Deye exceeding Absorption V limit

[kolek]

Deye 8K absorption V is set to 55.2

But today it charged beyond that limit to at least 55.48V according to it's own reading (see screenshot)
The voltage actually rose to 55.69V according to Victron SmartShunt and 55.43V according to JK-BMS.

It's mainly surprising to me that Deye would charge to a voltage higher than it's own sensor reading of the voltage.
Is this normal?

 

[kommando]

There is a lag between reading 55.2V and the inverter taking action, in that lag if the PV output is high then the charge voltage will exceed 55.2V.

 

[kolek]

There is a lag between reading 55.2V and the inverter taking action, in that lag if the PV output is high then the charge voltage will exceed 55.2V.

Interesting, thanks for that tip. I didn't know that.

 

[kolek]

I would have thought that the Deye would shut off the charging process as soon as it detected voltage above the Absorption V setting, apparently not.

 

[kommando]

Your setting is in the neck of the LFP SOC to volts, so small charges have a larger effect than lower down where the line is flat. The inverter is continually balancing charge, demand and production so cannot work to a hard setting without switching off. So live with it or drop your absorption voltage, there is little gain in SOC up in the neck so dropping it 0.5v will lose you little capacity.

 

[kolek]

So live with it or drop your absorption voltage, there is little gain in SOC up in the neck so dropping it 0.5v will lose you little capacity.

Right, I've noticed that the SoC plummets down from higher levels. Is it important to keep charging levels below around 55.2V? If it's not going to do any damage to go to 55.7V I might just leave it.

 

[kommando]

Danger point is 3.65v per cell, your BMS log will tell you if that has been an issue.

 

[kolek]

Danger point is 3.65v per cell, your BMS log will tell you if that has been an issue.

Ok, I'll monitor and consider lowering if I see it repeating this behavior regularly.