Re: voltage low on car battery

On Thu, 05 Feb 2009 02:01:50 -0500, E Z Peaces <cash@xxxxxxxxxxxxxxx>
wrote:


**WE went over the arithmetic on this when I took high school
chemistry, and it's pretty simple and clear once you see it done. It's
not black magic that the voltage continues to a much higher percentage
of normal than the perecentage of charge is.

I'd like to know more about the arithmetic. It seems to me that if the

High school chemistry was 46 years ago. I don't remember the details.

voltage of a certain chemical reaction were 2.1, a 6-cell battery
measured with a 10 megohm meter should read 12.6 whether 1% charged or
100% charged.

For sure not. The amazing thing to me was that the voltage stayed as
high as it does. But given your expectation of 12.6, that shouldn't
amaze you. :)

It did happen that everytime I left the lights on for more than an
hour, again the car woudn't start, even with a jump. I used to crawl
under the car, remove the nut, clean the cable end with a knife and
put it back togehter. By the second or third time this was too much
work, too dirty and time consuming, so I just reached down, grabbed
the cablen, and twisted it around the solenoid stud. 10 degrees or
less was enough to make the car start.

I thought about replacing the battery cable--there must have been
something different about it, but I learned not to leave the lights
on.

Neighbors kept calling me when their battery ran down. It seemed to be
the regulator built into their Delco alternator, and I couldn't find the
problem. One day they phoned when their car wouldn't start at the post
office. I happened to touch the positive battery cable and it started.
They'd had somebody replace their starter and the cable wasn't
tightened down at the starter.

They often get dirty in there when they run without being tightened.
Dirt makes resistance, resistance makes heat and a voltage drop. Or
in some other way it doesn't work.

Everything had always looked good idling in their driveway, but I guess
sometimes on the road the loose connection would confuse the regulator.
My neighbors called me a fool for not fixing their car sooner. They
considered me their fool because I helped them for free.

These are the same people whose battery you are working on now? They
sound very tactful.
.

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