What’s the difference between all the different battery sizes? Why do some need AA and others AAA?
In: Technology
In the main, batteries differ in capacity (amps/milliamps) and electric potential (volts). You can think of electricity as being kindof like water, and a battery as being kindof like a squeeze bottle of water. Capacity, then, measures how much water your bottle holds, in milliamps. Voltage tells you how forcefully the water shoots out of the bottle.
With more milliamps, your battery will last longer. With higher voltage, your battery can be used to achieve more powerful effects, faster. For instance, you can’t start your car engine with 1.5 volts. You need to deliver 12 or more volts to move the starter and ignite the fuel.
AAA and AA and D batteries all deliver the same 1.5 volts. AA and D batteries are simply larger, having higher capacity in milliamps than a AAA battery has. You can, for instance, use AA batteries in place of a D if you have a round adapter for that and it will deliver the same 1.5 volts.
Your rectangular 9-volt battery puts out (surprise) 9 volts, but only holds like 600 milliamps, so it won’t last as long as a AA.
That’s the basics. Next step is understanding that you can put multiple batteries in parallel (for same voltage, more amps) or series (for same amperage, more voltage). In fact, sometimes you can crack open a large battery and inside will just be a bunch of smaller batteries wired together.
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