wrote on 3/7/2017 4:25 PM:
3) my impression (data is hard to find) is that battery lifetime (number of charge-discharge cycles) gets much shorter if a battery is routinely discharged more than 50%

LiFe batteries "lifetime" is generally not affected by discharges as low as 80%.
The 50% number you mention is just a rule-of-thumb for deep cycle lead acid
batteries, and lead acid "lifetime" is substantially reduced if it's routinely
discharged to 80%.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf