Has anyone calculated the overall losses of taking energy into battery storage then discharging it back to use?
Knowledge of that cycle efficiency will aid the decision as to when it is economic to time charge on Agile Octopus for instance.
ie if overall cycle losses are, say, 15% then the Agile price has to be >=15% below standard tariff to be worth doing.
I am losing about 1.5kWh on every full charge/full discharge cycle. I have 2x 5.2kWh batteries. The losses could be due to the BMS or the inverter. Holding a constant charge over several days (to eliminate the inverter losses) I am seeing a decay in the battery % which the inverter tops up every few hours. This works out to be a battery drain of 50-70W, far higher than typical BMS power consumption which I read online to be around 2W per BMS (so 4W in my case).
I have a ticket open with GivEnergy for several months but they just do a test and answer as though the issue is a state of charge/capacity problem, which is a separate issue altogether. They don’t understand the question. I am now trying to seek warranty redress.
Is anyone else seeing a drain of over 50W from the BMS?