How to find the right battery for the job
Batteries supply the energy for many items in your home, from your kids' toys to your remote controls. There are two types of batteries on the market today: Rechargeable and disposable.
Rechargeable batteries are the most expensive type, costing anywhere from $15 to $31 for a pack of eight AA's. There are other technologies, for example the older nickel-cadmium (NiCd) battery, but experts say that for most effective type are nickel-metal-hydride (NiMH). All of the rechargeable batteries are NiMH.
Despite their higher initial cost, for most uses, rechargeable batteries are a good long-term value. That's because batteries of this type can be recharged and used again and again -- anywhere from 100 to 1,500 times, according to energy experts. If you pay $20 for a set of four AA batteries and a charger, and you use the batteries 500 times before they wear out, their cost per use (including the electricity used for charging) comes to around 5 cents. By contrast, four-packs of disposable alkaline batteries (profiled below) would cost you between $3 and $4 a pop.
In addition to being more cost-effective, rechargeable batteries are a greener choice. Choosing one rechargeable battery instead of 500 alkaline ones reduces the amount of waste by a factor of 500. It's also easy to recycle rechargeable batteries at the end of their life by dropping them off at locations such as Lowe's, Home Depot, and Radio Shack. Disposable batteries, by contrast, can't be recycled in most areas.
In the past, rechargeable batteries had a few major drawbacks compared to disposables. First, they tended to lose their charge over time, so batteries kept in storage often had to be recharged before use. This made them less suitable for emergencies. However, modern low self-discharge (LSD) rechargeable batteries, such as the Panasonic Eneloop, have largely eliminated this problem. These batteries retain around 75 percent of their charge after one to three years in storage.
Second, until recently, it was hard to find rechargeables in sizes other than AA and AAA. Many popular brands, such as the Eneloop and the more powerful Eneloop Pro, still come in only these sizes. However, there are now a couple of well-known brands, including the Energizer Recharge and the Powerex Imedion, that come in all standard sizes: AAA, AA, C, D, and 9-volt. The Powerex batteries aren't widely available in stores, but they're easy to find online, and the Energizer batteries are sold at several major retail chains.
However, disposable batteries have a few advantages of their own. While new technologies have greatly improved the shelf life of rechargeable cells, it still pales compared to the shelf life of disposables, which can last 10 to 15 years, depending on the type. Disposables also store more energy than rechargables, meaning that a battery will still be powering a device after a rechargeable has made several -- or many -- trips back to its charger.
The cheapest and the most widely available disposable is the old-fashioned alkaline battery. Made by familiar brands like Duracell, Energizer, and Rayovac, these typically cost around $6 for a pack of eight AA batteries, the most common size. However, alkaline batteries do best with devices with relatively low current draws; think remote control or flashlight rather than a digital camera.
Lithium batteries, like alkaline batteries, are disposable. However, they hold more energy than alkaline batteries and can withstand higher current draws. In one expert test, a typical lithium battery lasted about 50 percent longer than a typical alkaline battery at a low current drain of 200 milliamps (mA), which is about the amount used by a child's toy or a flashlight. At a higher current draw of 1,000 mA, comparable to a digital camera, the difference was even more dramatic: The lithium batteries lasted nearly three times as long as the average alkaline.
Lithium batteries are also lighter in weight than alkalines, and they function better at extremely low temperatures -- both useful qualities for winter camping and hiking. In addition, they have a longer shelf life. While alkaline batteries last 5 to 10 years, in storage, lithium batteries can last 10 to 15 years, making them useful for emergencies. That's because they don't "self-discharge," or consume their own power, as fast as an alkaline battery.
The downside to lithium batteries is their higher cost: around $13 for a pack of eight AA's. This means that for low-drain devices, the old-fashioned alkaline actually gives you a lot more bang for your buck. A lithium battery will last about 50 percent longer, but it'll cost twice as much. The exception is devices with very low power use, such as smoke detectors. In these, the lithium batteries have an advantage because of their lower self-discharge rate. Many users say they've been able to keep smoke alarms going for ten years or more on a single lithium battery. And for high-drain devices, lithium batteries not only provide a better value but also save you the trouble of toting around extra batteries wherever you go.
Finding the best batteries
To find the best batteries, we considered two main factors: performance and longevity. Performance includes battery capacity, how long batteries last in storage and, for rechargeable batteries, how long it takes to charge them. Longevity, for alkaline and lithium batteries, is simply a question of how much power they can deliver before running down. For rechargeable batteries, longevity also includes service life, or the number of times they can be recharged. Information about both performance and longevity can be found in professional battery tests conducted by consumer magazines and online publications. User reviews from Amazon.com helped us find information about specific problems with batteries, such as which brands are most likely to leak.
Best Disposable Batteries
While rechargeable batteries offer the best value for most everyday jobs, old-fashioned alkaline batteries still come in handy for emergency use. But is there really any difference among competing brands? We found conflicting information on this point. Energy expert Michael Bluejay at Michael Bluejay's Battery Guide insists that "capacity is pretty similar from one alkaline maker to the next" and cites several tests to back up his claim, but most of them are several years old. More recently, a test of batteries at Worcester Polytechnic Institute, reported at DealNews.com, found that name-brand alkaline batteries performed almost identically to generic brands and concluded that it makes most sense to buy based on price alone.
However, the most recent tests we've seen of alkaline batteries contradict these findings somewhat. Both the Battery Showdown conducted by Bitbox, a British electronics maker, and the latest battery tests at ConsumerReports.org found slight but significant differences in performance between brands. Another head-to-head test, posted by a contributor to the Instructables.com website, found still more noticeable differences. Moreover, users on Amazon.com and other sites we consulted are much happier with some battery brands than with others.
