Question

when lead acid battery gets in deep discharged condition

Answer 1

A deep-cycle battery delivers 100–200 cycles before a gradual decline begins. Replacement should occur when the capacity drops to 70 or 80 percent. Some applications allow lower capacity thresholds but the time for retirement should never fall below 50 percent as aging may hasten once past the prime.

To keep lead acid in good condition, apply a fully saturated charge lasting 14 to 16 hours. If the charge cycle does not allow this, give the battery a fully saturated charge once every few weeks. If at all possible, operate at moderate temperature and avoid deep discharges; charge as often as you can.