Percival P. Cassidy wrote:
On 08/18/05 04:47 pm ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

But are you saying that the "Automatic - Deep Cycle" setting on an
"ordinary" battery charger (it's one I bought originally for the car
batteries, but the "Deep Cycle" setting seemed like a bonus) is not a
reliable way of keeping the batery in good shape?


Aside from attempting to rescue his battery, the OP has got
to fix or replace that charger


^^^^

We already have strong evidence that the charger you used
cooked the electrolyte. I made no reference to the "universe"
of ordinary chargers - I was thinking specifically of yours.
But you raise a good point, expanding the question - and others
have answered.


Well, we don't know how much the charger contributed to the problem,
because the electrolyte level wasn't checked for more than a year
because I hadn't realized that it's not a "maintenance-free" battery.

Whatever charger you use, you need to verify that it is
doing the job properly. Consider building an add-on
monitoring/control circuit. Perhaps a comparator with
a sonalert to notify you that something is wrong with
automatic charger shut-off when the voltage exceeds
some level. I built a comparator into an ordinary
10 amp charger to turn it on and off automatically.
A 339 works fine - 4 comparators in one chip, so you
can have a voltage too low output turn the thing on,
and a voltage too high turn it off. Still have two
comparators left over to use as you like. Add a couple
more 339 chips and you could add a 10 step led
voltage monitor, for example.


While looking for a hydrometer today, I noticed "Vector" brand "smart"
chargers (10/6/2A and 6/4/2A) that claimed to have 3-stage charging
circuitry and to be suitable for car batteries, deep-cycle batteries,
and gel-cell batteries. Are these likely to be any good?

The battery was still warm, and each cell was still bubbling slightly
after the thing had been disconnected from the charger for about 3
hours. The SG of each cell was pretty much the same at approx. 1.1175,
and the voltage across the whole battery was 12.4. When I put it back on
charge, the voltage rose to 13.3.

What do you think?

Perce

I can't comment on the chargers you mentioned - I don't know
anything about them. But I wouldn't trust any charger until
I have verified that it 1) does charge the battery, and
2) does not overcharge the battery. And even that has the
possibility of error. A charger that works fine at 50 F ambient
may not work right at 80 F. So my testing, at 50 F, may
not reveal a flaw that occurs at 80 F. (Or vice versa.) The
terminal voltage - the voltage across the battery at which the
charge should terminate - varies with temperature.

Concerning your battery's SG: either your SG tester or the battery
is bad. The SG reading is too low. To verify, check the specs
on your battery with the manufacturer to see what they say the
SG should be. I believe the battery is bad, as there is
corroborating evidence from other facts besides the SG reading

Regarding my comment that there is strong evidence that your
charger is bad: the electrolyte level didn't go down due to
leakage. The alternative is that it went down due to evaporation,
which is a result of heat, which in turn can be caused by
overcharging. As you point out, we don't know how much of the
electrolyte loss was caused by the charger - but the only
possibility that can be linked to what you have posted thus far
is overcharging. Perhaps there are other factors you haven't
mentioned?

Ed