We live in a battery-powered world, yet little is written about those little round tubes filled with lead. There’s a big difference in batteries, and I’m going to take some of the mystery out of them. What prompted this article is a 12-volt power pack I have for a hedge trimmer I bought 15 years ago. The power pack went dead and when I contacted Sears about a replacement, they said it was no longer available. The power pack and hedge trimmer sat in the pole barn for 10 years…it was too good to throw out.

I really wanted to use that hedge trimmer this spring because my hedges were looking rather gangly. I took the power pack apart to see what the battery looked like. It was a small rectangular battery, about 6 inches long, 2 ½ inches wide and 3 ¾ inches high, with the connectors at one end. On the tag in parentheses was (12V, 6.5Ah/20HR). I knew the 12V meant it was a 12-volt battery. However, I wasn’t sure what the other combination of numbers and letters stood for. I was determined to find a replacement battery. Not knowing much about batteries, I began to look into them.

The first place I looked was in my McMASTER-CARR Supply Company book. I love this book because it has just about everything imaginable in it when it comes to supplies and tools for manufacturing. Since I have a machinist background (for over 30 years), and once owned my own machine shop, this has become a bible for me. Not only can you buy just about anything, at the beginning of many sections, there’s an information panel explaining the differences in the items listed in that section. For instance, you can learn about batteries, transformers, bearings, plastics, nylons, steel, aluminum, and so much more! This book has a wealth of information on batteries and also lists almost every battery available. Here is what I learned from the book…

Disposable Batteries

A disposable battery’s life is determined by the chemical makeup and capacity of the battery in combination with the amount of energy required to power the device it’s used with. The most familiar of these batteries include Carbon Zinc (standard everyday batteries), Heavy Duty Carbon Zinc, Alkaline, Super Alkaline, a lesser known Air Alkaline, Lithium, and Silver-Oxide and Zinc-Air.

Carbon-Zinc Batteries

Standard carbon-zinc batteries are the cheapest, most readily available battery on the market. They come in many sizes, with the most popular being AAA, AA, C, D, 9-volt plus 6 and 12-volt lantern batteries. These batteries should only be used in low-drain, occasionally used devices. Heavy-duty carbon-zinc batteries will last longer in low-drain applications and can be used in medium-drain, occasionally used devices.

Alkaline Batteries

Alkaline batteries are the most popular and come in the same sizes as the carbon-zinc batteries, plus a button style used in calculators and watches and specialty alkaline batteries commonly used in photo, electronic and medical equipment. These should be used in medium to high-drain, often-used devices. Super Alkaline batteries last longer than standard alkaline batteries in high-drain applications. Air Alkaline batteries, though not as common, are a hybrid battery that lasts twice as long as alkaline and eight times as long as carbon-zinc batteries. These are larger batteries like the 6 and 12-volt lantern style batteries. The case has tiny holes that are sealed with tape, and the battery is activated by air when the tape is removed. These batteries are commonly used in lanterns, barricade lights and telecommunications devices, because they keep voltage output at a constant level.

Lithium

Lithium (button style) batteries have a slightly higher voltage rating (3v) than Silver Oxide or Alkaline button style batteries (both 1.5v) and are used as the main power source or a back-up power source in cameras because of their long shelf life. These batteries are generally very thin, flat disks ranging in size from a dime to a quarter. They are also used in computers to power the internal clock.

Silver Oxide

Silver Oxide batteries are the familiar button style batteries used in low voltage, low-drain items like watches and calculators. These batteries can be used in place of alkaline button style batteries in most applications. The batteries are all 1.5 volts, but they come in different sizes and have different milliamp-hour ratings (see rechargeable batteries below), therefore it’s important to get the equivalent replacement, or you could run into problems with performance. When buying a replacement, there’s a listing of equivalent batteries on the back of the package, including a cross-reference to alkaline batteries when appropriate. If given the choice between alkaline and silver oxide batteries, I’ll always choose the silver oxide, because the battery will last longer.

Zinc-Air

Zinc-Air batteries are the familiar hearing aid batteries we see hanging on the pharmacy counter. While they look exactly like silver oxide batteries, they have a slightly less voltage rating (1.4V) and their chemical make-up is different, because hearing aids are a low-voltage high-drain appliance (while watches and calculators are low-voltage, low-drain). While you can use a silver oxide battery in hearing aids in an emergency, you could damage the appliance and the batteries won’t last very long.

Rechargeable Batteries

These batteries come in many shapes, sizes and voltages. Besides the standard sizes mentioned earlier (except buttons), they come in a wide array of specialty sizes suitable to the application they are used in. The most popular rechargeable batteries come in Alkaline, Nickel Cadmium (NiCad), Nickel Metal Hydride (NiMH), Lithium Ion (Li-Ion), Sealed Lead Acid, and the familiar car/motorcycle/riding lawnmower battery, which is a refillable lead acid battery. Since the car battery is so familiar, I won’t mention those (although the information on sealed lead acid batteries also applies to refillable lead acid batteries), but there’s a big difference in the others. Some batteries you can exchange (alkaline versus NiMH or NiCad) as long as the size/style and volts are the same. However, if your devise calls for a certain battery type, you best stick with that type. Also, never mix the types of batteries (like disposable and rechargeable alkaline).

