Can SkyView Power the ACK E04 Serial Interface?

Bill Putney

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Preface: It looks like I have a couple of sources to feed GPS location data to the ACK E04 ELT. The ELT is going to broadcast the last GPS location it got over the serial port if it triggers after an impact. If I depend on a GPS source that is dependent on ships power and I continue in flight for another 30 min at 150 knots before I have am forced down. The rescue crew could be looking a long way away from where I've landed if they take the GPS location as gospel, or at least the won't have the advantage of a GPS fix if they've noticed the satellite gross location differs wildly from the transmitted GPS location.

I could use a spare serial output from my Avidyne IFD 440 Navigator. But that depends on ships power to operate. Or, a serial output from SkyView. That has battery backup for a while if the ship looses power. That would be nice because the GPS location in the ELT could keep updating as long as the SV-BAT-320 battery lasts.

The problem I see is that is looks like the ELT uses about 40 ma at 10-32V to run the serial interface. ACK says to hook that up to ships power. If I do that, I think the ELT will stop receiving GPS data if the ships power dies and there is no advantage gained by hooking the ELT to the SkyView. Then the mis-direction to the rescue crew sets in.

My question to the forum: Has anyone used SkyView power to power that ELT serial interface?

Thanks,

Bill
 

Carl_Froehlich

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Aug 22, 2007
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You are mixing data into the ELT and power to keep the ELT battery charged.

A SkyView serial output will provide the ELT with position information. No problem. For power I suggest proving it via whatever ”AUX” buss you may have for USB plug, panel lights, fans and such. The ELT does not need power to work - that is the function of the ELT battery. Your AUX connection is the power to keep the ELT battery charged until you need it.

Carl
 

Bill Putney

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The ELT battery isn't chargeable. If I'm not using the serial interface, I don't even need to connect anything to that DIN connector that has the serial and the power connection in it. I'm pretty sure that only powers the serial interface, but I'll call ACK tomorrow and ask.

Bill
 

Rhino

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You could fairly easily put a small rechargeable battery with the ELT that would power the serial interface for a short time, and would charge from ship's power. It would add weight though. I don't recall a spare backup battery connection from Skyview, but I haven't checked to confirm that. I'd wait to see what ACK says. They must have had to deal with this question before.
 

Bill Putney

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From Mike A at ACK “
When not activated and power is lost to the ELT GPS data is lost.

While not activated and GPS data stops being transmitted the ELT will retain the last coordinate received for 1 minute then discard it.”

So that answers two questions. 1st, power has to be on the 4 pin DIN connector to accept GPS data. 2nd, If I keep flying for a while after there is no GPS data, the last fix it got will be thrown away and not reported if there is a subsequent “activation” (aka crash).

So, if I want the benefits of having the fix battery backed up so that it’s accurate if “an activation” happens, I need to keep power on 4 pin DIN somehow.
 

Bill Putney

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Back to my original question… The SkyView provides reserve power to a lot of things on the SV bus and to the GPS on a line from the 37 pin D-Sub connector. Has anyone done this? Has anyone had a bad outcome?

I could put another battery out there just to power the that one 40 ma device. But, I’d have to devise a charging circuit. And, some way to cut off the battery power when I want it cut off so that the ELT doesn’t deep discharge the battery. But not cut the power off if there is a system power loss, since that’s what I’m trying to protect against. All that stuff is built into the SkyView already.

It’s not as simple as hooking up a battery. And since this is a Type Certificated aircraft, I have account for all the stuff I do so that I don’t cross into Major alteration territory.
 

RVDan

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The HDX installation manual section 4.3.9.16 discusses the GPS output to an ELT. There doesn’t seem to be a provision for power to ELT. Any loading on the Dynon system regulated outputs that it was not designed for could compromise the system reliability and 40mA is not insignificant. The EMS has a 12V regulated output that can supply a total of 300mA but I am not sure if that remains powered when system power is removed. Given that this is a certified system though, without Dynon data supporting the use of the power output, I think you are treading in major alteration territory. As a DER, I can approve data in support of a major alteration, but the cost might be more then makes sense.
 

JohnAJohnson

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Yes. I am doing it. I spoke with Dynon when I was planning and they said no problem for the amount of current draw, even when the HDX is running on the backup battery. This is the best way to power an ELT, for the reasons you state. Also, I am certificated (177RG).

E04.jpg
 
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Rhino

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I tossed the battery idea in there because you have a certified aircraft, and I imagined the approval process for using the Dynon system as pretty difficult and complicated, if even possible. Using a standalone battery wouldn't be as complicated as you imagine. You wouldn't actually need a charging circuit, and a simple switch or relay would prevent battery discharge. However, if there's documentation from Dynon saying the Skyview connection can be done, all the stuff regarding a backup battery is moot. Using an output from the Skyview would be a far more elegant and desirable solution (simpler too), and the documentation from Dynon makes approval eminently more likely. I would definitely go with that. And although the battery doesn't really weigh that much, I'm always happy to save whatever weight I can.
 
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