I have installed 3 ARK2.5H batteries together with the Growatt BMS and a SPA10000TL3 BH-UP inverter in my house. I already had a single phase SolarEdge solar panel system HDwave 4kW, (unfortunately not possible to have a 3 phase system because I could not install enough panels at the time).

This worked fine together, the Growatt charges the batteries when my current from the grid is negative (during the day when there is sun), and discharges at night. I have checked this for a few weeks and works perfect, the Growatt keeps the use at 0W by feeding back into the grid at the same time.

I recently added a 4th battery to make it a 10kW system, and although I didn't check it as often as before, everything seemed to work fine. Most of the time still had enough capacity left in the morning. So now this week I added a 5th battery to make a total of 12,5kW, but now in the morning the batteries were completely depleted. Strange enough when I went to bed the capacity was at 81%, and while using about 220W continuously during the night, at around 4 oclock in the night the battery level completely dropped to 10% while at that time it should have used max around 1,5kWh total. I checked today during charging, and as it slowly rose to around 36%, it suddenly jumped to a 100%. I have no idea why this now happens. The voltage is correct at 265V total for 5 batteries.

I also disconnected the last battery to test, but it didn't change a thing, except for lowering the voltage to around 210V. Anyone an idea on how to solve this?

Are the batteries communicating with one another? I would think that so many batteries is series, if not communicating, one of them could very easily go out of sync. 

Voltage can not be used to indicate SOC on lithium. Ive tried it. 

How is the equipment wired together? And where do you get the SOC reading from?

they are all linked with ethernet cable which is supplied with the batteries, I would suppose the inverter or the BMS would give some kind of error if there was something wrong or not communicating. Anyway it is getting worse, today at 12 at night it was still around 90%, then it lasted only 1 hour before dropping to 10%. The SOC is the same both in the app as on the web interface. using only around 200W

as a test. disconnect the batteries from one another. and see what the SOC indicators indicates for each battery. 

strange enough I removed the 2 new batteries yesterday, and now everything works perfectly again, after using all night on the batteries, the capacity was still at 50% this morning. So for some reason when I change the capacity from 7,5kWh to 12,5kWh the BMS doesn't charge/discharge correctly anymore. 

I don't understand why, there is no setting adjustment needed as far as I know, and the battery voltage is detected immediately by the BMS when connecting the 2 extra batteries (goes from 156V to 263V), and the individual batteries measure over 50V, so all seems okay. Still with 5 batteries nothing really works anymore.

This morning:

Way different than yesterday...

 

Edited September 15, 20232 yr by xyntec

 

as a test. disconnect the batteries from one another. and see what the SOC indicators indicates for each battery. 

I do not have SOC lights on the batteries, they are Growatt ARK2.5H A1 batteries and are meant to connect to the GroWatt BMS which has a minimum of 3 batteries to work, and a maximum of 10 batteries. It is a system like in below picture (although there are only 2 batteries in the picture which would not be possible I think)

Edited September 15, 20232 yr by xyntec

Whst is the bms in your battery 

Any update ? Probably I have same issues

Interesting

It's probably because the new batteries were not installed at the same soc as the existing.

Actually the issue was that the later battery levels weren't exactly the same as the already installed ones. Even though it was only like a few 10th of a volt, apparently this caused the problems, so i bought an electronic pwer supply, measured the exact voltage of the existing batteries, and charged the new batteries overnight to the exact same voltage and after that connected them, since then i didn't have anymore issue, and every time i bought a new battery charged it before connecting, and now have a total of 8 batteries working great

20 hours ago, xyntec said:

Actually the issue was that the later battery levels weren't exactly the same as the already installed ones. Even though it was only like a few 10th of a volt, apparently this caused the problems, so i bought an electronic pwer supply, measured the exact voltage of the existing batteries, and charged the new batteries overnight to the exact same voltage and after that connected them, since then i didn't have anymore issue, and every time i bought a new battery charged it before connecting, and now have a total of 8 batteries working great

That's essentially what I said, but not quite.

Battery voltage is not the way to do it as the charge curve is very flat most of the time. The batteries have to be at the same SOC when added. It's to do with the capacity within  the battery not the voltage.

The easiest way of doing that is either to fully charge the existing batteries to 100% SOC and also the new ones then add them, or find the SOC of the new ones and then drain or charge the old ones to the same SOC.

The BMS will cater for some small differences in SOC of each pack and then make them all to be the same.

 

Edited November 30, 20241 yr by Tinbum