Cagire

Even with a mediocre one, it would still be 27 years of service. I can't imagine such a cheap inverter lasting that long anyway.

It seems like EEPROM is given for 100 000 writing cycles. On average, it will be 1 writing per day (2 when it is sunny and 0 on cloudy days), so we can imagine a life of ... 100000/365 = 273 years. I don't think I will be there to see the EEPROM fail. @Phalanxer I'm not sur what you are trying to explain but I already have my own setup working perfectly. I'm using an ESP32 connected to the inverter via RS485, together with esphome and home assistant.

Well, well, well. Reminder of the idea: I realized that even in "float voltage" mode, the inverter could charge at full power if the target voltage is higher than the battery voltage. In other words, even in float mode, it will not limit the current if the float voltage target is not reached. The idea, then, was to set up an automation to change the float voltage parameter "dynamically" in order to trick the inverter. After quite a few tweaks to the parameters, it seems to be working now. The settings are as follows: When the battery voltage is >28V, set the float voltage at 27.2V. When the battery voltage is <26.5V, set the float voltage at 29V. Notes: Threshold voltages over 28V trigger the overcharge circuit protection on my setup. I prefer to let the voltage drop to 26.5V (around 70%) before going into bulk charge again, to avoid constant back and forth. So far, so good.

I'm digging out this topic because I'm also experiencing premature float bug with my must pv1800. I tried to work around by raising the float voltage setting to 29V. It works. However, if the battery is fully charged and there is still PV power coming in, the inverter will go into fault for overcharging and turn off AC-out. But I had an idea. Since I'm anyway running an esp32 through modbus controller in order to get the data on my home assistant, this morning I set up an automation that automatically sets float voltage to 29V when battery voltage is <28.5V and sets it back to 27.2 when battery voltage is >28.5V. I think it's the perfect counter for this bug. However, I will let it run for a few days and give you a final report on this work around.