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.


Ed K7AAT

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

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