On Mon, 10 Sep 2007 13:14:44 EDT, Cecil Moore
wrote:

Estimate the number of hours out of that 12 hours
that you would be transmitting. Multiply that by
the current consumption during transmit. Multiply
the rest of the hours by the current consumption
during receive. Add them together to get an
estimate of the necessary ampere*hour rating
for the gel cell. Be sure to take into account
the minimum operating voltage required by the
hand-held.

I just got through trying to get discharge curves for my station's 12V
Group 27 AGM batteries (for those not familiar with "group" ratings,
this is the size of the battery normally found in compact or larger
automobiles). The manufacturer is Trojan Batteries, a very reputable
battery manufacturer.

What I needed was discharge curves for the battery down to 11.5V which
I have found (the hard way) is the minimum voltage below which most of
my electronic equipment starts going flaky.

From the data that they supplied, for a discharge down to 11.5 V the
AH capacity of a battery is to be derated to 68% of the "industry
standard" 10.5V AH rating.
--

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

e-mail: k2asp [at] arrl [dot] net