WHAT IS A BATTERY ?
This may seem like a dumb question but stick with me because this is important . A battery is a storage device for electricity in much the same way as a water tank is a storage system for water .
The difference is , instead of storing litres of liquid , a battery stores amp hours of electricity . The reason we rate a battery ’ s capacity as a function of time will become obvious later . For now , you can think of a 100Ah battery in much the same way as a 100L water tank .
Why do we rate batteries in amp hours , not just amps ?
Electricity is not water , obviously . Unlike electricity , water occupies a space . You fill up a water tank and the water takes up the space inside . Electricity is the movement of electrons through a substance , like the metal in wires or the chemicals inside a battery . The more electricity that passes through a substance , the higher the amps . Batteries are all about how many amps you release over time . This is why we rate them in amp hours .
How does charging and discharging a battery work ?
Going back to our water tank analogy , consider how a garden watering system might work . Let ’ s say you have a 100L water tank full of water and you attach an outlet hose and sprinklers to water the garden .
Sprinklers come in different sizes . The larger they are , the more water they use . They are rated in litres per minute . So if you have a 100L water tank and you have a single sprinkler rated at 10L per minute , you can water your garden with that sprinkler for 10 minutes before you will run out of water .
It ’ s the same with batteries . If you have a 100Ah battery and you run a TV that draws 10A continuously from it , you can watch television for 10 hours before your battery is completely flat .
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