Wouldn’t it be great if you could look at a battery and tell how many amps it was holding at any point in time? Unlike a fuel or water tank, a battery has no mechanical sender that can float up and down, and then convert the current volume to a readable number. With so much riding on the state of charge of our batteries, how are we supposed to guess how full they are?
Let’s look at our options.
TANKS OF AMPS
Batteries are tanks, of a sort. Inside the plastic box are cathodes and anodes immersed in an electrolyte that facilitates the transfer of electrons. But we can’t see electrons or stored energy. That’s where meters come in. In the most rudimentary sense, a voltage meter can tell the current battery voltage, which can allow us to make certain assumptions about the battery state.
But that doesn’t tell the whole story.
If a battery’s only purpose is to start an engine, like in a car, then a manufacturer can specify a certain size and type of battery capable of turning over an engine fast enough to start when it’s cold. The manufacturer can then install an alternator that will produce enough
