> In Dan Master's Electrical Maintenance handbook he points out that,
> while driving, the alternator
> supplies a constant 14.6 volts to the battery, and once fully charged
> the battery's internal
> resistance prevents further charging.
I'm too lazy to go check, but I find it hard to believe that's what he said. If
so, it's a gross oversimplification.
> He puts out a disclaimer that he is no battery expert, but
> extrapolates from his observations that
> you probably can't over charge a battery with a battery charger.
First bad assumption : very few battery chargers are accurately voltage
regulated.
Second bad assumption : large trucks do not run at speed for days at a time, and
generally do not keep a constant 14.6 volts at idle. (Even ignoring the fact
they don't keep a constant 14.6 volts even while at speed.)
Of course it depends a bit too on what the definition of "overcharging" is.
It's certainly possible to build a battery charger that will not overcharge, and
such things are commercially available. Generally known as "smart" chargers or
sometimes "battery maintainers", although not all "smart" chargers will not
overcharge. But, they are substantially more expensive than a run-of-the-mill
automotive battery charger and relatively hard to find.
I have completely destroyed batteries by leaving a battery charger on too long.
My charger is pretty old, but I saw almost the exact same unit on sale just the
other day.
Randall
|