battery question

i use copperplate antiseize on battery contacts for over 30 years, and have
never had a battery terminal corrode
"Bill Turlock" <"Bill > wrote in message
...
> Jeff Wisnia wrote:
> >
> > Jim Beaver wrote:
> > > I've got a '02 Jeep Grand Cherokee. About three weeks ago, it
suddenly
> > > failed to start -- no lights, no chimes, no meters -- this just an
hour or
> > > so after driving it without a hint of battery problem. The battery
(which
> > > came with the car) has one of those little windows in it, showing
green
> > > (which I presume to mean charged). But putting a charger on the
battery
> > > showed (on the charger's meter) that the battery was dead. I put
another a
> > > new battery in the car, the car started fine, and has run without
incident
> > > for three weeks now. The old battery I charged overnight. The
charger
> > > meter read fully charged. I unplugged the charger (still connected to
the
> > > battery) and left it for several days. I plugged the charger back in
and
> > > quickly the meter showed the battery to still be fully charged. I've
done
> > > this several times over three weeks. The old battery is clearly
holding the
> > > charge. The new battery (in the car) is clearly holding a charge.
> > >
> > > My questions: why would a battery that continually holds a charge
suddenly
> > > go dead like that one time, but then easily continue to hold a charge
when
> > > recharged? And, why would one battery that holds a charge continue to
> > > function well in a car when another battery that holds a charge
suddenly
> > > lost that charge in the same car? Connections were always tight and
solid
> > > (I tested).
> > >
> > > Bottom line: is the old battery likely to flunk out again once I put
it in
> > > one of my cars? Is there a difference between holding a charge
sitting on
> > > my garage floor and holding one while hooked up to my engine (when a
> > > different battery is maintaining its charge in the same location)?
> > >
> > > Jim Beaver
> > >
> > >
> > It's unlikely a two year old battery would fail in the fashion you
reported.
> >
> > I suspect that when the problem first occurred you may have found the
> > battery terminal connections "tight", but that didn't mean they were
> > "clean". It's not uncommon for battery terminal connections to develop
> > an insulating oxide film which prevents current flow even though they
> > feel mechanically tight.
> >
> > The simple act of removing the "dirty" terminal from the battery and
> > replacing it will often make the problem go away, which might be what
> > happened when you installed a new battery.
> >
> > The correct fix is to clean the contacting surfaces of the battery and
> > cable terminals by wire brushing them and then put a film of anti-oxide
> > coating on them. (I like Thomas and Betts' "Kopper-Shield" for that
> > purpose, it contains a very fine coper powder which enhances contact.
> >
> > The other possibility is that your old battery has a broken internal
> > strap between two cells which sometimes makes contact and sometimes
> > doesn't, but that's a long shot.
> >
> > Finally, remember that your battery charger is only reporting the
> > voltage of the battery, not it's ability to deliver current. Eight AAA
> > batteries in series will give you twelve volts, but they darned well
> > won't crank over yout engine.
> >
> > Find someplace with a "battery load tester" (and someone who knows how
> > to use it) and check your old battery with it. That'll give you your
answer.
> >
> > HTH,
> >
> > Jeff
>
>
> I wanna get some of that!
> But...
>
> http://www.tessco.com/products/displ...&subgroupId=65
>
> http://tinyurl.com/3kbnf
>
> reports that it's supposed to be used for copper only.
>
> Battery contacts are usually lead, IIRC
>
> Bill "QCWA a/o '99 " Turlock

Jim Beaver wrote:
> Bottom line: is the old battery likely to flunk out again once I put it in
> one of my cars?

yup. it needs to be "load tested". it may have the 12.<whatever> volts,
but once you get the starter to turn over the engine, it might not
supply enough amps.

On Mon, 01 Nov 2004 08:40:41 -0600, Tim Wright
> wrote:

> Here's an old used car dealer trick. If it acts like you describe, pour
> a warm Coca-Cola on the battery terminals. Let it sit for about 10
> minutes then try it. The carbonic acid helps penetrate the grunge, and
> the carbon in the sugar helps restore conductivity.

You don't want an acid, you want a base. The crud is acid. Use
baking soda, not Coke. Coke is for cleaning windshields, although I
recommend using Diet Coke instead.

Mary

--
Mary Shafer Retired aerospace research engineer

Hactar wrote:

> In article >,
> Mary Shafer > wrote:

>>Coke is for cleaning windshields, although I recommend using Diet Coke
>>instead.

> Why diet?
>
No sugar residue on the glass.

charles

"Jim Beaver" > wrote in
om:

> I've got a '02 Jeep Grand Cherokee. About three weeks ago, it
> suddenly failed to start -- no lights, no chimes, no meters -- this
> just an hour or so after driving it without a hint of battery problem.
> The battery (which came with the car) has one of those little windows
> in it, showing green (which I presume to mean charged). But putting a
> charger on the battery showed (on the charger's meter) that the
> battery was dead. I put another a new battery in the car, the car
> started fine, and has run without incident for three weeks now. The
> old battery I charged overnight. The charger meter read fully
> charged. I unplugged the charger (still connected to the battery) and
> left it for several days. I plugged the charger back in and quickly
> the meter showed the battery to still be fully charged. I've done
> this several times over three weeks. The old battery is clearly
> holding the charge. The new battery (in the car) is clearly holding a
> charge.
>
> My questions: why would a battery that continually holds a charge
> suddenly go dead like that one time, but then easily continue to hold
> a charge when recharged? And, why would one battery that holds a
> charge continue to function well in a car when another battery that
> holds a charge suddenly lost that charge in the same car? Connections
> were always tight and solid (I tested).
>
> Bottom line: is the old battery likely to flunk out again once I put
> it in one of my cars? Is there a difference between holding a charge
> sitting on my garage floor and holding one while hooked up to my
> engine (when a different battery is maintaining its charge in the same
> location)?
>
> Jim Beaver
>
>

Jim,
I recently had almost the identical thing happen...
Nearly new high-end battery in a Pathfinder. Dead one morning. A
voltmeter read zero (and I do mean zero) volts across the terminals; less
than a couple of millivolts. Removed and charged - amazingly the batt
held a charge and is still functioning fine a couple of months later.
I measured the load current before replacing the battery, and it was fine
(few hundred milliamps). Terminals were solid and clean. Had to be either
an intermittant open in the battery, or an intermittant short in the car.
I'd go for the former.
Newer batteries have thinner plates so they can get higher cranking amps.
This makes them fail quickly, when they do go. But I've never heard of
one that came back to life after going open-circuit, until our 2
instances.


--
Ray