“The Matrix is a computer-generated dream world built to keep us under control in order to change a human being into this.”

The Matrix (1999)

While we are still a long way from rogue artificial intelligence enslaving the human race (at least I hope we are), the necessity for batteries remains largely the same. Batteries power most things in our lives. Phones, watches, cars, tools- all of these things are powered in some part by batteries.

Naturally, with so many different devices and applications, there must be many different types of batteries as well. So how do we go about deciding which kind is right for our projects? It’s all about knowing what you need.

Battery Basics

Something you’ll need to know before deciding is what all of the different numbers and abbreviations on our batteries mean. The first attribute is a battery’s milliamp hours, which is expressed as mAh. This number denotes how many milliamps of continuous power the battery can provide in one hour. The higher the number, the more powerful the battery. The second attribute is the nominal cell voltage. This tells you how many volts a cell provides. It’s important to note that a battery’s nominal cell voltage and its actual voltage may vary slightly.

If your battery is rechargeable, then the third thing you’ll want to know is how many functional cycles it has. One cycle is one full use of the battery, from fully charged to fully depleted.

There’s A Lot of Batteries… Like A LOT

Next, we’ll need to look at the different types of batteries there are. The most common type of battery is alkaline. These are the batteries that most people use daily. AAA, AA, C, D, 9V- these are all alkaline batteries. While alkaline batteries will vary in mAh depending on size, they all share the same nominal voltage of 1.5V. The exception to this is the 9V, which, unsurprisingly, has a nominal voltage of 9V; although, if one were to open a 9V battery up, one would find that it is actually made up of 6 1.5V cells wired in series. Alkaline batteries are generally not rechargeable, but are relatively inexpensive.

A general guideline to follow. Different brands and types may have different values.

The next type of battery is the less common, but still widely recognized “watch” battery. These round, flat batteries are usually called coin or button batteries. Unlike general alkaline batteries, button batteries can come in many different styles, types, and chemical makeups. Button batteries typically have a lower mAh value, but vary in their voltage (generally between 1.5V and 3V). Button batteries fit into a category of their own because they can be almost any makeup.

The two most common button batteries, and their usual values.

Another fairly common type of battery is lithium. Lithium batteries (as well as their rechargeable counterparts, lithium-ion batteries) are characterized by having a very high charge capacity, meaning they will last much longer than other types. There are two major downsides to lithium batteries. First is their relatively high price. Second, lithium batteries are also among the least durable battery types. Small punctures or dents can cause the battery to fail or even explode in some (very extreme and unlikely) cases. Lithium-ion batteries are common in cell phones and laptops and are becoming more widely used in military applications as well.

Nickel-metal hydride (NiMH) batteries are another type of rechargeable, roughly equivalent to alkaline batteries, but with a slightly lower nominal voltage. NiMH batteries are quickly replacing nickel-cadmium batteries as they are safer for the environment and last significantly longer. They also aren’t plagued by what is called the “memory” problem, which is a battery’s inability to maintain its effectiveness if it is recharged before being fully depleted.

Lastly, we’ll talk about lead acid batteries. These heavy, bulky batteries are great for high-current applications that don’t require the battery to be portable. You can find the most common type of lead acid battery by simply opening the hood of your car. The major downside to lead acid batteries is their very low cycle count. Even a top-of-the-line one will only last about 800 cycles.

So What Does It All Mean?

Now that we’ve been through each battery and its pros and cons, hopefully you are a little more well-equipped to choose the one that’s right for your project. Is rechargeability a must? No alkaline batteries for you. Is your project small and portable? You probably aren’t going to want the lead acid variety, then.

No matter what your project is, there’s a battery to fit your needs. All you needed was to know how to pick it. Good luck!