[BARC-List] Battery Operations [try 2]

[Bill N1VUX]

Hmm. I tried replying once, but barc-list@qth.net failed, does it insist on
barc-list@mailman.qth.net now? [Those also on MRAS saw this already once,
cince I cc:'d that list on my reply.]
= = = = = = =

> I'm looking for portable power solutions for operating a mobile rig at
> 12v. This would be for use where more than 5w is needed in an emergency or
> at an outlying area of a public service event.

I got a Vector or Power City belt-pack on discount from Grossmans Outlet in
Brighton; contains two gel-cells, a 12v type outlet, a fuse, and a small,
cheesy inverter (so it can even run small 110v AC devices, with a stepped
square-wave "pseudo-sine"; requires a true RMS meter to properly read it,
don't power anything that gets too hot they say).
  The Ham stores have similar items without the 110v inverter. "Power Pocket"
is a brand I've seen.
  You can also build something similar from a fanny-pack, a long flat gell
cell like video-cameras and bag-phones used to use, appropriate crimp
connectors, and a cigar-lighter outlet on pigtails.  An inline fuse holder
would be a good idea.  You can usually buy wires with the right connector for
gell-cell connectors at one end and Andersen Power Poles at the other from
Howard (formerly displaying "Girlfriend Wanted" banner) at the MIT Flea.
www.emaares.com/ppole.htm

> I remember seeing someone at the Boston Marathon a few years ago (before I
> was a ham) who had a mobile radio in a backpack with batteries and a small
> antenna mast. What kind of setup might this have been?

Probably a couple of alarm-sized (medium-large) gel-cells in the backpack.
Would be fairly hefty, but they'd provide ballast to keep it from tipping over

too; otherwise you need a sandbag or something to stabilize the mast.  From a
real radio hole, backpacking a mobile 10W or 25W or 50W radio, 125AH or 250AH
of batteries, and a mast is almost a necessary precaution -- but generally
running a strategically located magmount on a cookie-sheet or pie-plate from
the 5W HT is sufficient.

> And carrying a car battery around is not all that practical.
> ;-)  Or is that really the answer...

Car batteries have their chemistry & internal passages are designed for
maximum cold cranking amps, or surge loads, with the expectation that the load

will not last long enough to be measured in Amp-Hours, that they'll soon be
well recharged.  They're damaged by beeing discharged long and hard.  For
running radios you really want a battery whose chemistry etc are optimized for

a smaller current (1-20A) for a much longer time instead -- these are called
deep discharge batteries.  "Marine" is a euphemism for deep-discharge.
Deep-discharge gell-cells are you best bet, sealed Marine d/d 2nd best.  You
don't want to deal with non-sealed "oh no, the acid spilled on me" batteries
in an emergency.

One important thing with gell cells and other big batteries is to cover the
terminals in storage, so stray wrenches etc won't short them and cause a fire
or explosion.

73

      William Ricker, ARS N1VUX
      EMA ARES Webmater/NetControl & DEC Suffolk/Metro-Boston
      SKYWARN backup coord, So.NE & Waltham Net Control
      http://www.EMaARES.com/   http://world.std.com/~wdr/
      wdr@theworld.com  a/k/a n1vux@theworld.com @amsat.org @arrl.net