Hyperion Motorola Photon 4G 3500mAh Extended Battery + Back Cover Capacity: 3500mAh / 3.7V Adds minimal amount of thickness and comes with a black replacement door to accommodate the larger size of the battery. Keeps your phone charged and ready to go, even with heavy phone and data usage. Made from the highest quality "A" Grade Lithium Polymer cells. To obtain the full capacity of your battery, leave the battery/your phone on the charger for an additional 2-3 hours after the charging indicator turns green or the battery status shows full.