On Wednesday, 30 December 2020 at 01:58:04 UTC+2, Moshe Braner wrote:
I've often thought of adding small solar panels in my glider to extend
the battery life, but when I do the math it makes no sense. Most
gliders have very limited room for solar panels (unless you glue the
flexible type outside the cockpit). I am surprised you got 550 mA,
that's about 7 watts. But that's probably peak, when the panel is
perfectly aligned towards the sun, and not under a cloud, and the
average would be much lower, probably 200 mA or less. Meanwhile people
have been loading their gliders with so much electronics that they say
they need TWO 12AH batteries to last a flight. Let's take the example
of a 1-amp average load, i.e., one 12AH LFP battery (or two SLAs) would
last 12 hours. Add a 200mA-average solar charging setup and that
reduces the load on the battery to 0.8 amps, extending the battery life
to 15 hours. Useful?

I wouldn't bother with solar panels unless my glider was factory equipped with one. My panel draws 830mA and I have 2*7 Ah of battery capacity, but OTOH I like to have one fresh battery to extend my engine in those very cold days.