Ron Hevans (?), whose call I no longer have, asked a question about using a
combination of deep cycle battery and charger to power his shack. I have
been using such a combination for over 6 years.

Ron's proposed configuration: "deep cycle trolling batteries, their fully
automatic model PP1.5A Everstart Battery Tender, and a rubber maid box with
cover to hold the battery."

and asked:

"I have never used this setup before having always used a 110V or 220V to
13.75V power supply.  Is there any down side to this?"

Like I said I have used such a set up, a deep cycle battery and automatic
charger for over 6 years. I get about 3 years of useful life out of the
battery with this set up. There is really no down side to this as far as I
can tell. There are three things you should be aware of:

1. The biggest caution is to put the battery in a case so if the acid gets
out it will not spill and damage things. The favorite woman in your life
will not appreciate this. I have experience with this from my mother, wife
and dog. On the other hand, my father thought it amusing and casually asked
my mother for the baking soda. He was a chemist.

2. The next biggest caution is to check the fluid level every month and add
distilled water if needed. That is assuming that you do not have a
"mainteinance free" battery. This monthly maintenence will go a long ways
to keeping your battery alive, particularly if you occsasionally overcharge
or fully discharge it.

3. The next biggest caution is not to over charge or over discharge the
battery. Even with an "automatic" charger I would not leave it connected to
the battery all the time. Disconnect it or turn it off when a full charge
(13.8 V for a "12 V" battery) is btained. I usually run the charger
whenever I am operating and turn it off when I leave the shack. I make sure
the battery is fully charged before an operating event such as SS, Field
Day or Fox hunts.

I monitor the battery voltage during use and charging with a digital meter.
An Amperemeter in series with the charger would help also. My old charger
used to have one, but my new one just has an LED that chages color when the
battery is fully charged. I intend to add an Amperemeter. Holiday project?

I have over charged batteries and discharged them completely, both of which
substantially (half or more) shortened battery life. Under charging will
also damage the battery, so try to make sure that you fully charge it.

A good deep cycle battery should be good for several hundred
complete charge/discharge cycles before it "dies".

I get about 3 years out of mine. This includes one or two complete
discharges and maybe 1 or 2 over charges. Any more and you will be forking
out $65 for a new battery soon.

Sam's Club or Costco generally have the best prices on deep cycle
batteries.

With QRP you should be able to get a week of continuous operating out of
even a small deep cycle battery. With a 100 watt transceiver you should be
able to get a day or so of continuous operating. I found I could go two
weeks of casual operating at the 100 watt level, 2 to 3 hours a day, before
the battery is too low for normal use. I would expect 2 to 3 months of
casual QRP operating to be reasonable to expect from a fully charged battery.

You can use an automobile battery in this fashion, but they are not
designed for complete discharge. 3 or 4 heavy discharges and the battery is
gone. If you already have an acceptable automobile battery go ahead and use
it, but if you are buying a new battery get a deep cycle one.

I hope that this helps. I have posted this to the list as it seems like it
will be of general interest. Time for the MLS cup to start. See you later.
- Dr. Megacyle KK6MC/5