Best rechargeable batteries
Battery experts recommend rechargeable Nickel-Metal Hydride (NiMH) batteries for most purposes. Since they can be recharged at least 500 times before needing to be recycled, they’re better for the environment and are more cost-effective. The problem has been that NiMH rechargeable batteries don’t hold their charge very long in storage – they lose about one percent of their stored energy every day. One percent a day doesn’t sound like much, but it’s like compounding money in the wrong direction. After a month, capacity drops to about 73 percent; by three months it’s only 40 percent, by six months 14 percent. Keeping them charged can get tedious, and owners complain that it’s inconvenient to have to recharge NiMH batteries right before using them.
Two competing solutions emerged to solve this problem, but only one has survived. Rayovac has discontinued its popular IC3 batteries (*Est. $10 for four AAs) that recharged in just 15 minutes in favor of hybrid rechargeable batteries that keep their charge much longer. However, comparison tests show that two other brands of hybrid batteries perform better. Sanyo eneloop (*Est. $10 per four-pack, AA) leads the pack, with UniRoss Hybrio (*Est. $15 for four AAs) close behind. They both can be recharged up to 1,000 times.
Also called “low self-discharge rechargeable batteries,” these batteries combine the benefits of rechargeable batteries with those of alkaline batteries – hence the popular term “hybrid batteries.” They self-discharge at such a slow rate that after a year, they still have about 85 percent of their capacity. They’re also called “pre-charged” batteries, because they’re charged up to that capacity right at the factory. That means you can use them right out of the package, or store them for future use.
Unlike the Rayovac IC3 15-minute batteries, hybrid batteries can be recharged in any good-quality battery charger. (Experts say it’s well worth buying a good “smart” charger to protect your investment in rechargeable batteries.) Sanyo eneloop batteries come in AA and AAA sizes, but you can also get adapters to use them in devices that use C or D batteries. The Sanyo eneloop Power Pack (*Est. $35) includes a charger, eight AA batteries, four AAA batteries and two each of the C and D adapters. All these components are also available individually. Tests find that these eneloop batteries actually do last much longer than older rechargeable batteries, and we found numerous blog entries dedicated solely to recommending these batteries.
USB battery chargers are also popular with frequent computer users, and with travelers who don’t want to take separate chargers for all their electronic devices. By recharging AA and AAA batteries via a USB port on a laptop computer, only the laptop’s cord is needed. Sanyo makes a USB charger kit (*est. $15) that comes with two AA eneloop batteries. This is so popular that it’s gotten rave reviews from over 350 owners at Amazon.com.
There’s been some buzz about regular NiMH batteries that have a USB connector built right into their cap. USBCell batteries (*Est. $20 for two AAs) don’t hold their charge a long time the way Sanyo eneloop or UniRoss Hybrio hybrid batteries do, yet they cost more. However, you don’t need an extra charger, so if you only need two AA batteries and have USB ports free on your computer, they can be a good buy.
Best rechargeable batteries for digital cameras
In addition to voltage, batteries are rated in milliAmpere-hours (mAh) – thousandths of amp-hours. So a 2,700mAh battery is equivalent to a 2.7Ah battery. Although the Sanyo eneloop and UniRoss Hybrio batteries discussed above are recommended for digital cameras as well as other devices, they’re only rated at 2,000mAh. There are regular NiMH rechargeable batteries available with capacities up to 2,700mAh for longer runtimes per charge. These high-capacity rechargeable batteries are a good choice for powering digital cameras in situations where flash will be used a lot.
Energizer 2500mAh batteries (*Est. $12 for four AA) are high-capacity rechargeable batteries that earn excellent reviews. They don’t hold their charge as long as hybrid batteries, but their higher mAh rating means they’ll last longer in a fast-draining device like a digital camera. They come in 9-volt, C and D sizes as well as AA and AAA, and all these sizes can be recharged in a universal charger such as the Energizer Overnight NiMH Family Battery Charger (*est. $23).
If you don’t mind having to charge these batteries shortly before each use, reviews say they’re a good choice for fast-draining devices such as a digital camera or radio. For anything that uses battery power more slowly or intermittently — like a remote control or flashlight — a hybrid battery is much better. Hybrid batteries are also better, of course, for anything used infrequently.
