Household charger and 4 AA batteries – $30
Travel charger with 4 AA batteries – $25
4 AA batteries – $12
+ Choice of quick or small charger
+ Desktop charger comes with AC and car adapters
+ Lifetime warranty on charger
- Short run times
- Quick charger has loud fan
- Batteries heat up during charging
Don’t ever throw the Energizer bunny away again. Instead, refresh and renew him with the company’s Rechargeable batteries. Unlike the other brands we tested, Energizer offers the choice of charging the cells with a small travel charger or quickly with a large device, but these batteries came up short on run times.
Based on nickel-metal hydride chemistry, the Energizer Rechargeable batteries come in a four-pack of AA cells with a large charger that promises 15 minute charges for $30 or a small travel charger with 4 AAs for $25. A package of four AAs costs $12.
The AA cells come pre-charged and are rated at 2,450 milli-amp hours (mah), a little short of the 2,500 mah that the PowerGenix NiZn batteries provide. After charging, they supply 1.46 volts, matching the Sanyo Eneloop cells but more than 0.3 volts short of the NiZn batteries.
I really like the 3.8-ounce travel charger, which is only slightly heavier than the Eneloop device, and can charge two or four AA or AAA cells. Don’t worry, you can’t put them in wrong—it won’t fit the wrong way.
It was able to charge two AAs in 2 hours 35 minutes, more than an hour longer than the NiZN’s charger but an hour quicker than the Eneloop’s charger. It uses a miniscule 3 watts of power, which translates into less than 5 cents of electricity a year for weekly recharges. LEDs blink furiously while charging, and the lights go solid when the batteries are ready.
If you’re in a hurry – and who isn’t these days – there’s also a quick charger that boasts 15 minutes to a fresh set of batteries. It isn’t actually as fast as it claims. We charged up a set of AA batteries in 22 minutes. But worse, it has a loud fan and used 48 watts of power during the charge cycle. It costs less than 10 cents a year to charge a set of batteries every week on this fast charger, but be careful--the batteries come out of the charger quite hot.
Energizer says that the Reghargeables can be recycled hundreds of times, which falls short of NiZN’s 1,000 cycle life. The Energizer bunny also let me down when it came to running my gear, with the shortest run times on both the flashlight (1 hour and 53 minutes) and the CD player (4 hours and 32 minutes). This is between one-half and one-third the longevity of a Duracell disposable battery, but still a good way to be green.
A bonus: the charger comes with a lifetime warranty for the original owner, meaning you’ll never have to buy another, which saves and the environment at the same time.