For me (TERRA transponder with Nixie tubes display) - at most 4 hrs on
14Ah battery before radio (yes) becomes totally unuseable. This is for
flights in the middle of summer at 11-18000ft. Added load from sources
other than transponder is about 500mA.

This year I added a 7Ah emergency battery so I can land without having
to fumble for my handheld which most likely also has a dead battery
.

Cheers,
Henryk Birecki


On Jul 2, 9:21*am, Chris Nicholas wrote:
Can anybody tell me what battery life you get in practice, when
running a transponder from a dedicated lead-acid battery, and what
size battery that is? And what model of transponder is it?

Has anybody measured the actual current drawn during operation, if so
what is it?

I am particularly interested in flights which include some high
altitude, cold ambient operation such as in parts of North America.

I am only interested in modern, solid state transponder operation, not
the older Mode C with a heater for the height encoder.

I have been given figures which suggest that a 7-amp-hour battery
would run one for 12 hours at surface ambient conditions, and I wonder
if anything like that is achievable in practice.

Thansk - Chris N.

Chris N. (In UK, but collecting data from anywhere that has it!)