On Monday, 28 November 2016 03:30:20 UTC+2, Eric Greenwell wrote:

I have a Butterfly vario, Flarm, radio, Mode C transponder, iGlide on
iPhone 6, all of which add up to about 1.4 amps, double your current
draw. My panel is not extravagant, not even including a backup vario. I
wish I had a solar panel(s) to extend the duration the instrument
battery, and charge it on the ground (exchanging batteries is impractical).


Sounds like you have only transponder drwaing current I don't have. It has a large current draw though, especially the older ones.

Are you using LiFePos or lead batteries? Comparasion is diffult because lead batteries give their rated capacity in room temperature with very slow discharge. Try that in cold weather/higher current and you end up with much less capacity. In my experience 8 Ah Lifepo gives over twice the capacity of normal 7 Ah SLA (11 hrs vs. 5 hrs of operation in my glider)