[patrickt]

Conversely, let's wire a 1,000 watt bulb (80 amps) right off the alternator of my car. I start the car up, turn the light bulb on, my alternator serves up the 60 amps that is all it's got, and my battery supplements the needed extra 20 amps, so my ammeter shows I'm discharging by 20 amps. My battery will soon be dead. If I wired that light bulb right to the battery, my ammeter would show that I was charging to the tune of 60 amps but my battery would still be dead pretty soon.