Robert Backer wrote:
I just don't buy this power argument. My panel includes 302, Ipaq,
becker transponder (with encoder)and becker radio all of which run for
at least 6 hours on a single 8.5 ah powersonic battery (exactly the same
dimensions as the typical 7 ah battery). I also carry a backup 8.5 ah
battery which I have never had to switch to.

You don't have to buy it, but there are a lot of variables involved,
including the precise mix of equipment (in particular, the current draw
of the encoder at altitude), frequency of interrogation, sensitivity of
the radio to marginal voltage, whether the PDA is charging, age and
temperature of the battery, etc.

I have a transponder and a single 12 ah battery (and currently no room
for another, or for two 7/8.5 ah batteries), usually I can count on
around 5 hours before I start losing the radio. Yes, things would be
better with a backup battery, and before Kinsell comes out of the
woodwork, yes I could go longer with a 14V system. But, I fly with the
electrical system I have, not the one I might want, so the transponder
usually goes off in the boonies...

Marc