driving time needed to charge battery.

2011 Nismo#91

20 min it just a cover all for all cars, be it an old school large displacement v8 that might take a bit if time to start or just a car with a cheap alternator/charging system. It probably takes a few hundred amps to start our car for a second or two. It should take more than 10min to make that back. If your dd for less than 10min there are other issues to worry about too, like engine not getting up to temp before you shut it off again. Alternators do charge batteries, they just do it slowly usually at only a couple amps, where a auto battery charger can do it at 6 or 9 amps, which is why if you have a dead battery and get a jump after 30min or an hour you can shut your car off and start it normally.