Energizer Ultimate Lithium AA review: the battery to leave in a go-bag for years and trust in a winter outage

This is a research-based review, based on manufacturer specs and published data. We do not test products. Specs come from Energizer's Ultimate Lithium batteries page, checked November 1, 2026. Safety and planning guidance come from the CDC and Ready.gov.

Every outage kit has a battery problem. Rechargeables need charging. Alkaline cells lose charge over the years and can leak inside a flashlight you have not opened since the last storm. And winter outages expose batteries to cold that cuts their output.

Energizer's Ultimate Lithium AA is built for exactly those weak points. Energizer rates it for up to 25 years in storage, operation from -40°F to 140°F and leak-resistant construction, and calls it its longest-lasting AA. The catch is that each cell is single use.

Who should buy it

• Anyone stocking a go-bag or car kit that might sit for years between uses.
• Households in cold climates, where batteries may sit in an unheated house, garage or car during a winter outage.
• People who want the spare-battery bag for flashlights and radios to be something they can forget about.
• Owners of high-drain AA gear, such as headlamps, who want long runtime from one set.

Who should skip it

• Anyone who will run AA gear every night of a long outage. A rechargeable set such as Panasonic eneloop and a USB charger cost less per hour of light.
• Safety alarms whose manuals specify alkaline. Kidde, for example, says lithium batteries should not be used in its COPD CO alarm.
• Devices whose manuals exclude lithium cells for any reason. Check before you swap.

Strengths

• Up to 25 years in storage, per Energizer, far beyond any rechargeable claim.
• Extreme temperature range. Energizer rates performance from -40°F to 140°F, which covers a winter car trunk and a summer attic.
• Leak resistance. Energizer describes leak-resistant construction and says the AA cells are 100% leak proof based on standard use.
• Long runtime. Energizer calls it the world's longest-lasting AA battery.
• Light. Energizer describes the cells as lightweight, useful in a go-bag.

Drawbacks

• Single use. Once spent, they go to battery recycling.
• Cost per hour. For gear used daily, rechargeables are cheaper over an outage.
• Not for every device. Some alarm and device manuals specify alkaline only.
• No capacity on the product page. Energizer's page gives storage, temperature and leak claims, not mAh.

How it compares

Ultimate Lithium against the rechargeable AA options. Figures are from each manufacturer's page, checked November 1, 2026.

Using it in a long outage

Split the battery stock

The best outage kits use two kinds of AA. Long-storage lithium cells go where batteries wait for years: the go-bag, the car kit and the sealed bag of spares taped to each flashlight. Rechargeables go in the lanterns and radios you run every night once an outage starts, and you recharge them from a power bank or power station.

1. 01Put a set of Ultimate Lithium cells in every flashlight and radio in the go-bag and car.
2. 02Keep one spare set per device in its original packaging, so cells cannot short.
3. 03Write the purchase year on the package.
4. 04Use alkaline cells in any alarm or device whose manual calls for them.

Cold-weather outages

Battery output drops in the cold, and a winter outage can leave a house, garage or car well below freezing. Energizer rates these cells down to -40°F, and Panasonic rates eneloop down to -4°F. If your flashlights live in a car or an unheated mudroom, lithium is the safer choice for winter.

Ready.gov advises having flashlights for every household member and planning batteries for when the power goes out. Lithium cells make the first part reliable after years in storage. Our rechargeable batteries guide explains how to pair them with a rechargeable set, and the blackout checklist covers what else goes in the kit.