Batteries

Best rechargeable batteries

Although reviews say that Energizer e2 Lithium disposables last longer in digital cameras, experts agree that rechargeable NiMH (nickel metal hydride) batteries are much more cost-efficient in the long run. Reusable batteries are also better for the environment. They take a bit more effort since you need to recharge them periodically, but it's easy to see the cost savings. Editors at Consumer Reports say that a single NiMH rechargeable AA battery can last roughly as long as 500 standard AA alkaline disposables or 140 disposable AA lithium batteries. NiMH batteries are now memory-free, which means that frequent charge-discharge cycles won't degrade their performance or life span.

In tests, most reviewers found few differences in performance among NiMH batteries of the same power output. Rechargeable NiMH batteries come in several power ratings, from about 1,700 mAh to 2,700 mAh; tests show that longevity tightly corresponds with the power rating and that the price difference is rarely more than a dollar or two per 4-pack. Reviews, therefore, say you should go for a higher power rating of 2,500 or 2,600 over 1,700 or 1,800 mAh. A higher power rating means less recharging.

The Energizer 2500 NiMH rechargeable batteries (*est. $14 per 4-pack, AA) last a bit longer than others in most tests. We also found good reviews for the Duracell 2650 NiMH rechargeable batteries (*est. $10 per 4-pack), which cost a bit less. In tests that compare the two, the lower-rated Energizer rechargeable batteries actually outperform the higher-rated Duracell NiMH batteries. You can also buy the Energizer 2500 mAh batteries as a kit with a charger and four AA batteries (*est. $40) . Energizer also makes NiMH batteries in AAA, C, D and 9-volt sizes; of course, you will need a charger to keep them primed. A corresponding universal charger, the Energizer Family Charger, costs about $20 and charges all sizes (batteries not included).

The top-rated rechargeable batteries at Rechargeable-Battery-Review.com are the Maha Powerex 2700 NiMH . We didn't see them tested by many other reviewers, but the Maha batteries would be a good choice as well. This brand is a little harder to find in stores than others. Kodak Rechargeable Digital Camera 2500 mAh batteries (*est. $8 per 4-pack) don't perform as well as some competing rechargeable batteries, but they cost less and still outperform alkaline batteries.

If you don't buy your batteries with an included charger, be sure to match the type of charger to the battery. Using a higher-capacity charger for higher-capacity batteries will cut down on the length of charging time. Be sure you're getting a charger for NiMH batteries; Bill Howard of PC Magazine warns that "NiMH batteries are sensitive to overcharging and require closer monitoring by the charger; plug NiMH batteries into a charger designed for NiCds and you may overcharge and damage them." NiMH chargers will automatically shut down or provide only a trickle charge when they sense the batteries are fully charged.

Experts are mixed on whether rapid chargers are a good idea. These claim to recharge a 4-pack of NiMH batteries in only 15 minutes. However, experts caution that the batteries are only charged to about 80 percent capacity at that point. It would take another hour or two to reach fully charged status. Rapid chargers can also be harder on batteries and reduce their lifespan.

Best disposable batteries

There are some situations where a disposable battery is preferable to rechargeable batteries. Since NiMH batteries lose their charge even when they are not being used (about 1 percent for each day they are idle), they are not the best choice for low-drain items such as remote controls or flashlights. You should not, for example, use a rechargeable NiMH battery in a smoke detector or carbon monoxide detector. Alkaline batteries and nickel oxy-hydroxide cells (like Panasonic Oxyride and Duracell Power Pix batteries) do not lose their charge when they are not being used, and they can last for years in storage (about 7 years for alkaline and 10 years for lithium).

Some alkaline batteries claim to last longer than others, but in tests, these types of claims don't hold up. Standard alkaline batteries whose names include "long-life", "Xtra power" or "high performance" aren't shown to last any longer than batteries not making such claims. In high-drain electronics like portable music players and digital cameras, disposable batteries just aren't very cost-effective compared to rechargeable NiMH batteries. However, all experts say it's a good idea to keep a set of disposable batteries on hand as a backup.

Both expert and consumer reviewers recommend the Energizer e2 lithium for digital cameras if you must use a disposable battery. In tests, they actually last longer than NiMH rechargeables, but in the long run, they cost a lot more.

Lithium batteries do have another advantage over other types: they perform better in low temperatures. So if you plan to take your camera camping in extreme weather, lithium batteries may perform better than rechargeable or alkaline batteries. For most other uses, though, rechargeable batteries are still more economical.

