Power Failure Questionaire Help

I wanted to start a new thread related to my other thread "Surviving
Flight Recorder Power Failures". Thanks for all your comments.

I plan on asking the SSA to allow me to give a presentation (at the
next convention) on how soaring electronics all bolts together and the
proper wiring techniques. I get a lot of questions on this topic as
there seems to be lots of confusion on the topic. Also when I look
under the "hood" of some sailplanes, I shudder at the cabling jobs that
I witness. And no, contrary to popular belief, ACE hardware does not
have an aviation aisle.

It occurs to me that I want to put together a comparison of how popular
flight recorders handle power failures. Towards that end I have come
up with a few questions to ask the manufacturers. Do you have more to
suggest?

Multiple power sources
1) Can your device support multiple power sources? I.E. multiple
batteries.
2) How do you switch between the different power sources or are the
sources combined? How are they combined (diode, etc)?

Backup Batteries
1) Does your device have a internal or external "backup" battery?
Is it a true battery or another type of device (i.e. large capacitor).
2) How long with the backup power source last?
3) At what main battery voltage does the backup battery engage?
4) Does this battery charge itself from the main battery input?
5) What features are retained or lost when on the backup battery?
a. GPS output (to PDA)?
b. Output to external display?
c. Internal display?
d. Other?

Flight Logs
1) If there is a power outage of short duration, is the flight log
maintained?
2) How long of a gap in time without power is allowed and still
maintain a single log file?