SONY CCD-TRV138 - 1500mAh, 7.4V(Compatible with 7.2V), Li-ion - rechargeable battery discharges slowly and progressively when not in use. The self discharge rate is lower than 1% of the battery's capacity per day at room temperature. But when in higher the temperature, the faster Sony CCD-TRV138 will discharge. So please use you CCD-TRV138 Battery in a right way, and take it at somewhere with a right temperature when you not to use it. There more info at: http://www.camcorder-battery.ca   read more »