lifespan in charge cycles; total lifetime capacity in watt-hours is much less than the other versions. Numerical data are listed in the variant comparison tables section. The discontinued Eneloop Plus was similar to the standard Eneloop, with overheating protection. Eneloop 1st generation The original Eneloop batteries were introduced in AA and AAA size, with capacities of 2,000 mAh and 800 mAh. They could be recharged 1,000 times and held up to 75% of their charge after one year. The part numbers for first generation cells are HR-3UTG (AA) and HR-4UTG (AAA). 2nd generation The second generation of Eneloop AA and AAA batteries was introduced in 2010. It endured 1,500 recharge cycles for depth of discharge (DOD) 60% and held 85% of the charge after one year and 75% after three years. The part numbers for second generation cells are HR-3UTGA (AA) and HR-4UTGA (AAA). Sanyo introduced C- and D-sized Eneloop batteries with a minimum capacity of 2,700 mAh and 3,000 mAh respectively in 2009, along with a new universal charger. As these sizes were only available in Japan and Singapore, Sanyo offered adapter sleeves to fit AA batteries in devices that take C or D batteries. 3rd generation In October 2011 the batteries were again improved to retain up to 90% of their capacity after one year, 80% after three years and 70% after five years. The batteries can be recharged up to 1,800 times, rather than the 1,500 times of the previous revision. The part numbers for third generation cells are HR-3UTGB (AA) and HR-4UTGB (AAA). At the same time, the C- and D-sized Eneloop batteries' stated minimum capacities were increased to 3,000 mAh and 5,700 mAh respectively. They were available in Japan from November 2011. European models went on sale from the beginning of October 2012. 4th generation Following the acquisition of Sanyo by Panasonic, a fourth generation was introduced in April 2013. The number of charges per cell was increased from 1800 to 2100 cycles for both AA (BK-3MCC) and AAA (BK-4MCC) models. In some countries the batteries are branded as Panasonic. 5th generation A fifth generation was introduced in 2022 (manufactured from at least April 2021). The minimum (guaranteed) capacity was increased from 1900 to 2000 mAh for AA (BK-3MCDx) and from 750 to 800 mAh for AAA (BK-4MCDx) models. These batteries are supposed to hold up to 70% of their charge after 10 years of