To prevent DC and AC voltage overshoots because of varying solar irradiance and/or load fluctuations, it will limit the charge current already before battery voltage has rised up to the absorption voltage. It will derate the maximum charge current from 100% at 13.5 / 27 / 54V to 10% at 14.4 / 28.8 / 57.6V. These thresholds are not related to the configured absorption voltage.
Hello, knowing this has already been increased a few years ago and is somehow necessary, I'm still wondering about the reasonableness of the fact the voltages are fixed.
In my opinion this should consider capacity:inverter ratio and especially battery type and voltages! Using a relatively small inverter in a big sized lead acid offgrid installation this makes the AC-coupled power pretty useless for charging, although lead acid doesn't care much about overvoltage!
Now let's look at the Pylontech or other 15s Lithium-Storages, that probably don't even have a GX. Their absorption voltage is below 54V so there is no derating at all, although Li can be damaged by overvoltage? Further this means 15s systems can use the full power for charging while 16s or lead acid systems are extremely disadvantaged. Due to the fact that this is for protection I don't understand why some systems can use the full power up to absorption voltage and others cannot.
Can someone tell me the technical background of the fact that the voltages and the derating are fixed and anything else isn't considered? Probably @Johannes Boonstra (Victron Energy Staff)
Thank you very much!
regards,
porcini