Hi @ed209 , I just got my EP500 and having the opposite issue where my battery percentage drops way too fast during standby with AC ON (always on) and DC OFF (always off).
Setting is as follows Time Control Setting:
Charge from 8am to 4pm
Discharge from 4pm to 9pm
From 9pm-8am it is bypass output.
During bypass output (9pm to 8am), my battery percentage drops 1% per hour where it gets to 0% and my system shuts off even if my volt reading is 52.5. I am curious how fast your battery percentage drops during bypass output. It looks like my system is defective.