Battery pack balance

At the moment, as the old cell picture isn't avaialble, I can only go on the lights on the battery packs - and at a state of discharge (well the inverter has gone to idle at 7%, and isn't' supporting the house any more) - I noticed that the pack lights don't match. One pack is showing one light on (plus the status light), as expected as it's discharged; but the other is showing two lights (plus the status light).

So I am assuming the two packs are not balanced properly?

How can I initiate a calibration discharge and re-charge to see if that helps?

(2 x 5.2 kWh)

GrahamRead I have an 8.2 & a smaller 5.3 added recently. My battery lights on the 8.2 reduce while the 5.3 shows 4/4 lights on, as though the bigger battery discharges first, while the smaller one stays at 100%, until it starts to discharge when the bigger one is empty.
(no idea what is normal behaviour?)

Have two 5.2 batteries, and they charge/discharge in tandem, i.e. the number of lights on each match.

I have two 8.2kwh batteries and they seem to discharge in tandem with the Master often one green light less than the slave. (AC3.0 plus SolarEdge)

I forced a re-calibration (discharge and re-charge), and that seems to have resolved the issue - both batteries are discharging in tandem judging by their status lights - with both at one when fully (4-7%) discharged.

Hmm, I notice balanced has drifted again ? - with the combined batteries at 5%, one (the master) is flashing green - empty, while the other is showing two green lights.

from a few other appends / reading the tea leaves i get the impression improvements are on the way - fingers crossed

What BMS firmware?

I saw that issue more with 3002. Less with 3005 but still see them slowly drift over a few days of not fully cycling the batteries.
Say there is only enough sun to get to 30 or 40% for a few days. They start to wander. One of the 3 at 2 lights, one flashing as you describe.

Then a full charge and they align again. So it is better.

Previously once they drifted, one would fail to charge at all.

TheDragon (GivEnergy) this would suggest they don't float amongst each other very well, which is a bit weird. I have a set of Pylon (ancient ones) and if you switch one off or say add another, they'll discharge/charge from one another until they are all the same.
Would have thought the voltage difference alone would do this amongst the packs but sounds like the BMS holds them back for some reason or another.

Edit: thinking about it this may also be a side affect of the SOC drift people are experiencing - if the BMS isn't too confident on what the actual SOC is in each pack then balancing multiple packs I imagine becomes an impossible game of cat and mouse...

There is an update coming around the end of the month I read to sort this issue out.

Mal-Givenergy

Is this BMS version 3007? Or is there another sine that

Rather than having to force a re-calibration periodically, would it be more energy efficient to occasionally let the multiple batteries discharge to minimum due to the house load, then when you do have good solar output let them charge to 100% and leave for an hour or so to balance without other energy diverters taking the excess solar?

Can anyone confirm whether a forced re-calibration causes the inverter to output at full power until the batteries are fully discharged, or at the rate set by the house load? Is it possible to set the maximum discharge and charge rates before triggering the re-calibration?

Simon_C as far as I've seen during recalibration the force discharge is at maximum rate - so any excess goes to the grid. When I've done it previously I've deliberately plugged the car in to soak up the excess.

GrahamRead could you slow the discharge rate in the settings though?

Not sure if it would use that setting, but maybe worth a try.

The forced charge if it accidentally gets to 0% uses the set charge rate, and you can change that rate during the charge too.

I've got two 3k inverters, each one is connected to a 5.2 battery. One of the batteries just sits there all day at 100% SOC. Despite the house pulling 5kW, the solar is delivering somewhere between 1-2kW and the system is pulling the balance from the grid, instead of from the second battery. This has been the situation for weeks, despite my back-and-forth with Tech Support to find out why.

Meanwhile, we've getting a new app...

JJB

Are both Inverters at latest firmware.
Are both batteries on BMS version 3005 or 3007?

TheDragon (GivEnergy)

No, they are not, as recommended by the Tech Team at GE. Here's what they are saying about "Plant" systems:

"This is due to the very unique way in which inverters are logged into our database, up until very recently with the removal of some back end systems and new backend inverter logic it was not possible, the teams are actively working on improving dual inverter logic this year, this technology is in its infancy still as it is, but the "plant" setup of two systems is still very new. Although it may seem very basic it is far more complex than it may look on the surface in the back end of it all.
​
We have the new release of our inverters + batteries over the next couple of months along with our EV charger and new app all of which has had significant work from our engineers, I do believe following this more emphasis will be put onto the dual system to bring better integration into our apps and monitoring."

I did send an email to the Tech team yesterday, along with my installer, and whether it's linked or not, after sitting idle for the previous hour, the battery then began to discharge.

I don't think it's too much to expect a setup I paid over £10k for to work as advertised. And even if it's still "in beta", the sense that GE are dragging their feet and prioritising other features, which I consider to be non-critical, is a regrettable.