History
Sanyo was acquired by Panasonic in 2009. In exchange for US FTC approval of the takeover, Panasonic agreed to sell Sanyo's portable NiMH battery business to Fujitsu subsidiary FDK in order to preserve competition, and later did so. Panasonic retained the "Eneloop" trademark, sourcing the batteries from FDK (formerly Sanyo) factories.Technology
After NIMH rechargeable batteries were introduced, they were developed to increase capacity. This was done by using thinner insulators internally, allowing more of the active components to be used and thus increasing capacity. The thin insulators allowed significant leakage, leading to relatively shortVariant description
The Eneloop is the standard general-purpose cell. The cheaper Eneloop Lite has lower capacity and a longer lifespan in charge cycles, but the standard and Lite of about the same time have very similar total lifetime capacity in watt-hours. The more expensive Eneloop Pro has significantly higher capacity and is suitable for higher-current applications, but has poorer charge retention and shorter 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 and2nd generation
The second generation of Eneloop AA and3rd 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 storage at 20°C.Eneloop Lite
1st generation
The Eneloop Lite line was released in Japan in June 2010. They addressed two disadvantages of alkaline and other NiMH batteries: the initial cost and the long charging time—both achieved by reducing the capacity of the battery. The batteries find suitable applications in low-drain devices such as remote control devices and alarms, where low capacity is not an issue. The AAs have 1,000 mAh of capacity, while the AAAs have 600 mAh. Due to reduction of the capacity compared to the regular Eneloop cells, the charging time is halved for the AA and reduced by 25% for the AAA. On the other hand, they can be recharged 3,000 times. The reduction in capacity also reduced the production cost, which decreased the initial investment for rechargeable batteries. They also weigh 30% less. The product numbers are HR-3UQ (AA) and HR-4UQ (AAA).2nd generation
Along with the upgrade of the regular Eneloop cells in April 2013, the Lite version was also upgraded. According to Panasonic, it can now be recharged up to 3,000 times (life cycles for DOD 60%) (model numbers BK-3LCC for the AA and BK-4LCC for the AAA battery). The upgraded batteries also retain 90% of the charge after one year like the regular Eneloop cells.Eneloop Pro (Eneloop XX)
The Eneloop Pro family have higher capacity in mAh, trading this off against poorer charge retention and shorter lifespan. They are better than standard Eneloops for high-drain applications. They are not recommended for applications where batteries are continuously charged, such as in DECT phones left on a charging base. Their higher self-discharge rate makes them unsuitable for very low drain applications such as clocks. Their slightly larger diameter can be problematical where the batteries are a tight fit.1st generation
The Eneloop Pro (or XX powered by Eneloop Technology in the US, Canada, and Europe) series was introduced in 2011. At that time, no AAA version was produced. They have a higher capacity than regular Eneloop cells, 2,500 mAh (min. 2,400 mAh) for AA. They retain 75% of their initial charge after one year, and can be recharged 500 times, significantly less that the standard non-Pro Eneloop line. The product numbers are HR-3UWX (AA) and HR-3UWXA (AA).2nd generation
In January 2013, Sanyo announced the second generation of Eneloop XX (model HR-3UWXB, or Panasonic BK-3HCC), branded Eneloop Pro. The new generation has a 50 mAh higher capacity (2,550 mAh nominal, 2,450 mAh minimum capacity), and the self-discharge rate was improved, retaining 85% up to one year.New Eneloop XX with Higher Capacity and Improved Low Self-Discharge3rd generation
In October 2015, Panasonic remodeled Eneloop Pro (BK-3HCD/BK-4HCD). The minimum capacity of the battery increased, by 50 mAh to 2500 mAh for AA and by 30 mAh to 930 mAh for AAA.Eneloop Plus
Eneloop Plus cells have a PTC thermistor built-in that cuts the power in case of overheating. This makes them especially suitable for toys and devices that generate significant heat. Other specifications are identical to the second-generation Eneloop batteries. The product number is HR-3UPT (AA), and the battery was released in Japan in December 2011. It was later discontinued.Counterfeit Eneloops
There are many counterfeit Eneloop batteries; in particular batteries sold onVariant comparison tables
AA size
AAA size
References
External links
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