eneloop

For the technology, see Low self-discharge NiMH battery.

Eneloop AA batteries

Description

The eneloop rechargeable batteries were developed by Sanyo and introduced to the market in November 2005. They lose their charge slower than previous NiMH batteries: 10% in the first year compared to about 20% on the first day and 1-4% on every successive day. Hence the name, low self-discharge NiMH battery. eneloop batteries are sold pre-charged and can be used immediately, while regular NiMH batteries lose their charge so fast that this isn't feasible. Due to the number of alkaline batteries they can replace during their lifecycle, they're eco-friendly when used appropriately.

Batteries

eneloop

The original eneloops were introduced in AA and AAA size, with capacities of 2000mAh and 800mAh. They were rechargeable 1000 times and held their charge up to 75% for one year. Sanyo later improved them to be rechargeable 1500 times, along with switching to renewable energies for pre-charging. This revision holds 85% of the charge after one year and 75% after three years. The two revisions can be distinguished by the design of the label: They now state the minimal instead of the typical capacity, 1900mAh and 750mAh. The new revision also has a crown printed on the label. The new type numbers are HR-3UTGA (AA) and HR-4UTGA (AAA).
Sanyo introduced C and D sized eneloops with a minimal capacity of 2700mAh and 3000mAh in 2009, along with a new universal charger. As these sizes are only available in Japan, Sanyo also offers adapter sleeves to fit AA sized eneloops in devices that take C and D sized batteries.

In October 2011 the batteries were again improved to hold their charge for up to 90% after one year, 80% after 3 years and 70% after five years. In addition to the lower self discharge rate, the batteries can be recharged up to 1800 times compared to 1500 times in the previous revision. The product numbers for these batteries are HR-3UTGB (AA) and HR-4UTGB (AAA). At the same time, the C and D sized eneloops stated minimal capacity were increased to 3000mAh and 5700mAh respectively. They were available in Japan from November 2011.

eneloop lite

eneloop lites were released in Japan in June 2010. They are intended to address two other downsides of regular NiMH and alkaline batteries: the initial cost and the long charging time, both achieved by reducing the capacity of the battery. The eneloop lite AAs have 1000mAh, while the AAAs have 600mAh. Due to reduction of the capacity compared to the regular eneloops, the charging time is cut in half for the AA and to 3/4 for the AAA. On the other hand, they can be recharged 2000 times. The reduction in capacity also reduced the production cost, which decreased the initial investment for rechargeable batteries. The product numbers are HR-3UQ (AA) and HR-4UQ (AAA).

eneloop pro (XX powered by eneloop Technology)

eneloop pro (or XX powered by eneloop Technology in the US and Europe) were introduced in 2011. They have a higher capacity than regular eneloops, 2500mAh (Min 2400mAh). However, they retain only 75% of their initial charge after one year, and can only be recharged 500 times. The product number is HR-3UWX (AA).

eneloop plus

eneloop plus have a PTC thermistor built-in that cuts the power when the batteries are overheating. This makes them especially suitable for toys. Other specifications are identical to the second-generation eneloops. The product number is HR-3UPT (AA) and the battery was released in Japan in December 2011.

Accessories

eneloop mobile boosters

There are numerous chargers for eneloop, including USB chargers and eneloop-operated hand warmers, which double as chargers. Mobile power boosters are intended to recharge electronic devices via USB on the go using eneloops or built-in Lithium-ion batteries.
Sanyo also released plastic sleeves that turn AA into C and D sized batteries.
eneloopy is a dog-shaped battery tester. A LED on its nose shows the battery level by changing colors.