New Rolls Surrette l16's Not holding charge

Welcome to the forum Scott,

I think these are your batteries:

https://www.solar-electric.com/rolls-surrette-s6-l16-hc-deep-cycle-battery.html

4x 6 volt batteries in series? Any Parallel strings?

Details matter here... What are the charging settings (absorb voltage setpoint, float set point)?

When you had them on 4 hours of absorb, did you take a voltage reading on the battery bus?

Have you compared your settings to the Rolls manual?

https://www.solar-electric.com/lib/wind-sun/surrette-manual.pdf

Rolls tends to specify higher charging voltages for their flooded cell batteries (~30.00 volts @ room temperature, vs 59.50 volts for other brands of FLA batteries).

Do you have a hydrometer? Have you measured and logged all of the cells (as received, when "Full", after corrective Equalization Charge--If needed)?

https://www.solar-electric.com/search/?q=hydrometer

At the end of the absorb cycle (4 hours), what was the charging voltage/current? (End amps from Rolls is around 2-3% of battery bank 20 Hour AH capacity--i.e., 100 AH = 2-3 amps rate of charge near end of absorb cycle)

What is the battery bank voltage when you are "concerned"... Around 25.4 to 25.8 volts is usually "full charge" for a resting FLA battery bank (vs ~29-30 volts when charging and 27.00 volts "float").

Where (roughly--Nearest larger city) is the system installed?

What size solar array do you have (3,500 Watts)?

On a cool/clear spring/fall day, your system would output a typical (best case maximum--a few days a year) around:

• 3,500 Watts * 0.77 panel+controller derating * 1/30.00 volts absorb charging = ~90 Amps

And the typical Outback FM80 Controller, would be limited to 80 amps maximum (it is normal to "over panel" an MPPT charge controller to allow for hot panels with reduced Vmp-array/Pmp-array).

Anyway--More questions than answers at this point.

-Bill