Do the math for a second. Lets say our batteries have a capacity of 60
Amp hours. That means that to go from "empty" to "full" would take 60
amps for an hour, or 30 Amps for 2 hours, etc. So we folks with
generators should see the ammeters pegged for 2 hours if we totally
flatten the battery. Well, this isn't exactly what happens, the battery
probably never gets totally flat, and the charging rate tapers off as
the battery fills, but you get the idea. An alternator car, of course
has a lot more current available to recharge the battery, so that pretty
much explains why the generators disappeared.
Example: My Tiger was parked for 4 months, but started unassisted.
Watching the voltmeter and ammeter, it's taken about 45 minutes of
driving until the charging seems to be tapering off.
Example: We stored my sister in law's car for a few months when she was
away on business. A modern Honda. The alarm totally flattened the
battery. We jumped it started and drove it for 15 minutes. It would
not restart. I had my charger dumping in maybe 4 Amps for a couple
hours. It would barely start. We fast idled it in the yard for a half
hour, and it finally started to come back. Even with an alternator, it
took a long time to get it to where it could restart itself. The
battery did last a couple more years after that.
Stu
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