How many charge/discharge cycles are supported?

The number of cycles is not fixed; it depends mainly on how deeply the battery is discharged each time (DODGlossary · BatteriesDepth of Discharge (DoD)The share of a battery's capacity that has been drawn in a discharge, where 100% means fully discharged.) and on temperature. The 300–800 range usually refers to deep discharges. With shallower discharges, for example to 30–50%, the same battery can deliver many more cycles. So when comparing batteries, check at what DOD and temperature the manufacturer states the cycles.

In a UPS, cycles are rarely the limiting factor. The batteries spend most of their time on float charge and discharge only during outages, so they age mainly with time and temperature. In normal use they are usually replaced every 3–5 years, before they run out of cycles. Cycles matter much more in solar and off-grid systems, where the battery is discharged every day.

The common mistake is designing a daily-use system so that the battery is fully drained every night. With more capacity and a lower DOD, the battery lasts much longer. For frequent, deep cycling, consider types designed for it, such as GEL or lithium.