Digital camera is a high drain device consumes large amount of power in each click. Digital camera with LCD and flash light can draw over 1000 mA quickly and depleting the alkaline batteries after a few shots. Alkaline batteries have approximately 3000 mAh capacity with a 1000 mA load. So we have to use a high efficient battery such as NiMH ( Nickel Metal Hydride) battery. NiMH battery outperforms other rechargeable batteries and has higher capacity and less voltage depression. The toxic Cadmium is absent in NiMH battery so it is the most Eco friendly one.
Typical NiMH battery is rated 1.2 volts/cell. This is the nominal voltage of the cell that is discharging at the rate of C/10 at 25 degree centigrade to an end voltage of 1 volt. The battery pack has three 1.2 volt cells making a total 3.6 volts. When a fully charged battery is used, the discharge voltage starts from 1.5 volts followed by a sharp drop to 1.3 volts. The voltage in the cell remains 1.3 volts to 1.2 volts until another voltage drop occurs during a deep discharge.
The NiMH battery is similar to NiCd cells in structure but it uses a hydrogen absorbing alloy as negative electrode instead of cadmium. The positive electrode is a nickel oxy hydroxide (NiOOH).NiMH batteries can easily handle the high current levels and maintain their full capacity. AA type NiMH cells have a nominal capacity (C) ranging from 1000 mAh to 2700 mAh at 1.2 volts with a discharge rate of 0.2C / hour.
Important facts to be considered while using NiMH battery are