Put a voltmeter on the battery terminals of a regular car at 2000rpm and note the voltage. You'd be surpised (the alternator can produce as high as 15V on some cars).
13-14v is normal in all 12v automotive systems as the charging voltage
So the alternator has to put out at least something higher than if it’s planning on recharging the battery after 500 to 700 amps have been pulled from it for a few seconds to start the engine.
It's a bit perplexing that those lead acid systems are referred to as "12V" systems when that figure is effectively the 0% voltage, whereas 3.7V for single Li-ion cell is the 50% voltage.
e: also, ICE transients can be in kV range, coming from ignition mechanisms. I've heard that you can literally measure engine RPM by selecting 1/dt on an oscilloscope and dividing that by cylinder count.
One minute you might be accelerating and the onboard voltage drops as the battery supplies most of electricity. Then, as you reach the crest of a hill and start engine-braking, the car frantically tries to convert all the available kinetic energy to electricity, raising the onboard voltage to quickly charge the battery.
Which in practice means that they do a very miserly job charging the battery and are a ton more sensitive to a battery being in less than tip top shape so you can expect your battery lifetime to go down.
But it's a "win" because they pushed the serp belt change outside of whatever interval the reviewers who calculate TCO care about and they saved .000003mph in the process.
Not understanding this sentence. Most running ICE vehicles product closer to that 14.4 than 12v. I think a standard controller would have worked fine?
of course this is just a modern interpretation. older stuff runs at 6v and some weirdo offbeat cars have a 24v/48v rail sitting around somewhere. Cop cars often had alternators that put out weird voltage ranges for certain equipment, or dual 12v for high amperage output.
"12v" in reference to anything automotive is very much a nominal reference.
That means all computers etc will work at 6v.
> That means all computers etc will work at 6v.
Not necessarily all of them. Plenty of stuff will drop out while cranking; hopefully not the computers that run the fuel injection and ignition, though.