Cycle Life of Rechargeable Battery

Cycle life of rechargeable battery, according to national regulation, under condition of fully charge and discharge, battery capacity declines to 70% of rated capacity, that battery’s charge and discharge time is cycle life.

Ignore other factors (like memory effect), rechargeable battery capacity declines to 70% of rated capacity that charge and discharge time is different at different discharge depth. Provided some rechargeable battery, ignore other factors, fully charge and discharge, its cycle life is 500 times, and if for 50% discharge, cycle life will be 1000 times. So slight charge and discharge can not reduce cycle life of battery with low memory effect, for some low memory effect battery, like Lithium Battery, lead acid battery, do not fully discharge before recharge.

National regulation for lithium battery cycle life, under condition of temperature 20?±5?, 1C5A CC charge for lithium battery, CV when voltage reach to charge limitation voltage, until chare current less than 20mA and cut off charge, stay for 0.5-1 hour, then 1C5A CC discharge, cut off when out put voltage reach to discharge cut off voltage, for one cycle. Then stay for 0.5-1 hour and go for next charge and discharge cycle. When two discharge times are below 36 minutes, the battery cycle life is off. After testing, cycle life should be more than 300 times. According to national standard regulation, new lithium battery for mobile phone, 1C5A CC discharge, its discharge time should be more than 51 minutes.

1C5A means C5 is the rated capacity of lithium battery, according to national regulation, is meaning is, in regular environment condition, after charge, 5 hours continuous discharge to 2.75V, that lithium battery output electricity volume, C5A is the unit of current, that battery rated capacity with work time, e.g. 1200mAh battery capacity, C5A is 1200mA, 1C5A is one time of C5A, also 1200mA, 0.1C5A is 120mA, obviously, different rated capacity lithium batteries their C5A are different.

Rechargeable battery cycle life is related to charge time, regular application, charge battery cycle life is related to charge time directly, less one time after one cycle. And for non-normal application, the main factor is over charge, over charge will damage battery cycle life, and another factor is over discharge, that affects battery cycle life.