Comparison tests show that the Energizer 2500 batteries outperform the Duracell 2650 NiMH batteries (*Est. $15 for four AAs) – but the difference in performance isn’t enough to justify the higher price. These Duracell rechargeable batteries are only available in AA and AAA sizes, but that’s the size most fast-draining devices use anyway. The Duracell CEF90NC kit (*est. $20) includes a 30-minute charger plus four AA batteries. A 15-minute charger is also available, but battery experts suggest that quick chargers shorten battery life and cost more. Chargers that take two to five hours are the most cost-effective solution.
Maha Powerex 2700 NiMH (*Est. $13 for four AAs) batteries earn first rank in comparison tests at Rechargeable-Battery-Review.com, and earned a 2004 Editors’ Choice award at PC Photo magazine. They now carry a five-year warranty. Maha chargers also get top ranking at Steve’s Digicams. The Maha MH-C204F (*est. $20) charges both AA and AAA batteries, and the Maha MH-C204F-DC (*est. $23) includes adapters for both AC and 12-volt DC outlets.
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 NiCads 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 four-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
Disposable batteries cost more in the long run, both for the user and for the environment, considering the environmental costs of making them and disposing of them. Until recently, reviews recommended disposable batteries for low-drain items such as remote controls or flashlights, since regular NiMH rechargeable batteries lose their charge even when not being used. Hybrid batteries solve this problem. For long trips, reviews often recommend disposable lithium batteries because of their long runtime. However, hybrid batteries plus a USB or solar charger take care of travel needs well too.
Alkaline disposable batteries are still cost-effective for smoke detectors and similar devices where replacement isn’t needed often. Reviews say that price is the main thing to look for in alkaline batteries for this purpose. Small differences in performance and runtime are quickly overshadowed by differences in price. Since alkaline batteries keep their charge well in storage, it’s safe to stock up when you find a good sale.
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. Among standard alkaline batteries, experts say Duracell CopperTop batteries (*Est. $5.50 per AA four-pack) sometimes last longer than others. In tests, reviewers also found Kirkland Signature batteries from Costco (*est. $10 for a 48-pack) and Rite-Aid AA batteries (*est. $3.50 for a four-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 ten-pack) are just fine.
If there’s some reason you must use disposable batteries in a digital camera, however, then performance and runtime matter more – especially for fast shots or shots using flash. Reviews recommend Panasonic Oxyride (*Est. $12 for four AAs) batteries for their longer runtime. Made with oxyhydroxide, fresh Oxyride batteries provide 1.7 volts compared with 1.5 volts for regular alkaline batteries. David Pogue’s comparison tests for The New York Times show that regular alkaline batteries last longer in a device that’s on continuously, but Oxyride batteries have significantly longer runtime if the device is used intermittently. If you take a few shots with your camera and then turn it off, for example, the Oxyride batteries will last longer.
However, based on many comparison tests, reviews agree that for long runtime in a digital camera, Energizer e2 Lithium ( *Est. $12 per four-pack, AA) are the most cost-effective disposable batteries. Even though they cost more than alkaline batteries, they can take so many more photos that each photo costs much less to shoot. Recovery time between shots is generally good, and it’s more convenient to change batteries less often.
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.
Hybrid batteries plus a solar charger are a good bet for disaster preparation kits. However, disasters often bring stormy weather that can make solar charging problematic. Since lithium batteries keep their charge for ten years, they’re a good addition to a disaster kit. Lithium batteries also weigh about 30 percent less, so they’re ideal for travel cameras and flashlights. Some of the best such flashlights use the tiny cylindrical C123A lithium batteries. Many brands of C123A are expensive, but at FlashlightReviews.com, an enthusiast site, reviewer Doug Pribis recommends Titanium Innovations CR123A (*est. $1 each) found online. He also recommends Pila 600S rechargeable lithium-ion batteries (*est. $36 for four), which work with most (but not all) flashlights that use C123A batteries.
So-called “heavy duty” non-rechargeable batteries, also recognized as carbon zinc or zinc chloride batteries, are not the same as alkaline batteries. According to the Technical FAQs on RayovacDirect.com, “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. They are difficult to find, however.
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.