battery voltage different values on all-in-one

[Kava]

Hi,

I recently installed a small system in my off grid beach house.

The all-in-one is a localy branded Chinese 1KW/12v device (FUJI solar) very similar to some MUST devices. I have 700W of solar and 12v 300Ah lifepo4 battery (cheap Chinese, also localy branded).

I connected to the unit using SolarPowerMonitor (unit detected as PV1800) and noticed that there are two different values for battery voltage. One reported by the charger is always 0.4V above the one reported by the inverter. What is this about? It is single unit connected with single wire pair to the battery so this seems strange.

Googled a bit and all I could find were differences in systems with split devices which makes sense.

Attached is a screenshot from SolarPowerMonitor.

I will close the place for the season soon. Should I leave the solar system running with no loads except the all-in-one or disconnect and turn off? The system is installed in the main house so there is the safety aspect as well as the battery health aspect.

BR,
Kava

 

[Bobert]

You will have losses between the charge controller and the inverter even with a aoi unit.

 

[MisterSandals]

One reported by the charger is always 0.4V above the one reported by the inverter.

The correct voltage needs to be measured at rest.

In general, if charging, the charger will read a higher voltage than the actual battery. If there is a load on the inverter (and idle load by the inverter) then the inverter will read lower than actual battery voltage.