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Battery Math

There’s more to batteries than just making your game controller work.

Look around you. How many things can you see that have a battery? Some things, like phones, computers, and tablets, have built-in, rechargeable batteries. Electronic toys, smoke detectors, and countless other things in your life have disposable batteries. The type of battery, the voltage, and even the configuration of batteries is important. There’s even some math involved. So if you want to learn more, keep reading.

What’s inside?

For a long time, there were mostly two kinds of batteries: alkaline and lead-acid. At the core, all batteries are the same—two or more materials interacting to produce electrons through an electrochemical reaction. The two materials, referred to as electrodes, are either positive or negative. That’s why batteries, like magnets, have positive and negative sides.

Popular types of batteries:kid

  • Alkaline – Zinc and manganese dioxide in an alkaline solution of potassium hydroxide. These are found in everything from TV remotes to smoke detectors.
  • Lead-acid – Lead plates in a sulfuric acid and water solution. Most commonly found in car batteries.
  • Lithium – There’s a few different versions depending on the use. These are showing up in everything from hearing aids, power tools, and the batteries driving electric cars.

Volts matter

Too many volts going into a device and it will get fried. Too few volts and it doesn’t have the power to run. Different batteries come in different voltages. A typical alkaline battery is 1.5 volts. The boxy 9-volt batteries are different, but we’ll get into that later. Lead-acid batteries tend to be 12 volts and lithium batteries are all over the place with voltage, with some even powerful enough to run refrigerators.

Size doesn’t matter?

The batteries you buy to put in your remotes, toys, flashlights, and other small devices come in a lot of different sizes, typically ranging from AAA to D. All those cylindrical batteries produce 1.5 volts. The larger batteries simply last longer. You can actually power things off smaller batteries by jamming some aluminum foil on one side – be careful not to cross positive to negative as that would create a short and possibly destroy what you’re using.

The boxy 9-volt battery is usually six AAAA size batteries in one housing. Those AAAA batteries are all 1.5 volts, but the way they are wired, they create 9 volts. This brings us to our next section.

Serial or parallel

The orientation of batteries inside a device matters. Here’s why:

  • Serial – When you hook up batteries in series, or in a serial configuration, they go positive to negative. This can be done with one long line or wires bridging the gaps. Setting batteries up in series also multiplies the voltage of the batteries. Two 1.5-volt batteries in series are three volts and this is why a 9-volt battery, with 6 AAAA 1.5-volt batteries inside, produces 9 volts. Multiply 6 by 1.5 and you get 9 volts.
  • Parallel – When batteries are set up in parallel, all the positive terminals are attached to each other, and all the negative terminals are attached. While this doesn’t increase the voltage, it does mean the batteries last longer. Depending on how the device was designed, a larger battery may not be practical, so you can wire up a lot of small batteries to fulfill the same purpose: longevity.


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