Fully charges in 8 hours. Charge completely before first use. Subsequent partial charges will NOT reduce batteries' capacity through memory buildup, unlike conventional NiCD batteries. Charge either 2 or 4 batteries at a time. LED lights illuminate while charging batteries. Batteries are 100% memory free. They last up to 4x longer than regular batteries. Charges up to 1000x. They are specially engineered for High Drain Devices. NiMH technology, the number one recommended by digital camera manufacturers.