Smaller rechargeable batteries (everything but the 6/12 volt sealed lead acid batteries) have a milliamp-hour rating, which is marked on the battery as a number followed by mAh or mA-hr. For example, the AA batteries I have for my camera are marked 2200mAh. When I was looking for camera batteries, I found 1050mAh, 1800mAh, 2050mAh and 2200mAh. Milliamp-hours is simply a measure of the usable hours of a battery (translated to battery life). The larger the number, the longer the battery will last. Buy the batteries with the most mAh you can find, (many are priced exactly the same) especially if you are buying standard AAA, AA, C or D batteries. They will hold a charge longer and you won’t have to recharge them as often!

If you find yourself replacing standard batteries in your electronic devises quite often, rechargeable batteries can save money in the long run. The initial expense is the batteries and the charger. More information on battery chargers is at the end of this article.

Rechargeable Alkaline

Rechargeable alkaline batteries can easily replace the standard non-rechargeable alkaline or Carbon Zinc batteries we are all familiar with (except 9v which are not available). Alkaline batteries can be charged up to 25 times, feature a longer-lasting charge, are more environmentally friendly, and are also much less expensive than nickel cadmium (NiCad) batteries. However, they have a shorter usable life expectancy than NiCad.

Nickel Cadmium (NiCad)

NiCad batteries come in AAA, AA, C, D and 9v, plus many specialty sizes used in two-way radios and cameras. These batteries are also used in power tools and portable appliances as well as in cordless phones. When you see a battery pack that looks like a bunch of batteries held together with shrink-wrap, (like those used in cordless phones) those are rechargeable NiCad battery packs. NiCad battery packs consist of individual battery cells joined together and wrapped in PVC shrink-wrap. If you were handy, you could actually make your own battery pack by using the same number and size of cells, taping them together and soldering the tabs.

NiCad batteries can be recharged hundreds of times. However, they must be completely drained before being recharged or they develop what some call a "memory", shortening the life and storage capacity of the battery. They’ve improved the performance of NiCad batteries over the years, so this isn’t as much of a problem as it used to be.

Nickel Metal Hydride (NiMH)

NiMH batteries come in AAA, AA, 9v, and specialty sizes used in cameras, camcorders, cellular and cordless phones. The big difference is battery life. These batteries can be recharged a thousand times and they don’t have to be completely drained before being recharged. This is a great asset if you are using a camcorder or camera. NiMH batteries are also more environmentally friendly than NiCad batteries. If you have a choice between NiCad or NiMH batteries for your devise, choose NiMH. The batteries will last much longer in both useable power and age.

Lithium-Ion (Li-Ion)

Li-Ion batteries are used mostly in cellular phones, and some cameras and camcorders. These batteries are lighter in weight than NiMH batteries and have longer operating times, which is useful if you are on the go a lot and can’t recharge your batteries as often.

Sealed Lead Acid, AGM

Absorbed glass material (AGM) helps immobilize the electrolyte (battery acid) in these batteries, making them leak resistant and useable in almost any position except upside down. They are housed in durable plastic, are various sizes (generally rectangular cubes) and have a variety of terminal styles and terminal locations. These batteries come in 2, 4, 6 and 12 volts, and are very versatile and powerful enough to be used for backup applications such as emergency lighting, alarm systems and uninterruptible power supplies for portable computers. The most common of these are the 6 and 12-volt lantern style batteries used as a primary power source for portable tools, lanterns, spotlights, and wildlife feeders.

The capacity of these batteries is expressed in amp-hours (AH), which is the total amount of energy available from a fully charged battery over a 20-hour period. These batteries also have a discharge rate, expressed in milliamps (mA), which simply is the constant current discharge rate for that same 20-hour period. For example, a battery with a 2.0 amp-hour (AH) capacity rating will have a 100 milliamp-hour (mA) discharge rating (it will discharge current at a constant rate of 100 mA for 20 hours).

To replace the original equipment sealed lead acid batteries, (like the one I had to replace on my trimmer) make sure the battery type, volts, amp-hours (AH), terminals and battery size match. If you can’t find an exact match, you can get away with a slightly smaller sized battery if it needs to fit in a battery compartment, and you can use a battery with a slightly larger amp-hour rating (I replaced my 6.5Ah battery with a 7Ah one), but you need to make sure you stick with the same voltage, or you could be in big trouble! As for the terminals, you can always change the connectors on the wires to match the terminals on the batteries, or simply solder the wires to the terminals, making sure that the red wire goes to the (+) terminal and the black wire goes to the (–) terminal.

Battery Chargers

You need to make sure the charger you get is for the type of battery you are charging. Placing a NiCad battery in a charger designed for a NiHM battery could cause it to explode. So, when you choose your batteries, choose the appropriate battery charger at the same time so you don’t get them confused. Or if you already have a charger, make sure you read the charger information to see what kind of battery the charger is for and make your purchase accordingly. When choosing a battery charger for 6 or 12-volt sealed lead acid batteries, match the battery charger’s output voltage and amp-hour range to the battery’s voltage and amp-hour rating. You also need to consider the connection style, usually a plug of some sort, screw terminals or alligator clips.

I hope this information was helpful. There’s really no mystery to batteries if you know what to look for! By the way, I finally found a battery for my power pack about a month ago. It was sitting on the shelf of a Tractor Supply Store, in the electric fence department!