"mugwomp" wrote:
"Lem" wrote in message ...
Will an automatic car battery charger trip out at the correct point
if the battery is left connected to the car?

If the charger works correctly with the battery out of the car,
it will work equally well with it in the car. The only thing
left electrically connected to the battery is the clock in your
radio! So there is no significant difference, in or out.

I don't want my charger to keep pumping current into my battery if it
is fully charged in case my battery suffers some sort of damage!

That is *extremely* unlikely. However, what you don't want to
do is connect too large a charger. They virtually all adjust
down to some minimal charge, but generally the higher the
maximum charge the higher the minimum charge too. For example,
any charger from 1 to 10 amps is probably absolutely safe. At
about 10 amps, it starts getting iffy. I'm not sure I'd want to
leave a 15 amp charger connected too long. I certainly would
not leave anything connected that can put out 20 amps or more.

(Note that I've lived in the, ahh, cooler parts of Alaska for a
few decades, and I rather like the idea of hardwiring a 1A
charger into the system, along with a block heater and an oil
pan heater, for winter use. Lots of people put a heat blanket
around the battery, or put a heat pad under it; but that just
keeps it warm and doesn't top off the charge. A 1A trickle
charger keeps it warm and charges it, and doesn't use nearly as
much electricity.

Thank you for any views.


If your battery is good, it should be OK
If your battery develops a short, it could blow the top of the battery off.

That might indeed be true, but if so it has absolutely nothing
to do with whether the battery left connect to the car or not.

And... I haven't heard of anything like that in at least 30
years or so.

Cheaper batteries do this sometimes, they keep sucking the amps + never
charge up.

Dead batteries do that, cheap or otherwise.

If your battery voltage is less than 10.5 volts, it probably will never
charge

Not true. But, if you put a charge on it for hours, and
immediately after it is removed the voltage goes to 10.5 volts,
the battery is a gonner.

Heck, I just left a dome light on in my truck the other day and
ran the battery down so low that the clock in the radio actually
stopped. (That must be down about 5 volts or less.) I'm not saying
that is good for the battery (and trying to rapid charge it would
certainly be worse than not), but a nice slow 5A charge for a couple
hours put it right back where it was.

--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)