Buying Guides: Batteries

If you take a quick look around your house, you're bound to find a large number of items that run on battery power. Remote controls, flashlights, cordless tools, clock radios, smoke detectors and more all draw their energy from batteries. Putting a little thought into which batteries you purchase can have the double benefit of saving you money and increasing the run time of the object you're putting the batteries into. Keep the following questions in mind as you shop for new batteries:

• Are you looking for disposable or rechargeable batteries?
• What's the best way to store batteries?
• How long will different types of batteries last?
• How can you properly dispose of batteries?
• Will all chargers work with all batteries?

Types, Storage and Disposal

Batteries come in all shapes and sizes, ranging from tiny little watch batteries to enormous car batteries. Manufacturers make claims about how long their batteries will last and how powerful they are, but more important than picking a brand in most cases is selecting the right type of battery, be it alkaline, lithium or nickel metal hydride. It's also important to realize that different items use battery power at different rates. Laptop computers and digital cameras, for example, drain batteries at a much faster rate than an alarm clock or smoke detector. This means that even though two different items might require the same size battery, it may not be best to use the same type of battery in each. If you purchase extra batteries to have on hand when your old ones run out, make sure you store them properly to extend their shelf life. Remember that while some old batteries can simply be tossed out in the garbage, others will need to be recycled.

Disposable Batteries: Disposable, or primary, batteries come fully charged and ready for use. Once their power has been drained, they are discarded. Disposable batteries are economical to purchase and hold their charge for long periods of time when not in use, making them ideal for everything from toys and radios to flashlights and smoke detectors. The three most commonly found types of disposable battery are alkaline, lithium and carbon zinc, or "heavy duty." They self-discharge at extremely low rates, making them ideal for tucking away in a drawer for emergency use at a later date. While they can be used for high-drain devices like digital cameras, disposable batteries provide greater economy in devices that require a little less power or are used less frequently.

• Shelf life for disposable batteries may be five years or longer
• Never try to recharge disposable batteries, as it may cause them to rupture or leak
• "Heavy-duty" batteries are best suited for low-drain devices
• Ideal for a combination of medium-drain and low-drain devices, including toys, non-digital cameras, clocks and alarms

Rechargeable Batteries: Rechargeable batteries can be charged hundreds of times, supplying power for years before needing to be replaced. Though they generally have a higher up-front cost and require the purchase of a charger, rechargeable batteries are often a more economical option in the long run. They are well suited for frequently used, heavy-drain devices, including everything from digital cameras and cell phones to laptop computers and cordless power tools. The most frequently used types of rechargeable batteries are nickel metal hydride (NiMH), nickel cadmium (NiCad) and lithium ion.

• Rechargeable batteries have a limited shelf life and higher rates of self-discharge than primary batteries
• Rechargeable batteries may self-discharge nearly half their power within a month
• Ideal for high-drain applications, such as cell phones and portable music players
• Fully charged batteries that sit unused for long periods of time may need to be recharged before use

Type	Benefits and Points to Consider	Uses
Alkaline	May be used in many devices May have a shelf life of 5 years or more Lower initial cost Suitable for both high- and low-drain devices May be disposable or rechargeable Rechargeable alkaline batteries have shorter run times than other types	Calculators Cameras Clocks Flashlights Games and toys Pagers Radios and stereos Remote controls Smoke detectors
Carbon Zinc	Generally have the lowest initial cost Disposable Tend to have shorter run times Best suited for low-drain devices	Clocks Remote controls Smoke detectors
Lithium	Well suited for high-drain devices Disposable Lighter than alkaline batteries May have a shelf life of 10 years or more Perform well at low temperatures	Cell phone backup power Digital cameras Halogen- and krypton-bulb flashlights Motorized toys Portable TVs and music players
Lithium Ion	Rechargeable Longer shelf life than other rechargeable batteries More expensive Provide higher energy capacity Require more sophisticated chargers May be more sensitive to overcharging Very lightweight	Camcorders Cell phones Digital cameras Laptop computers Portable power tools Portable televisions
NiCad	Rechargeable Must be properly recycled May have a slightly lower capacity Limited shelf life Better for infrequently used items Work best when completely discharged prior to being recharged	Camcorders Cell phones Electric razors Laptop computers
NiMH	Highly cost efficient Ideal for frequently used, heavy-drain devices Perform well at low temperatures Interchangeable with disposable batteries of the same size AC-power dependent Limited shelf life Rechargeable Require more sophisticated chargers Higher purchase price More environmentally friendly	Camcorders Cell phones Cordless tools and appliances Digital cameras and flash equipment Laptop computers Motorized remote control toys Portable power tools

Storage, Usage and Disposal: Even if they're sitting on a shelf in their original packaging, all batteries will gradually lose their charge over time. Excessive heat or cold may speed up this process, so it's important to store batteries at room temperature. When the time comes to replace batteries, replace all of them at the same time, even if you think some of them may have some juice left. If you mix old and new batteries, the old batteries will be under increased strain, which may cause them to leak or rupture. You should also avoid keeping loose batteries mixed in with coins, paper clips or other metal objects, as the batteries may short-circuit and heat up. Removing batteries from objects that you don't intend to use for a long period of time can help preserve their charge. Every device drains batteries at a different rate, and while there are negligible differences between the run times of most batteries of equal size and power, one manufacturer's batteries may work better than another in a given device. Try different brands and keep track of the run time to see which ones work best in the devices you use most frequently.

• Always make sure the positive (+) and negative (-) ends are properly aligned
• Use only the size and type of batteries specified by the manufacturer of a device
• Use a pencil eraser or cloth to keep contacts in battery compartments clean
• Avoid mixing and matching batteries from different manufacturers in the same device
• Do not put batteries in fire, as they may explode
• Make sure battery-powered devices are off when not in use to conserve power
• Alkaline batteries can be safely disposed of along with household waste
• NiCad and batteries containing lead must be properly recycled, as they can present environmental hazards
• Please recycle your old batteries by bringing them to a local battery recycling drop-off
• Bring your old power tool batteries into your local The Home Depot for recycling

Features

Specialty Batteries: In addition to standard-size batteries, such as AA, C and D, there are a number of batteries designed for very specific purposes. Watches, cameras, hearing aids and other items have specially sized batteries intended solely for their use.

Chargers: If you purchase rechargeable batteries, you'll also need to purchase a charger. "Smart" chargers charge batteries quickly (sometimes within an hour or two) and then slow the charge to a trickle when batteries are full to avoid overcharging. Some chargers that are identified as "quick" chargers can take several hours to charge, however, so make sure you read the fine print. You'll also want to make sure that you have extra batteries on hand to use in devices while you're charging the spent batteries. Bear in mind that not all chargers work with all types of rechargeable batteries, so make sure you have the right one for the type of batteries you're using. Some items, such as power tools, come with their own chargers designed to recharge the included batteries.

Adapters and Converters: If you plan to bring along rechargeable batteries on that overseas trip, don't forget that you may need an adapter or converter to ensure proper use.