Capacity Estimation and Lifetime Expectancy of Large-Scale Nickel Metal Hydride Backup Batteries

We estimated the capacity and life expectancy of 100-Ah-scale large nickel metal hydride backup batteries. The proposed method is based on the correlation between the voltage drop after charge cessation and the capacity of degraded batteries. The magnitude of the voltage drop varies with the environmental temperature, but a method of offsetting this temperature dependence is described. Capacity estimation is now possible under the environmental temperature between 0°C and 50°C.