Battery life when running a transponder

On Jul 2, 11:35*pm, Hal wrote:
On Jul 2, 8:38*pm, Henryk Birecki wrote:



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!)- Hide quoted text -

- Show quoted text -

With a becker transponder, 302,303, Dittle radio, and pda 4700 I get
about 3 hours on one 7amp/hour battery. *Most of the flight at 14k and
above. *When I fly in congested areas altitude is lower but 3 hours
seems to be about all I get there also. Older batteries get less. *I
also have a hook-up for PCAS but I was not using it this week (in
shop). *The solar option on the glider would be nice as that helps.

8AH and 9AH 12v batteries in nominally the same form factor as 7AH
(varies a bit by manufacturer) have become available for $18-$30.
Last 8AH batteries I bought were $15. Guess I wonder why some are
still using 7AH batteries.

My LAK-12 has builtin boxes for two 12AH (or larger) batteries and
room for insulation;^)

Frank Whiteley