PeteandSueMarkiewicz Basically I have 2 batteries each with their own inverter and I believe the system is set up so that they are running in parallel to each other and up till recently they’ve been fairly evenly matched in both charge and discharge. Should I expect wide variations in the amount stored in each battery?
Ah right, that wasn’t clear that you have two inverters each with their own batteries, that truly is a parallel system.
Unless you have an AIO with the gateway controlling the two AIO’s, or you have one of the new EMS’s to manage the two inverters together then the two inverters are not connected in any way. This is the same setup I have, two Gen 1 hybrid inverters each with their own batteries.
Because the two inverters are not connected together, they both share house load, and both will charge and discharge independently of each other. In the summer where you’re generating lots of solar and the batteries are getting full every day and relatively little use overnight, I’d expect that you don’t really notice the independent nature of them. During the winter with higher and longer house load I can see why they have drifted apart more.
In your case I doubt that a battery recalibration would add anything as the inverters are controlling the batteries independently. It’s only worth recalibrating if the inverter has lost track of the battery SoC and you see sudden drops in battery level. Best practice is to try to regularly cycle the batteries between full and empty, that way the battery management system can keep track of the battery level.
I find with my two inverters that one tends to take the lead on discharging ahead of the other one, and I do get a gentle cross charge from the first to the second, resulting in the second one filling up at the expense of the first one discharging. You could well be seeing that happen as well contributing to the battery imbalance. When the first one gets totally empty the second will of course continue discharging to meet house load.
