Hi Bob,
As I read Dan's book, he starts by making the case that you can drive a car on
a long trip -- 15/16
hours and the alternator is pushing 14.6 volts at a fully charged battery, and
you don't damage the
battery. What do these alternators put out 35 amps or so? His claim is that the
internal resistance
of the battery prevents further charging (over charging).
It also seems that you can let the car sit for weeks w/o loosing the battery
charge, and then start
it and drive it off for another 15 hours w/o damage to the battery. Some cars
are driven a lot --
Taxi in NYC for example w/o damage to the battery.
Seems to me there must be something different between what a battery charger is
doing to the battery
and what the car's alternator is doing to the battery.
V=IR. Doesn't that say that when the battery's resistance goes up the current
goes down? OK I am a
dummy about electricity, but I always thought the amperage was a function of
voltage and resistance.
You could have all the amperage in the world available -- it didn't matter --
the amperage used was
a function of voltage and resistance. So what does it matter what battery
charger's amperage is?
Maybe the charger increases the voltage when the amperage is increased?
Don Malling
Robert M. Lang wrote:
> Hi,
>
> Perhaps the logic of Dan's claim is true, but if you charge a battery long
> enough, much of the water will boil away and after that, the battery is
> toast. I've done this far too many times... it's possible that the big-rig
> batteries are more like the so-called "marine" batteries which are also
> "deep cycle". Perhaps these batteries have thicker plates with more lead
> on them hence they are less prone to issues related to over charging.
>
> Part of the problem is that the modern batteries seem to have just a
> coating of lead on the plates (as opposed to thick lead plates in the old
> days). Thus, once the plates get sulfided, you can't get them to "shed"
> the lead sulphate (or is it sulphite?) so you can't bring 'em back...
>
> If you "trickle charge" at a very light current (say 50 ma or less), it'll
> take a long time to fry the battery. But at 1000 ma, you can def. fry the
> battery (I'm talking about a 6-cell, lead-acid battery here - sched. 24
> "stock" TR6 battery). I've fried them this way by charging at around 1 amp
> for a coupe of days. I'm talking fried and DEAD.
>
> rml
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