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

On Jul 2, 12:21*pm, 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!)

I run the following:

- Becker 4401 175W
- Becker 4201 Radio
- Cambridge GPS-Nav
- Cambridge L-Nav
- EDW Micro-recorder
- Compaq 1550 PDA

I operate just outside the New York Class B airspace, so
interrogation is essentially constant. All of this runs for a typical
5 hour flight off one 12V/12AH battery with voltage down to around
10.9-11V at time of landing. I have two of these batteries, so
plenty of reserve for long flights. Operations include winter ridge
runs at ambient temps of around 20F, but those are limited not by
battery but by cold soaking of the pilot.

P3

Thanks for all the answers so far. It is not specifically for me to
fit in my glider, though I am considering it for when the European
system will allow me to, but in connection with a paper I am writing,
so I wanted a rough idea for the benefit of anyone with limited
battery capability. Some UK potential users would be mainly lowish
level thermal soaring, but there would be times when visiting wave
sites and climbing to FL 195 or higher, sometimes for extended
periods.

Also, as more flying things get TCAS, there will be more
interrogations. I thought gliders around Reno and similar high fliers
might have some useful experience.

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

hretting wrote:
Operating a 12v with a 2v (both 8amp/hr or greater) piggybacked to
it , running a 302, PDA, borgelt 400, Becker radio, and an old Terra
transponder gives me about 6 hours before I hit 10.5 volts on the
"left-over" meter.

10.5 volts is "100% discharge" for a 12 volt battery; it would be 12.25
for a 14 volt system. Taking the 14 volt system to 10.5 volts puts the
battery into deep discharge and potentially much shorter life, while
getting very little extra amp hours from it. The shorter life of the
over-discharged battery would quickly remove this small benefit.

I then switch to battery #2 and enjoy the ride.
Starting with 14v gives me the life boost I need. If I "dedicate" a
battery to just the transponder, I guess in excess of 8 hours. Wrap in
foam pack and it should outlast your Oxygen. How's that for "battery
life".

Dedicating a battery to the high-drain Terra might give you more hours
than the current setup (the lower the current draw, the more amphours
you can get from a battery), extend the life (years) of your batteries,
and eliminate the need to switch batteries.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Hal wrote:


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.

Your setup sounds like it would have less than 1 amp draw, which would
give almost 6 hours off a new 7 AH battery. Have you measured the actual
draw? What is the battery voltage at the end of 3 hours?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Jul 4, 1:16*pm, Eric Greenwell wrote:
Hal wrote:

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.

Your setup sounds like it would have less than 1 amp draw, which would
give almost 6 hours off a new 7 AH battery. Have you measured the actual
draw? What is the battery voltage at the end of 3 hours?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Not very scientific but I go until the dittle radio starts blinking
then I switch to battery 2. Maybe I should look into where I am
buying the batteries. They are power sonic ps1270f1 purchased at a
local electronics store.

Hal wrote:
On Jul 4, 1:16 pm, Eric Greenwell wrote:
Hal wrote:

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.
Your setup sounds like it would have less than 1 amp draw, which would
give almost 6 hours off a new 7 AH battery. Have you measured the actual
draw? What is the battery voltage at the end of 3 hours?

Not very scientific but I go until the dittle radio starts blinking
then I switch to battery 2. Maybe I should look into where I am
buying the batteries. They are power sonic ps1270f1 purchased at a
local electronics store.

But first, measure the current drain of your panel, and measure the
capacity of your batteries. If you do get new batteries, fully charge
them and measure their capacity, so you know you got fresh ones.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org