Quote:
Originally Posted by fastd
why/how does it matter if something is wired directly to the battery. In your example, i.e. a fancy audio system (in my case the electronic efi), if it's wired through the fuse box or wired directly through the battery (with an inline fuse), wouldn't the ammeter read out the same way regardless of the way it's wired?
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Let's put a 200 watt bulb on the positive and negative terminal of the battery. Remember watts equals volts times amps, so it's going to draw about 15 amps or so. When the car starts up, the alternator will serve up the amps needed to charge the battery back up plus that 15 amps. All of that will go through the ammeter. When the battery is charged, the ammeter should ease back down to 15 amps plus a little extra for the battery. If you move the bulb over to the other side of the ammeter, the alternator will still serve it, but the current will not pass through the ammeter.