I know that a car battery can provide 1000amperes for starting while other components only need a few amperes to work. I thought that loads "ask" the battery for some electricity and the battery obliges.
I just recently bought USB ports that slot perfectly into one of the empty dashboard slots. They came with a glass fuse that was already blown.
I went and took out the blown fuse and closed the circuit to energize it (parallel connection to cigarette lighter | 15amp fuse.)
I thought I had a basic understanding of electricity in cars and that the USB port would never draw more power than what it needed. I just wanted to see those LEDs light up! and then it got fried instantly - it didn't even light up. I just smelled burned electronics.
I guess it didn't pull more than 15amperes because the cigarette lighter circuit was still working. But why did it fry itself after being energized? I know that the cigarette lighter circuit pretty much works as if it is directly connected to the battery(right??) - there's no electronics that regulates current on it right?
Am I wrong that in a car, the loads pull the amperes and that it is not the battery pushing it?
Did the USB port circuit pull too many amperes and fried itself, or did the battery push the amperes that the USB port circuit couldn't handle it?
I'm very confused because my 220V AC plug in water heater is just a hunk of metal and it doesn't pull 1000ampere from the wall.
So again, do loads pull the amperes, or do power supplies push it?