[Ether]

Originally Posted by MrForbes

Have you considered replacing the normal FRC battery with a car battery? It would have about 4 times the "reserve capacity", so you wouldn't need to charge it as often.

From Wikipedia, FWIW:

A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharging only a small part of their capacity.

The structural difference between deep cycle batteries and cranking batteries is in the lead battery plates. Deep cycle battery plates have thicker active plates, with higher-density active paste material and thicker separators. Alloys used for the plates in a deep cycle battery may contain more antimony than starting batteries. The thicker battery plates resist corrosion through extended charge and discharge cycles.