On Wednesday, March 1, 2017 at 2:30:05 AM UTC-8, Roy Garden wrote:
(schnipp)
We really need to stop faffing about with batteries invented 2 centuries
ago to try to run modern avionics.


Agree the old SLA stuff is rubbish.
You can as stated "get away with" charging "SLA replacement" LiFePO4 packs on almost anything, including a direct connection to your car's cigarette lighter.
But not a good way to preserve the life of the battery.
Thanks to all posting comments and results on multiple deep discharge! I'll give it a go when the weather is nice enough to pull the fuselage out.
Jim