Michael Ash wrote:
In rec.aviation.soaring Alan wrote:
In article "Morgans" writes:
"Peter Dohm" wrote

I 'm confident that the installation is the biggest part of it--especially
when you include enough solar panels to power it all reliably.
Why solar cells? A 7 amp hour lead acid gel cell can be had for about 20 bucks,
and would run a solid state transponder for a whole flight.
One doesn't want to run the lead acid battery down past about 1/2 its capacity
to get a reasonable service life from it, so that limits you to 3.5 AH.

What kind of unreasonable service life do you get if you use the full
capacity, and at $20 each do you care if you use it up faster? Unless you
can count the number of cycles on your fingers that may be the simplest
and most cost effective way to go, although of course I may be overlooking
something important.

According to the Powersonic Technical Manual, you can get about 200
cycles using 100% discharges, and about 500 cycles using 50% discharges,
before the battery is down to 60% of it's capacity. If you need 80% of
the battery capacity, the cycle numbers are about 150 and 400,
respectively. 150 cycles is 3 years or more for most pilots - not bad
for $20.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org