On Wed, 6 Oct 2004 15:48:26 -0400, MikeG
wrote:

In article , frank1492
says...
Earlier I had reported that I was in the process of recharging a
battery that had been weak and I thought might have lost its water
prematurely. After a trickle charge of 24 hours, a hydrometer test
still seemed to reveal one weak cell (the five balls would rise to the
top, then drop back down. On other cells, only one ball would drop.)
The bad cell was not one of the originally dry ones. Very little
"gurgling" action was shown in the cell while charging.
I had the battery tested at the local Autozone. He put it
through a load test and proclaimed it to be in excellent condition.
(The voltage was over 12 volts.) He said the bad hydrometer reading
was probably due to imcompletely mixed acid and water.
The battery has not been put back into service, but before I
did, I thought I would ask the experts! Did the hydrometer test lie,
or is the cell really NG, in which case the AZ guy was wrong and
I'll have a future problem again. (Really can't imagine the cell would
be bad if the battery put out more than 12 volts under load.)
Once again, thanks so much for your help!
Frank




Lets put it this way. As a battery charges it gives up some of it's
liquid in the form of gas. After some period of time that liquid has to
be replenished with distilled water.

In simple terms..........

Your charging system has a regulator that turns on and off the charging
current to the battery as needed to prevent over charging and excessive
fluid loss.

In one case, if the regulator goes bad the battery recessives constant
charging current and you lose fluid more rapidly then you should.

I've never had one fail the other way, no current to the battery that
is, but I suppose it could happen.

You've never had an alternator go bad on an engine?

Neophyte. :)

The next case is if you have a dead cell. These usually result from
derbies from the battery plates falling to the bottom of the battery and
shorting out a cell. While the battery may show the required voltage a
dead cell will cause a regulator to constantly provide charging current
to the battery and also result in a more rapid loss of fluid.

I'd be more inclined to trust a hydrometer that showed five out of six
cells as ok then the test done where ever. Now, if the hydrometer had
shown all cells as dead I'd be looking for a new one.

However, you can use the hydrometer to suck up and shoot the acid mix in
to and out of the suspect cell to "mix" the acid water and see what
happens. Another option is to put the battery back in and go out and
bounce the boat of a few wakes then retest with the hydrometer.

Good advice, but I'd be concerned about the levels of electrolyte.

I've had it happen to me - the electrolyte mix was way low in one cell
- improperly filled - and it didn't show up until a couple of years
later.

There isn't any reason for one cell to be low on electrolyte and the
others ok - it just doesn't settle that way.


All the best,

Tom
--------------

"What the hell's the deal with this newsgroup...
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Bilgeman - circa 2004