On 08/20/05 05:06 pm Ed tossed the following ingredients into the
ever-growing pot of cybersoup:

But won't an unsealed (i.e., NOT "maintenance-free") battery lose water
by evaporation even if it's not overcharged? Otherwise why the need to
check the electrolyte level regularly?

Not meaning to get this tread off on a tangent, but the above comment
prompts me to point out that even "maintenance free" batteries AREN'T,
necessarily. On many occassions I have found it necessary to peel back the
paper cover on automotive maintenance free batteries, remove the exposed
cell caps, and add water, especially after a year or two operating in a hot
climate. I don't believe marine type batteries would be any different in
this regard.

Just to complicate matters, I eventually found the Web site for these
batteries (the only marking on it is "Stowaway Tournament"; I had bought
it at Sam's and assumed it was a "store brand," but it's made by -- and
acknowledged by -- Exide). Somewhere in the FAQ they say that they are
"maintenance free" but also "maintenance accessible." How's that for
confusion?

Perce

Percival P. Cassidy wrote:
On 08/20/05 01:37 am ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

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?


But won't an unsealed (i.e., NOT "maintenance-free") battery lose water
by evaporation even if it's not overcharged? Otherwise why the need to
check the electrolyte level regularly?

Because the battery may get overcharged in service. But
I've had a number of cars over the years that had "regular"
batteries (non maintenance free). The batteries rarely
needed water - maybe once or twice a year - and were
never even close to a pint down. I have 2 non-maintenance
free batteries that were picked up at the side of the road.
I've had them for almost a year, and the electrolyte
level has not dropped. These batteries are not on a charger,
they just sit there. I have another that is on a float
charger for 100% of the time, and has been for almost
2 years. The electrolyte level has not dropped.

Ed




Perce

On Sat, 20 Aug 2005 21:06:12 GMT, Ed wrote:

Not meaning to get this tread off on a tangent, but the above comment
prompts me to point out that even "maintenance free" batteries AREN'T,
necessarily.

Some of us refer to such batteries as "maintenance resistant".

With regard to three-stage charging:

I use at Size 31 - 100 AH - gel-cell battery as the main power
source for my radio equipment. Gel-cells are REALLY sealed and can
be operated in any position. They do not have vent caps, hidden or
exposed, and as the name implies, has a gelled electrolyte rather
than a liquid electrolyte. Truly maintenance-free discounting the
need to check the connections for tightness and corrosian from
outside sources.

I recently put a new charger designed for gel-cell charging into
service. This is a professional type charger, not an automotive
charger (with price to match), and it has a specific setting
(dip-switch on control board) for gel-cells. It was recommended as
the proper companion to the battery by the local industrial battery
supplier.

In addition, if the current drawn by the load while the battery is
being charged is greater than 2A (which it is here) a jumper has to
be added on the control board to change it to a two-stage charger
or else the control circuitry will see the load current as charging
current and adjust the voltage upwards to compensate.

I have also found that when in "charge" mode, the DC output has a
60 Hz component which needs to be filtered between the battery-charger
junction and the load. One more thing that "they" don't tell you
in books or teach in courses.

--
73 de K2ASP - Phil Kane
(Regsitered Professional
Electrical Engineer)

I concur with Phil. Gelcells are the true maintenance free battery of
choice for a ham shack. I have run my ham shack off 12V gelcell battery
banks for at least 25 years. I have always simply floated the battery
with a regulated 13.6V 4A power supply. It charges the battery as needed
and floats it at 13.6V when the battery becomes charged; no danger of
overcharging. If the power goes out, there is no need for switch over . .
.. shack is still running off the battery. About every 6 or 7 years I
replace the battery(s).

More recently I have pulled the AC power supply off in favor of 55watt
solar panel with home brew regulator ..... set for 13.6V max. Still works
like a dream.



Ed K7AAT

On 08/19/05 12:19 am Ed tossed the following ingredients into the
ever-growing pot of cybersoup:

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?

I think the battery is bad. I may be remembering wrong, but I seem to
recall that SG should be around 1.230 for lead acid cells, I think. Also,
nominal open circuit voltage on a freshly charged battery ought to be at
LEAST 12.8 volts.

Oops! I got an extra "1" in there for the SG. It should have been 1.175.

Anyway, I did a random series of charging -- sometimes on the 12A
setting (although the ammeter never read that high), sometimes on the 2A
setting -- and resting cycles, adding water as needed. The SG came up to
1.265 (the bottom of the green on my hydrometer), but the "fully
charged" indicator on the charger did not come on.

I then bought a "Vector" 2/6/10A microprocesor-controlled "smart"
3-stage charger (on clearance for a good price) and hooked that up.
After a few hours, it showed "FUL"[ly charged], then switched to
"FLO"[at]; in the latter mode, it is supposed to monitor the battery
voltage (currently 13.8) and "top it up" as needed.

So perhaps this ill-treated battery is not a goner after all.

Thanks for your help.

"Perce"
(aka Alan NV8A)

On 08/16/05 11:24 am Percival P. Cassidy tossed the following
ingredients into the ever-growing pot of cybersoup:

I have a 115AH deep-cycle battery that I bought as a stand-by battery
for my amateur radio station. It has been in a "battery box" on
trickle-charge (using a charger with a "deep-cycle" setting) for most of
the time since I bought it over a year ago, and it has been called on to
supply power only a few times.

Recently I noticed that the "fully charged" LED on the charger was not
on and started investigating further.

Having not encountered any batteries in the last few decades that have
not been sealed and "maintenance free," I was surprised to find tiny
print about checking the electrolyte level every 30 days -- but even
then it took me a few minutes to figure out how to get access to the
cells to check this.

Anyway, when I removed the cunningly disguised covers, I found that the
cells looked totally dry, and each took close to a pint of distilled
water to bring the electrolyte level above the plates.

The battery has now been on charge for about 20 hours at the charger's
12A setting, but most of the time the ammeter on the charger has shown
only about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?

At one point the new three-stage charger did indicate "FUL"[l], then
switch to "FLO"[at] after I had left the battery on charge for many
hours at varying charge rates, but after discharging it again down to
11.2V I couldn't get it to recharge satisfactorily: the charge rate
would stay at 10A and the battery would get very warm.

I then realized that the free replacement warranty was good for 18
months rather than 12 and that I still had a few days to go. I took it
back to Sam's, and they replaced it free without checking anything other
than the date on the receipt. They didn't put it on test in any way and
didn't even check the electrolyte level. So now I have a new battery
with a new replacement warranty good for 18 months and pro-rated after that.

AND now I know that I'm supposed to check the electrolyte level every month.

Thanks, everyone, for your input.

Perce