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by serf 85 days ago
you're correct. a '12v ICE' alternator generates up to 14.8-15.2v. Most automotive stuff can operate between 9ish-16ish-v , of course totally depending on the product.

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.
2 comments
kube-system 85 days ago
Even just a "12v" automotive battery itself is mostly dead if if actually reads 12.0V. Fully charged is around 12.6 or 12.7. If a car had an electrical system that actually ran at 12 volts, the battery would always be dead.

"12v" in reference to anything automotive is very much a nominal reference.

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londons_explore 85 days ago
Whilst cranking, an ICE car will drop to around 6 volts (then maximum power is extracted according to thevenim's theorem).

That means all computers etc will work at 6v.

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toast0 85 days ago
> Whilst cranking, an ICE car will drop to around 6 volts (then maximum power is extracted according to thevenim's theorem).

> 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.

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cogogo 85 days ago
Interesting. I now know why my windshield wipers quit for a sec when my vw auto stop/start kicks back on.
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Maxion 85 days ago
Not a car engineer, but those motors can be pretty high A, so this could also just be a feature that helps the starter get as much power as it can while cranking.
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bluGill 84 days ago
Ignition switches were turning off the wipers and other such extras in the 1980s. Probably longer but I'm not old enough to remember
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HeyLaughingBoy 84 days ago
Some accessories are disconnected while cranking so the battery can supply as much current as possible to the starter.
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bluGill 85 days ago
The specs say no less than 6volts. In the real world when the temperature drops down to -70F or colder and batteries get old the voltage goes well below that: deal with it.
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