Have Net Metering. What SOC to charge batteries?

[DIYrich]

I have net metering, so batteries are for backup. The Sol-Ark sends excess solar to the batteries until they are 100%. I understand it is bad to keep LiFePO4 batteries at 100%. Note: 100% is charging to 54.5v, and resting around 53.3v.

Should I:
1) Limit power to Home, and let the batteries draw down to 80%, and then recharge back up to 100% the next day; or
2) Disable charging (set charge amps to 0), draw down the batteries to 80% and let them sit there. (re-enable charging when needed).

 

[BentleyJ]

Its Ok to top up the batteries everyday or every few days at 54.5V (3.4V per cell) so they are charged and ready for an outage. They do not need to be float charged all day. If you can disable Float or set the float voltage low to 53V (not sure what you meant by resting) and Enable the charger for only 2-3 hrs, or whatever time is needed to charge as evidenced by the current dropping off at constant voltage. Also, set the Charge Current low like 0.1C.

We have the same situation, batteries are mostly for back-up as SCE hasn't forced us to TOU yet. The 270Ah battery charges at 54.5V from 1:30pm to 4pm, Current set to 10A tapering off to 0.5A at the end of the cycle.