Batteries: Ratings of Sources
Testers at TheWirecutter.com put eight types of rechargeable AA batteries through (ahem) a battery of tests. They spend nearly 100 hours measuring capacity with a battery analyzer and testing batteries in flashlights and in a high-drain camera flash. They also charge up four batteries from each brand and set them aside for four months to evaluate their shelf life. Most recently, they update their review with feedback following six months of use. They name one favorite battery and one runner-up, but most other brands also perform well.
Choice, an Australian equivalent of ConsumerReports.org, has the best test of rechargeable batteries we've seen. Editors put 12 NiMH batteries through 200 cycles of charging and discharging and measure their life cycle, time to discharge, and how fast they lose their charge in storage. In a separate test of 25 disposable batteries, editors measure performance and endurance under high-drain and low-drain conditions. Most of the batteries in both tests are not available in the U.S.
ConsumerReports.org's editors test 13 brands of alkaline AA batteries and two brands of lithium AA batteries, measuring how long each one lasts in a toy and in a flashlight. Lithium batteries outlast most alkalines, but they cost around twice as much. The editors recommend lithium batteries for high-drain devices and alkalines for low-drain ones. Rechargeable batteries and sizes other than AA are not tested.
BitBox Ltd., a British electronics company, tests over 50 brands of disposable AA batteries. Using a specially constructed rig that drains the batteries at a steady rate, they test each battery under high and low current. Lithium batteries perform the best overall, but they cost more per ampere-hour than alkalines. Among alkaline batteries, well-known brands like Energizer and Duracell fare no better than store brands from Costco and Ikea.
Michael Bluejay is an energy expert who has been interviewed in Newsweek and on NPR. His comprehensive guide to batteries names the best types for a wide variety of uses, from smoke detectors to cameras. Bluejay recommends low self-discharge (LSD) rechargeable batteries for most purposes. Based on his research, his favorite AA rechargeable battery is the Powerex Imedion, which combines high capacity, lots of charge cycles, and a long shelf life.
Electronics enthusiast Stefan Vorkoetter tests 13 brands of LSD rechargeable batteries to see how well they hold their charge during storage. He measures each battery's power right out of the package, after a full charge, one week after charging, and seven weeks after charging. Panasonic Eneloop Pro batteries (formerly Eneloop XX) deliver the most power at every stage, followed by Energizer Recharge and Powerex Imedion. He doesn't test the batteries' performance during actual use, however.
A team of students at Worcester Polytechnic Institute tests a variety of AA batteries for DealNews.com. Testers measure each battery's initial voltage, use it for 19 straight hours, and then check to see how much voltage remains. All the alkaline batteries, from Duracell and Energizer to cheap generics, perform pretty much the same. Energizer Advanced Lithium batteries retain much more power, but they're also pricier, and their high initial voltage could damage sensitive devices.
Darren Murph, a tech reporter at Engadget.com, pits three rechargeable batteries against each other in a head-to-head test. Each battery is tested in a Nikon SB-600 external camera flash, a Wiimote (Wii remote control), and a wireless keyboard. Murph finds that all three batteries are virtually identical in both performance and price, though the Sanyo (now Panasonic) Eneloop has the edge in claimed lifespan. One of the three batteries is no longer available.
You can find just about any type and brand of batteries at Amazon.com. In fact, there are so many brands here, in so many sizes and quantities, that it's difficult to compare them. To simplify our search, we looked only at AA batteries that had high overall ratings. We found five rechargeable batteries, and six single-use ones, that had overall ratings of at least 4.5 stars from 1,500 users or more.
An Instructables.com user who goes by the name "DIYnosaur" sets up an at-home test of four alkaline batteries. Four flashlights are set up, each powered by a different battery, and observed to see how fast the light fades. A cheap dollar-store battery conks out first, but an inexpensive Rayovac Alkaline surprisingly outlasts Energizer and Duracell.
Rhett Allain of Wired tests two brand-name batteries, Duracell and Energizer, against a cheap dollar-store battery. He hooks each of the three up to a light bulb and runs it until it dies, measuring its current and voltage throughout. He finds that the two name-brand batteries perform almost identically, while the cheap one -- a heavy-duty zinc-chloride battery, rather than an alkaline -- loses power much faster.