSORPTION voltage of the charge.