Dear forum members.

I have a problem with my setup: 4x330W PV panels in series, Kodak 3kW 24V OG3.24 inverter, Pylontech UP2500 24V Li battery.

I made my own communication cable thanks to this forum and HennieB84 who posted a picture of the cable ends necessary for this setup, by connecting a phone cable (4 contacts) and an ethernet cable (8 contacts) through sockets with the right cable connections at the back. It worked and I could load my superspecial-priced Pylon UP2500 (5.5 months on the shelf before sold to me) from 75% state of charge (SOC) to 98% SOC in a few hours, readings according to the Watchpower app. After that, however, the battery showed a fault: overvoltage or overcurrent or so according to the LEDs lit on the battery panel. I did not think much about it though.

NOW: I finally got the proper cable (Segensolar) and noticed that the capacity reading is always 100% on the Kodak inverter monitor (4 blocks lit) and on Watchpower app. The battery seems to be working fine, charging, discharging down below 75% and charging again. No further fault was indicated on the battery. The voltage indication on monitor and Watchpower seems fine and goes up and down as one would expect. Same story if I use my old cable again.

More worrying, I measured the voltage across the power cables with a multimeter while battery was being charged with 9A (at a battery voltage indication on monitor and Watchpower app of 27V) and got a multimeter reading of 31V. (Can I trust the reading while current flowing through the cables?) Concerned about the high voltage, I switched off the PV supply and back on again, after which the multimeter showed 28-28.2V. The Watchpower app gave a warning of "line fault" and of "EEPROM fault" in the same time frame (I only saw it 30min later, so not 100% sure about the timing of events). Btw, the current also goes down to zero when battery is full and battery LED shows "idle" when no consumer is on.

My preliminary conclusion is, that there is nothing wrong with the cable and nothing wrong with the battery. However, the Kodak inverter might have a fault responsible for the constant 100% SOC reading and high voltage of 31V?

Any ideas about it and what I should do next? The holiday house is 250km away in the sticks and it is difficult for me to pay constant attention (there is not even a no cellphone signal). I am quite desperate.

Kind regards

Wolfgang

3 hours ago, meyerwh said:

battery was being charged with 9A (at a battery voltage indication on monitor and Watchpower app of 27V) and got a multimeter reading of 31V.

31 V for an 8S LFP battery is 3.875 VPC; the BMS would have disconnected long before that (at 3.60 VPC). So I think that your multimeter is suspect. There may be noise on the battery voltage, confusing it.

3 hours ago, meyerwh said:

noticed that the capacity reading is always 100% on the Kodak inverter monitor (4 blocks lit)

The "state of charge" reported by the inverter is approximate only, and only makes the slightest bit of sense with lead acid batteries. Ignore it since you have an LFP battery. Hopefully, ICC is reading the SOC from the battery's BMS, and is getting a much more reliable reading.

10 hours ago, Coulomb said:

31 V for an 8S LFP battery is 3.875 VPC; the BMS would have disconnected long before that (at 3.60 VPC). So I think that your multimeter is suspect. There may be noise on the battery voltage, confusing it.

The "state of charge" reported by the inverter is approximate only, and only makes the slightest bit of sense with lead acid batteries. Ignore it since you have an LFP battery. Hopefully, ICC is reading the SOC from the battery's BMS, and is getting a much more reliable reading.

Thanks, Coloumb, for your reply! 

What do you think about the Eeprom fault message? Everything seems to working fine, you think one can ignore it? 

18 hours ago, meyerwh said:

What do you think about the Eeprom fault message? Everything seems to working fine, you think one can ignore it? 

No, that is concerning. I don't use Watchpower myself, so I don't know what that message actually means.