Pylontech Batteries 28.5Kw/h (7 batteries 3 x us5000C, 3 x us3000C)
Solax PV Inverter (Energy meter via RS485)
VM-3P75CT (Energy meter)
1 x ESS Charging Schedule (23:30 => 05:30 100% charge)
Problem Statement
The system has been working as expected with the ESS schedule charging the batteries to 100% between 23:30 and 05:30. As of the 19th November the system only charges the batteries to around 75%. Charging starts of correctly at around 11% / per but tails off to 5% and 2% as it gets closer to the 75% mark. At no point over the last week has the system charged to above 77%.
The system configuration has not been changed in months so I am at a complete loss as to why this is happening.
The following is from my excel spreadsheet showing the delta charge rate from the last week
I’m out tomrrow so I’ll give it a go on Thursday. The coldest the batteries have been is 5C as they are in an insulated rack with a heater that cuts in at 5C. The betteries used to be in a plant room in the house but ran out of space to add the two extra US5000Cs. The batteries are in a 72U 19” rack which is insulated and there is a heater. The thermostat may be a bit low at 5C so I will increase it to 10C.
It was my intention, yesterday, to float the batteries to the same level, however the battery behavious has returned to normal and there is no tail off and the batteries charge to 100%. I have checked the SOC of the batteries and the original imblanace is still present.
The weather has got warmer and I have increased the temperature in the cabinet to 10C. I am also changing the heater to one that has a larger capacity and a fan to provide even heating,