We did find one reviewer who notes a drawback to the Energizer e2 Lithium batteries when used in digital cameras. Troy Dreier of PC Magazine notes that the e2 batteries have a power output of 1.3 volts compared to 1.5 volts for typical alkaline batteries, a difference that Dreier says can affect refresh rate in your camera (and determines how quickly you can squeeze off another shot).

However, according to the more detailed information we found at StarBatteries.com, alkaline batteries only maintain their 1.5-volt power when they are fresh (this is why a flashlight is initially brighter with fresh alkaline batteries). They decline down to about .7 volts, and average about 1.2 volts over their lifetime. Meanwhile, NiMH batteries output about 1.2 volts for 80 percent of their charge cycle. So among the types of batteries, there isn't a large difference in voltage. If you notice that your camera is taking longer from shot to shot, you might try switching types.

Among standard alkaline batteries, experts say Duracell CopperTop batteries (*est. $3.50 per 4-pack, AA) sometimes last longer than others. Duracell batteries may run your child's toy a little longer, but if they cost twice as much as an off-brand, your energy costs could be high. Most reviews didn't find there to be a huge difference from brand to brand, though most recommend sticking with name brands or store brands rather than knockoffs.

In tests, reviewers found Kirkland Signature batteries from Costco (*est. $10 for a 48-pack) and Rite-Aid AA batteries (*est. $3.50 for a 4-pack) to perform about as well as standard alkaline batteries from Duracell or Energizer. Tony Dreier at PC Magazine says IKEA alkalines (*est. $3 for a 10-pack) are just fine. In the case of standard alkaline batteries, consider simply buying by price.

So-called "heavy duty" nonrechargeable batteries, also recognized as carbon zinc or zinc chloride batteries, are not the same as alkaline batteries. Generally used in low-drain consumer electronics, heavy duty batteries are configured in the most common sizes (AA, AAA, C, D, 9V), as well as specialty sizes. These batteries typically do not last as long as alkalines, but they are less expensive and might be suitable for seldom-used, low-drain devices.

If a carbon zinc or zinc chloride battery is discharged too far, corrosion of the cathode, which is the zinc shell, can occur and the batteries can leak. This is a common cause of damage to battery-powered appliances which are left unattended for long periods with batteries inside. The electrolyte leak can also cause minor skin damage and requires careful handling.

Important Features: Batteries

• Rechargeable batteries are better in the long run. Aside from a huge cost savings over disposable batteries, rechargeable NiMH batteries are better for the environment since you can reuse them so many times.

• Rechargeable batteries lose their charge over time, even if they are not being used. For this reason, do not use them in devices that sit idle such as flashlights or remote controls.

• Make sure battery chargers are "intelligent." These shut themselves off when the battery is fully charged.

• Don't mix partly used and new batteries in the same device. The new batteries treat the old ones as part of the load and will try to recharge them, making them heat up and leak.

• Store batteries in a cool, dry place. In storage, alkaline batteries are good for about 7 years. Lithium disposables are good for about 10 years. High temperatures, low temperatures and humidity can shorten a battery's life.

• Keep a few disposable batteries on hand in case your rechargeable batteries run out at an inconvenient time.

• Don't carry loose batteries in your purse or pocket. If a battery inadvertently comes into contact with a metal object such as coins or keys, the battery may charge, leak or in rare incidences even rupture.

Our Consensus Report shows how many times products are top-ranked by reviewers included in our
All The Reviews Reviewed chart.

# of Picks	Model (with Retailer Links)	Details from Amazon.com
6	Energizer e2 Lithium disposable (*est. $12 per 4-pack, AA)	details
3	Panasonic Oxyride (*est. $5 per 4-pack, AA)	details
3	Energizer 2500 mAh (*est. $14 per 4-pack, AA)	details
2	Duracell CopperTop alkaline (*est. $3.50 per 4-pack, AA)	details
2	Duracell 2650 mAh (*est. $16 per 8-pack)	-
1 each	Energizer Ultimate, Kirkland (Costco), Kodak Digital Camera 2500 mAh NiMH , Fujifilm 2500 mAh NiMH, Maha Powerex 2700 mAh NiMH , Sanyo 2700 mAh NiMH , Ansmann 2700 mAh NiMH

In most applications, alternatives to alkaline batteries are a better choice. For digital camera batteries, several recent comparison tests from experts give the edge to disposable Energizer e2 Lithium batteries by a wide margin. However, experts agree that, in the long run, rechargeable NiMH batteries are much less expensive for high-drain electronics.

For low-drain items, disposable batteries such as the Panasonic Oxyride and Energizer e2 are better options, since they don't lose power when not in use. Standard alkaline batteries are inexpensive, and they have a long shelf life; some reviews recommend buying by price when it comes to alkaline batteries.

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