Eneloop is a brand of 1.2-volt low self-discharge nickel–metal hydride (NiMH) rechargeable batteries and accessories developed by Sanyo (later acquired by Panasonic), introduced in 2005.
Eneloop cells lose their charge much more slowly than the 0.5–4% per day lost by older-technology NiMH batteries, retaining about 85% of their charge for a year after charging. This allows them to be sold precharged and ready for use, unlike older types.
Because they can replace a large number of alkaline batteries over their life cycle, they are marketed as being eco-friendly.
Sanyo was acquired by Panasonic in 2009. As part of that deal, the Japanese Eneloop factories were sold off to Fujitsu, which since then produces 2nd-generation eneloops under its brand. Panasonic eneloops, starting with the 3rd generation, are made in China for some markets (including Australia). As of November 2015, Eneloop Pro are still made in Japan.