Cycle Life

Cycle life refers to the number of complete charge-and-discharge cycles a battery can perform before its capacity degrades to a specified level (usually 70–80% of its original capacity). It is one of the most important metrics for evaluating the longevity of a solar battery.

One cycle equals one full discharge and recharge — though this doesn’t have to happen all at once. Discharging 50% and recharging, then discharging 50% and recharging again, counts as one full cycle. Modern lithium-ion home batteries typically offer 4,000–10,000+ cycles depending on chemistry and depth of discharge. Lithium iron phosphate (LFP) batteries generally have longer cycle lives (6,000–10,000+ cycles) than lithium nickel manganese cobalt (NMC) batteries (4,000–6,000 cycles). If a battery cycles once per day, 5,000 cycles equals roughly 13–14 years of use. Most battery warranties are expressed in both years and cycles — for example, “10 years or 4,000 cycles, whichever comes first.” When comparing batteries, consider both the cycle life and the guaranteed capacity retention at end of warranty.