HI

Inverter and Solar assistant shows a huge drop in charge on start of load shedding.

Last night at 00:08 the battery was at 93,8 % and by 00:16 45 %. the draw on the battery was only 400W.

As the same thing happened earlier in the afternoon i was very aware to ensure only the absolute minimum was being drawn from the battery.

The battery a KODAK fl5.2 shows all SOC LEDS are burning solid green despite inverter showing 48 % SOC.

What is also strange is how it then charges back to 100% is very large jumps , 20% in eight minutes.

See attached screenshot from solar assistant.

The battery is brand new , installed 1 week ago. The installation is a year old.

Yesterday , i did have a solar technician attempt to create a master /slave battery on this inverter.

the slave battery was showing an alarm light and low voltage lights (2 LEDS flashing) and was hoping that creating this scenario would allow it to charge.

It didn't work as the salve battery switched itself after +- 10 minutes, resulting in the zero SOC you can see on the graph. This was all disconnected and i am now running on the single battery.

Any advice would be much appreciated.

 

regards Mark

 

 

It appears that issue is due low dc cut off being changed to 48V.

I adjusted it and the the initial drop of SOC adjusted accordingly on the next load shedding.

8 hours ago, Mach1 said:

The battery a KODAK fl5.2 shows all SOC LEDS are burning solid green despite inverter showing 48 % SOC.

Presumably, you are using battery type (setting 05) = USE which means that the battery BMS is not communicating SoC and other information to the inverter. So the inverter guesses the SoC, assuming it's a lead acid type, and of course gets it completely wrong.

Its guess does depend on the low DC cut-off setting, but that only adds or subtracts a constant from the guessed SoC (simplifying slightly).

Basically, just ignore the inverter's SoC value, and trust the battery LED / BMS.

It may be possible to get Solar Assistant to talk to the battery BMS, and this might even fix the inverter SoC. That would require a special cable between the Solar Assistant computer and the battery BMS.

Without battery comms, the inverter is guessing SOC based on voltage and won't ever be accurate