It's not just the wire size, but also the length of the wire. A 10 gauge wire can carry 200 amps
at 10 feet and 36 amps at 25 feet. There is a specific resistance per foot of wire.
You may have never seen larger than a 10 gauge, but that does not mean it's not used. I have a
T4 gauge wire from the alternator to the battery. My alternator is rated at 150 amps. Look at some
cars with a high powered audio system, if done right then they will have a larger than 10 gauge
wire.
The less voltage drop across the wire, the more that gets to the battery and charges it.
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