Knowing if batteries are full...

[CamperJack]

I have a Victron smart shunt that I need to install and tell it that the batteries are full. But I'm having difficulty knowing if they are full!

My batteries are a pair of 110ah Hankook XV110.

When connected to the solar they read 13.8v. When I switch the panels off they never read more than 13.2v with no load. However the float charge is 13.4 - 13.8v.

Is this correct? Are they full at 13.2v? Is a float charge going to be slightly higher voltage than full charge with no charger connected?

I'm very confused and hope you guys can help me out again.

 

[ManTheVan]

I think if they’re reading 13.2v at rest they’re likely to be fully charged.

 

[CamperJack]

I think if they’re reading 13.2v at rest they’re likely to be fully charged.

Is there / should there be a difference between resting voltage and the voltage at float charge?

 

[Richard n Ann]

Is there / should there be a difference between resting voltage and the voltage at float charge?

Yes, resting voltage (after an hour or so) will be 12.6 to 12.8v
Float charge is 13.2 to 13.8

 

[pappajohn]

The over voltage may corrupt the shunts accuracy.
Let them stand for an hour or two with no charge and no load.

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[autorouter]

The SmartShunt doesn't use voltage to work out how full the batteries are. It measures the current (amps) in and out of the battery, minute by minute, measuring the actual amp-hours in and out. It needs to know at the start when the battery is full, so it has a starting point. If the battery charger is in float mode, 13.8V, that sounds like the battery is 100% full.