overpowered battery

So when putting a battery in your car, can you have one with Too Much juice? Or 12v is 12v and the amps are there whether you use them or not.
I've swapped battery's between my trucks and the bug before and never really paid it much attention but I got to talking to a friend about it and he was thinking it'd cause damage and fry some stuff.

To my knowledge, 12v is 12v. The only difference being cold cranking amps. Larger engines with more compression and cylinders require more amps to start the engine.

what he said, as long as the voltage is the same, the car will only pull the amps that it needs.

I tried to explain it to my buddy as amps=horsepower. pulling a Jon boat with a powerstroke vs a datson. The boat doesn't care which one, its going to take the same effort to pull it no matter what vehicle you use.
He insisted I was wrong

ask him to think of electricity like water in a hose pipe, as long as the water pressure (voltage) is what the nozzle (radio, light etc) is expecting, the nozzle doesn't care how big a diameter the pipe is (amps).

redneck_davis wrote:I tried to explain it to my buddy as amps=horsepower.  pulling a Jon boat with a powerstroke vs a datson. The boat doesn't care which one, its going to take the same effort to pull it no matter what vehicle you use.
He insisted I was wrong

Sounded like a good example to me. You might try to show the mathematical equation     Current (amps) = volt/resistance (ohms).

Where there is a difference is when you have a large draw (starter [locked rotor amps]or a short) and in those cases the resistance is very low and the larger battery can provide/sustain more power (...or sparks in the case of a short)

...a larger battery might be a little more strain on the alternator or generator when the battery needs charging, but that would only be after an excessively hard start or possibly after sitting dormant for a very long period, etc.