Sanyo's Eneloop batteries are one of the better-known rechargeable batteries on the market. Experts recommend the brand frequently and their longevity - on the shelf and in use - may give them an edge over other rechargeables by Energizer and PowerGenix.
Eneloops have long lives and extensive charge cycles. The latest Eneloop batteries have up to 1,500 cycles, according to Sanyo. In tests, Eneloops have been proven to last a long time without a recharge. Sanyo claims that Eneloops can retain up to 85 percent of their charge even if you don't use them within 12 months. "Sys," a user on the Photography-on-the.Net forums, performs short-term tests on various batteries, and Eneloops end up the runaway winner when it comes to shelf life. In these tests, the batteries retained 100 percent of their charge within a period of three weeks.
Because of their low discharge rate, Sanyo Eneloops can be sold pre-charged so that you can use them right out of the box. Prior to Eneloops, there were no nickel-metal hydride (NiMH) rechargeable batteries with a low self-discharge rate.
Effectively powers both high-drain and low-drain devices. TomsGuide.com's Brian Nadel tested a number of different batteries, including Eneloop cells that ran a CD player continuously for 13 hours and 35 minutes and powered a flashlight for four hours and 45 minutes. Engadget.com's Darren Murph also tested a number of batteries and found that Sanyo Eneloops can take up to 350 flash shots with a camera. Additionally, as of the review date, his wireless keyboard had been running for three months on a single charge.
However, Eneloops may take a while to recharge to their full capacity. That's one of the two problems Amazon.com reviewer "NLee the Engineer" has with the Sanyo Eneloops' bundled charger. His other complaint is that the charger only works when there are at least two batteries plugged in -- you can't charge a single cell. Test results vary. While "NLee" says that it takes up to seven hours to fully recharge an Eneloop, it only takes four hours and 45 minutes for Brian Nadel at TomsGuide.com.
Review Credibility: Excellent Darren Murph pitts the three rechargeable battery brands against each other by testing them using a Nikon SB-600 flash unit, since many rechargeables can't power high-drain devices for an extended period of time. He tests the PowerGenix batteries on the WiiMote, and they last four to six times longer than their non-rechargeable counterparts. The Eneloops were also used on a wireless keyboard and withstood regular use for three straight months.
Review: AA Rechargeable Battery Shootout: Energizer, PowerGenix and Sanyo Eneloop, Darren Murph, May 12, 2010
Review Credibility: Excellent Brian Nadel tests four different batteries by using them on a flashlight and a CD player. He monitors results by connecting the batteries' terminals to a voltmeter and using a stopwatch to monitor recharge times. All four batteries in the test are rechargeables.
Review: Rechargeable Batteries Test, Brian Nadel, March 22, 2010
Review Credibility: Excellent Stefan Vorkoetter uses a homemade computer-controlled battery manager to test the Sanyo Eneloop cells. By doing so, he is able to determine the batteries' out-of-box capacity, available capacity, self-discharge rate and charging times. He also compares the Eneloops with traditional NiMH rechargeable batteries.
Review: Review: Testing Sanyo's Eneloop Low Self-Discharge Rechargeable Battery, Stefan Vorkoetter, Not dated
Review Credibility: Very Good Sanyo's Eneloop batteries are very popular with Amazon.com customers. With more than 1,900 reviews, the rechargeable batteries earn an overall rating of 4.6 out of 5 stars. Over 1,700 owners rate the Eneloop at least 4 or 5 stars. Among those who give it a low rating, a handful received the wrong version of the battery from Amazon.com, while some received bum units that would not charge.
Review: Eneloop Pre-Charged Rechargeable Batteries, Contributors to Amazon.com, As of February 2013
5. Choice magazine
Review Credibility: Very Good Denis Gallagher compares 15 different batteries, both rechargeables and disposables. Five of the batteries, including the Eneloops, are pre-charged cells ready to use right out of the box. The batteries are tested by putting them through a continuous cycle of charge and discharge.
Review: Rechargeable AA Battery Reviews, Denis Gallagher, Nov. 21, 2012
Review Credibility: Good Forum member "Sys" posts results of his extensive testing of nine different rechargeable batteries. He tested all the batteries using an old Canon Speedlite 300EZ flash unit. Sanyo Eneloops come out on top.
Review: 6,560 Flash Pops Later: The Results of "AA" Rechargeable Battery Tests, "Sys", April 12, 2009
Review Credibility: Good Editors at CPFReviews.com test a set of Sanyo Eneloop cells by using a computerized battery analyzer. All the batteries undergo a series of charge-discharge cycles.
Review: Sanyo Eneloop Batteries Power Pack, Editors of CPFReviews.com, Sept. 1, 2009