The ‘eneloop’ was developed on the concept of "looping energy". Since first releasing the revolutionary ‘eneloop’, a AA-sized Nickel-metal hydride rechargeable battery in November 2005, Sanyo has designed and developed various battery cells, such as AAA-size ‘eneloop’ or the recently announced C- and D-size ‘eneloop’ and ‘universal charger’ in response to popular demand. With these ‘eneloop’ battery solutions, SANYO has proposed creating a new "lifestyle that values reusing and recycling”. The ‘eneloop’ battery combines the benefits of dry cell batteries by coming pre-charged with the economic and environmental benefits of rechargeable batteries, rechargeable up to 1,000 times. Unlike many other rechargeable batteries that rapidly lose their charge over time, eneloop batteries retain 85 percent of their charge after one year of non-use.