Mutau Ranch

Reserve is the friendly number: 100% means the batteries are full, 0% means you've used everything you should — time to stop and let the sun refill them.

• The batteries are rated 675 Ah but are ~9 years old, so we count on roughly 500 Ah actually being usable. Reserve is based on that smaller, honest number.
• Lead-acid batteries shouldn't be drained past half — so 0% reserve is set at the 50% mark, not truly empty.
• The power doesn't shut off at 0% — the inverter cuts out when battery voltage falls to about 43 V, somewhat past the floor. But past 0% the voltage drops fast and the shutoff can happen with little warning.
• Big motors are special: starting the water pump can briefly yank the voltage down to the cutoff even with healthy reserve — that's a surge-power limit of old batteries, not empty batteries.

These are estimates, tuned conservatively. When in doubt, the status banner at the top tells you what to do.