Calculating the battery runtime?
A battery can either be discharged at a low current over a long time or at a high current for only a short duration. At 1C, a 10Ah battery discharges at the nominal rating of 10A in less than one hour. At 0.1C, the same battery discharges at 1A for roughly 10 hours. While the discharge voltage of lead acid decreases in a rounded profile towards the end-of-discharge cut-off. The relationship between the discharge time (in amperes drawn) is reasonably linear on low loads. As the load increases, the discharge time reduces because some battery energy is lost due to internal losses.
