eneloop AA (8) review

Why eneloop suits an emergency kit

Ordinary rechargeable batteries lose charge sitting in a drawer; Panasonic itself says NiMH cells generally lose more when unused than disposable batteries. Eneloop's selling point is that it holds on: Panasonic says these cells retain 70% of their capacity after 10 years in storage at 68°F, compared with their minimum capacity, based on its own estimate. They are also charged at the factory, using solar power, so you can use them straight from the pack.

That is the combination a household needs for flashlights, headlamps, weather radios and lanterns: batteries that are ready when the power goes out, and that can be recharged afterward rather than thrown away.

Capacity and cycle claims, read carefully

Panasonic rates the standard eneloop AA at 2,000mAh typical and 1,900mAh minimum, at 1.2 volts, and notes capacity may vary by market. The higher-capacity eneloop pro AA is rated at 2,500mAh typical.

The box says up to 2,100 recharges. Panasonic's footnote explains that figure comes from an older 2011 version of the IEC test, and that under the updated 2017 test the count is about 600. Either way, Panasonic says capacity falls gradually with use and real life depends on how you use them. For a kit that is charged a few times a year, both numbers mean many years of service.

Using them in real devices

Eneloop cells run at about 1.2 volts against a fresh alkaline's 1.5, so Panasonic warns a device's battery gauge may show less charge than is really there. It says never to mix eneloop with disposable batteries unless the device maker allows it, and not to use them in waterproof devices such as underwater lights, because an over-discharged cell can produce gas. Panasonic recommends recharging when about 70% to 75% of capacity is used, rather than running them flat.

They are rated to work from -4°F to 122°F, so a winter outage in a cold house is within range. This eight-pack has no charger; Panasonic sells packs with one, and you will need a NiMH charger to recharge them.

Storage

Panasonic gives an ideal storage range of 50°F to 77°F and says to avoid storing them above 95°F, which raises self-discharge, and to watch for condensation when moving them from cold to warm. Its FAQ suggests recharging before use if they have sat a long time, unless it is an emergency. Keep the terminals clean with a dry cloth. A closet shelf beside the flashlights is ideal; see our power outage checklist.

How it compares, and the verdict

On our rechargeable battery comparison, eneloop pro holds more per charge, and higher-capacity cells such as the EBL AA 2800 also promise more runtime per charge. The Amazon Basics 24-pack is the low-cost bulk option. Standard eneloop is the one to buy when readiness after months in a drawer matters most.

Verdict: the dependable rechargeable for an emergency kit. Skip it if you want the most runtime per charge, have no charger and do not want to buy one, or need cells for a waterproof light.

How long do eneloop batteries hold their charge in storage?

Panasonic estimates 70% of capacity after 10 years stored at 68°F, measured against the cells' minimum capacity. Storing them cool and dry helps.

Are eneloop AA batteries really good for 2,100 charges?

That is Panasonic's figure under an older 2011 IEC test. Under the newer 2017 test, Panasonic says about 600. Capacity drops gradually either way.

Do eneloop batteries come charged?

Yes. Panasonic pre-charges them using solar energy, so they can be used straight away. Its FAQ suggests a recharge before use if they have been stored a long time, unless you need them right now.

Can I mix eneloop with alkaline batteries?

Panasonic says no, unless the device maker explicitly allows it. Use a full set of eneloop cells, charged together.