Battery life when running a transponder

[Chris Nicholas[_2_]]

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!)

[Darryl Ramm]

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!)


Many "modern" transponder installs in the USA will still have a heater
for the encoder. In the USA the Becker ATC-4401-1-175 Mode-C is pretty
common with an external encoder and the most popular encoder is an ACK
A-30 and that has a heater.

There is no single number that is meaningful to answer your question.
e.g. AGM batteries have significant temperature related effects. What
will work fine on one flight won't on another if the electrolyte
freezes. Most glider pilots however don't fly in those cold conditions
(but those who do need to be aware).

What problem are you trying to solve? Do you need to add a battery to
a glider and want to work out how big? For what flight profile? Are
you specifically worried about cold soaking?

This sort of question, prompted me a few years ago to give a talk on
glider batteries, the slides are at http://www.darrylramm.com/glider-batteries/
Hard to follow without speaker notes but you'll see some relevant
things. Do your own power budget, factor in your own battery temp and
aging factors and if nothing else take the manufacturers numbers for
the transponder (and encoder if separate). Or worse case use the
numbers for the Becker and encoder I have in the slides - those
manufacturer numbers are pretty good in practice. More recent
transponders will do better. I'd like to see actual measured numbers
for the Trig TT21. BTW the slides don't talk about circuit breaker of
fuses losses, I just did not have time and have no updated them. Just
don't choose really low value circuit breakers and you'll be fine.
Technical folks can look up the breaker actual specs and add those
into the budget.

So some wild ass numbers... Even a Becker ATC-4401-1-175 with ACK
A-30 encoder (with a nominal power draw around 0.49A) can give around
12 hours off a 7Ah battery at nominal conditions. A typical AGM
battery at 0C might be 15% down on it's spec (measured at 20C). Things
get "interesting" around -20 degrees where the electrolyte in an AGM
battery starts to freeze. The thermal mass and the somewhat natural
insulation of an AGM battery means the internal temp will take a while
to soak down. I had plans of inserting a thermometer into an AGM
battery but never did that. If that is a real concern on say long cold
wave flights you need to look at solar panels, battery insulation, pre-
heating batteries or different battery technology.



Darryl

[Tony Condon[_2_]]

Ive got a Garmin 320 with ACK 30 encoder that is ready to go in the
Cherokee. Perhaps tonight I will be able to get everything wired up and
check the current draw. Im expecting about 1.5 amps between the
transponder and encoder. That will drain my battery moderately fast, but
my "long" flights tend to only be about 3 or 4 hours anyway.


-Tony Condon
Cherokee II N373Y

[Darryl Ramm]

On Jul 2, 11:30*am, Tony Condon >
wrote:
> Ive got a Garmin 320 with ACK 30 encoder that is ready to go in the
> Cherokee. *Perhaps tonight I will be able to get everything wired up and
> check the current draw. *Im expecting about 1.5 amps between the
> transponder and encoder. *That will drain my battery moderately fast, but
> my "long" flights tend to only be about 3 or 4 hours anyway.
>
> -Tony Condon
> Cherokee II N373Y

Remember measurement will be affected by the radar interrogation rate.
If it is not being interrogated on the ground you'll measure a lower
power draw than in practice.

Your excuse in future can be you had to land becasue the battery for
your transponder was going flat :-)

Darryl

[Bob Kuykendall]

On Jul 2, 11:30*am, Tony Condon >
wrote:

> ...Perhaps tonight I will be able to get everything wired
> up and check the current draw. *Im expecting about
> 1.5 amps between the transponder and encoder... *

Tony, if you get a chance please post the measured current draw here
on RAS.

If you'll recall, I suggested the GTX320 a while back on the basis of
having shoehorned one into my HP-18 panel. Eric Greenwell asked about
current draw, and I didn't have a good answer (I couldn't get a draw
value that I trusted) but I was pretty sure it was less than an amp
for the xpdr and only about 200 ma for the encoder. It'd be good to
see what your draw is, even if it is a base draw. If possible, maybe
see what the draw is during Ident when you know its transmitting.

Thanks again, Bob K.

[brianDG303[_2_]]

Of course if you could put even a little insulating foam around the
battery, like layers of 1/4" foam core, it would help, as would
putting your extra sweater or shirt on top of it. As Darryl's photos
show, it's best to keep the chilled beer in another location.



> The thermal mass and the somewhat natural
> insulation of an AGM battery means the internal temp will take a while
> to soak down. I had plans of inserting a thermometer into an AGM
> battery but never did that. If that is a real concern on say long cold
> wave flights you need to look at solar panels, battery insulation, pre-
> heating batteries or different battery technology.
>
> Darryl

[Darryl Ramm]

On Jul 2, 2:14*pm, brianDG303 > wrote:
> Of course if you could put even a little insulating foam around the
> battery, like layers of 1/4" foam core, it would help, as would
> putting your extra sweater or shirt on top of it. As Darryl's photos
> show, it's best to keep the chilled beer in another location.
>
> > The thermal mass and the somewhat natural
> > insulation of an AGM battery means the internal temp will take a while
> > to soak down. I had plans of inserting a thermometer into an AGM
> > battery but never did that. If that is a real concern on say long cold
> > wave flights you need to look at solar panels, battery insulation, pre-
> > heating batteries or different battery technology.
>
> > Darryl
>
>

Brian glad you noticed :-) That beer was drunk during an exhaustive
few days measuring battery performance.

And another comment to the original post. - even the Trig TT21
internal encoder has a heater as do most encoders. But again
temperature issues if any, may be the AGM battery behavior not the
encoder heater load. Some encoders however can have a high current
draw. Even with an ACK A-30 you can easily see the heater kick on. If
that is a problem then insulating the encoder could help. The typical
power consumption from that however is not worth worrying about. I
also would not really consider any encoder "solid state".

Just to make sure there is no confusion, the cavity tubes in older
(non-solid state) transponders have filaments or sometimes rarely
called "heaters" that drew high current (~amps) - entirely different
than the encoder heater.

Darryl

[hretting]

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. 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".
R

[Henryk Birecki]

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!)
>
>

[Hal[_2_]]

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.

[Frank Whiteley]

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

[Papa3]

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

[Chris Nicholas[_2_]]

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!)

[Eric Greenwell]

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

[Eric Greenwell]

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

[Hal[_2_]]

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.

[Eric Greenwell]

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