The SPOT device operates with Energizer 1.5V non-rechargeable size AA lithium batteries. Do not use rechargeable lithium batteries. They can be high voltage, which will damage the unit. Energizer 1.5V non-rechargeable size AA lithium batteries are required due to this technology's unique ability to maintain a high cell volt throughout the life of the battery. Additional benefits are a larger operating temperature range, up to 8 times longer life than alkaline, an outstanding 15-year shelf life and a 30% weight reduction.