The Nitecore NL2150i 21700 battery is specifically designed for the Nitecore i Series, including the P20i flashlight. The cell has a capacity of 5000mAh and a maximum continuous discharge of 8A. The i Series battery enables a highly efficient output by minimising the loss of power due to internal resistance. It features a dual way output with positive and negative polarities at both ends, plus a high energy density of up to 240mWh/g.