Surprisingly, the two leading battery brands, Duracell and Energizer, aren't the winners in most professional tests. Instead, the basic Rayovac Alkaline ($18 for 60 AA batteries) battery, which costs as little as 30 cents each when bought in bulk, moves to the top. For example, in the Instructables.com test, both the Duracell Coppertop (Est. $6 for 8 AA batteries) and the Energizer MAX (Est. $11 for 16 AA batteries) die faster in a flashlight than a basic Rayovac Alkaline. The budget-priced Rayovac battery isn't included in the tests at BitBox and ConsumerReports.org, but the DealNews test finds that it performs exactly as well as Duracell and Energizer and concludes that it's a much better value than either one.
In addition, users at Amazon.com are actually more satisfied with the Rayovac batteries than they are with other leading brands. Reviewers describe them as a great value, lasting every bit as long as the Energizer or Duracell. They also consistently say that these inexpensive batteries do not leak the way off-brand batteries often do. There are a few scattered complaints that the Rayovac Alkalines die quickly in high-drain devices, but that's to be expected with any alkaline battery and these complaints aren't sufficient in number to raise any concerns. At Amazon.com, the 60 pack of AA batteries draws a rating of 4.5 stars based on nearly 240 reviews, and other quantities and battery sizes score similarly, or better.
Duracell Coppertop batteries are also strong performers, but they're not quite as consistent according to reviews. In one professional test, these batteries are among the top performers, holding out longer than most other alkaline batteries in both a flashlight and a child's toy. However, a different test places them in the middle of the pack. They do very well under low-drain conditions, but, again, their performance under high drain is unimpressive. This, combined with their relatively high price, leads the testers to declare them a poor value.
User reviews of Coppertop batteries are also somewhat mixed. At Amazon.com, where we found more than 4,000 reviews for these batteries, most users are satisfied with them. Reviews generally say the batteries last a long time, and many claim they're less likely to leak than other brands. However, reviews we found on the manufacturer's website seem to contradict this point. Many users who say they used to be loyal Duracell customers complain that the newest generation of Duracells is very prone to leakage.
As for the Energizer MAX batteries, they remain popular with users. In more than 1,750 reviews on Amazon.com, about 90 percent of owners recommend these batteries for their long life – although, like the Duracells, they get some complaints about leakage. However, their performance in professional tests is unimpressive. One test finds them slightly better than Duracells for high-drain use, but in most tests, their performance is identical or slightly worse.
In general, name-brand batteries like Duracell, Energizer and Rayovac fare better in tests than cheaper generics. However, there are a couple of store-brand batteries that do surprisingly well. For instance, one consumer publication gives very high marks to the Kirkland Signature Alkaline (Est. $19 for 72 AA batteries), a store-brand battery from Costco. It performs nearly as well as the Duracell Coppertop and well ahead of the Energizer MAX, at a significantly lower price. However, user reviews for this battery in various sizes and packages are hard to find, and the ones we did locate (albeit mostly not at Costco.com, the primary retailer), were disappointing with lots of complaints about leakage.
The other surprisingly strong performer in comparison tests is the IKEA Alkalisk (Est. $2 for 10 AA). In the extensive Bitbox comparison test, the Ikea battery is "the clear winner" for both high-drain and low-drain use, delivering more power than its competitors at a very low price. However, since the IKEA website doesn't host reviews from owners, we couldn't find much user feedback to back up this result. Also, Alkalisk batteries are only sold in IKEA stores, and there are fewer than 50 such stores in the country. Still, if you happen to have one in your area, you can pick up some good batteries at a great price.
Energizer Ultimate Lithium is the best for power-hungry devices
There may be some question about whether any alkaline battery is better than any other, but there's no question at all about the difference in performance between alkaline batteries and lithium batteries. In professional tests, lithium batteries consistently outperform alkalines by a wide margin, especially in high-drain devices. In addition, lithium batteries lose charge at a much lower rate than alkaline batteries. This means they last longer in storage and in devices that draw very little current, such as smoke detectors.
In the United States, Energizer is the leading manufacturer of lithium batteries and the only brand that's covered in professional tests. Energizer sells lithium batteries under two brand names: Energizer Ultimate Lithium ($14 for 8 AA batteries) and Energizer Advanced Lithium (Est. $15 for 8 AA batteries). Energizer claims its Advanced Lithium battery lasts up to six times as long its alkaline batteries in a digital camera, and the Ultimate Lithium battery can last even longer (though it doesn't say how much longer). The Ultimate Lithium also has a longer shelf life: up to 20 years in storage, compared with the Advanced Lithium's 12 years. Both batteries come in AAA and AA cell sizes, as well as the 9-volt size required for many smoke detectors.
The Energizer Ultimate Lithium consistently trounces the competition in tests of disposable batteries. It lasts longer than any alkaline battery in both high-drain and low-drain devices, though its advantage is greatest with high-drain ones. It also beats the Energizer Advanced Lithium in the one comparison test that directly pits them against each other. The Ultimate Lithium has better reviews from users at Amazon.com, as well. In more than 2,400 reviews, owners give it 4.6 stars out of 5 overall, saying it's long-lasting, lightweight, and ideal for use in cameras. They also like its long shelf life and ability to perform at low temperatures.
The Advanced Lithium, by contrast, gets about 4.4 stars overall from roughly 900 users. Although owners praise its long shelf life, they're not as impressed with its life span as they are with the Ultimate Lithium's. Given that there's little difference in price between the two, we see no reason to choose the Advanced Lithium over the Ultimate Lithium, unless you can get a special deal on them.