Hello,
Does anyone else have the issue where the batteries levels show 4% and the supposedly stop discharging but the two batteries have two different readings which don’t average to 4%.
So is the app / website wrong or are my batteries set up wrong?
My inverter also show that the batteries still are discharging when the app states they are idle.
Yep. Been seeing it since my July install on my 9.5’s.
One battery pair is significantly worse than the others.
I’ve had some other problems (two replacement batteries, boards, BMS etc) as well but it’s still present.
I believe their “control” uses the voltages and tries to sync them both to within 0.02 volts (or so).
Percentages are wildly out though. One pair I have a 40% split in SOC at times ! The other pair of batteries I can see up to 18%.
It’s infuriating as hell, because the control we use appears to be based off the lowest/highest SOC percentage we see, not each batteries individual voltage. So when one hits full or empty “0% or 100%” (- even though it might not be) it drops the power wattage and takes ages for the other to align. Or it might never align. Rendering unusable capacity that should normally be available.
This pair didn’t complete the calibration cycle properly (it only did the discharge part) whereas the other pair did fully discharge and charge ok.
Yours don’t look as bad as mine and If they catch up and align at the top and bottom end I wouldn’t worry too much. Otherwise I’d contact support. In fact I’d probably contact support anyway.
Are you seeing a big difference in the temps between the two (when charging/ discharging)?
I did start a thread about this “battery pairs charging with 25% difference”
I’ve got the same issue with 2x 9.5 batteries both on 3013, the primary tends to drain quicker and they drift apart as they discharge.
We see divergence but not as bad and just about manageable. At the top end we rarely see 100% charged and they get to about 96 and 98% respectively. Then they sort of stay aligned (within 5 or 6%) when discharging until the bottom end is reached. Then the primary drops away quicker to around the 4% preset whilst the other lags at anything between 8-10%. However, we have seen that when the batteries go "flat" (idle), the primary will drop below 4%, sometimes as low as 1% - not good. As it does that, the secondary also starts to discharge a bit more, as though the system knows there is a bit more to be had. I think this may be what the firmware is trying to do. I tend to intervene manually if I see overall voltage going sub 50v although whether that's right or wrong, I'm not sure. We're still on 3.12 which has been OK ish other than these odd little quirks. I guess we'll need to try 3.15 at some point again soon, although our first attempts failed.
My two batteries' individual SOC % never agrees with the overall SOC no matter the level full, empty, or in between. It does not seem to matter if a calibration is done or what firmware level the Inverter or Battery BMS is at. The difference noticed has been much the same since installation.
Also the two batteries rarely agree with each other either and can be 10% or so different.
I have reported it to Givenergy but they do not seem concerned and up to a point I just live with it and a matter of mild amusement but I am never quite sure which is correct.
I have also known the batteries to go idle at 4% but change their minds a few minutes later and the SOC go back up to 11% and restart supplying power to the invereter.
killythebid My two 8.2 batteries sometimes seem to drift apart on SOC but are always within 0.2-0.3volts of each other, which I think is the important thing. Then they will suddenly agree on SOC much better but I don't know what makes that happen. They are cycled fairly well in winter which probably helps.
wrefordj Voltage wise my batteries are close together most often and occasionally the voltage of the lower SOC (usually the secondary battery) has a slightly higher voltage.
The winter regime of charging the battery nightly on my cheaper nighttime tariff does nothing much for matching SOC for my installation.
As I say I have no idea which of the 3 SOC readings or voltage indications are correct or if it is one of them or none.
On the whole, the system is doing what I would like it to do so that's good but as far as getting good data from the system about its behavior and capacity it is a mystery.
I’ve just had a calibration done on the pair above that were way out.
It’s early days (calibration done last night) but so far the primary is 6% higher than the secondary now (swapped around from before).
I’ll give it a few days and post back if there are any improvements.
