BPI Nickel-Zinc 1.6V rechargeable battery 5 2500mWh milliwatt-hour BPI nickel-zinc 1.6V rechargeable battery, no. 5 rechargeable battery, fully charged storage for half a year, there is still power remaining, high capacity 2500mWh, civil high-voltage battery, low internal resistance below 30 Ohm, 1.6V