Starting With Dynon On

[Dynon101]

I'm sure this topic has been brought up a number of times however... what protections are installed in the Skyview  system that ensures that the voltage Spikes during and after engine start does not adversely affect the equipment however I have a EMS sensor pin connected to the starter cable and I use that as a starter engagement annunciator on the screen, should I protect that sensor wire with some kind of fuse or fusible link like 28 AWG wire?

Thanks

 

[CGameProgrammer]

For sure the EFIS/ADAHRS/EMS are fully equipped to deal with the voltage spikes, both high and low (if you have the backup battery), when starting. This is confirmed in the documentation. Obviously you want to monitor oil pressure instantly when starting the engine and the only way to do that is to have the EMS and EFIS fully booted up beforehand.

I do not know however if this protection extends to the radio or transponder and I am curious about that. So far I've always been keeping them off during engine start.

 

[swatson999]

It's on page 2-1 of the User's Manual:

SkyView’s robust power protection allows it to be powered on during engine start.
.

 

[swatson999]

As for other equipment..I leave all of my equipment (Dynon XPDR, Garmin radios, etc.) on during start (I don't have an avionics master).

Any modern piece of avionics can handle whatever *sags* it will see during start. And spikes, if you think you're going to get those (most seem to think they're OWTs). Check the TSO or other specs if you don't believe me.

 

[Dynon101]

Thanks for the information on the "Robust Protection". I do recall reading that however sorry my question was ambiguous...I guess I was more concerned about my EMS pin being connected directly to the starter cable. Should it have a 28 AWG fusible link or other protection?

>I do not know however if this protection extends to the radio or transponder and I am curious about that. So far I've always been keeping them off during engine start.

This is good information...I did not think of that.

I have two SV-1000 screens, two SV-BATTs, and two independent electrical systems each with its own battery and alternator. Each Display does not have an ON/OFF switch just a CB from the on side electrical bus. I plan on operating the two electrical systems completely isolated at all times in flight however during engine start I will have the bus tie closed so as to take advantage of the dual batteries.

The Pilot side bus powers its own display, the SV Radio, and the SV Autopilot (and servos).

The Copilot side bus powers its own display and all other ships electrical power.

I do have an avionics master switch so that after start I can turn on the Avionics master and then the GTN-650, SV-ADSB, and SV transponder will get powered so they are protected during start.

So in other words, The Pilot side electrical system will be powering the SV Radio and the SV Autopilot during start unless I pull their CBs.

Since I have two batteries I was not concerned about the electrical consumption of the SV Radio and Autopilot however now I am wondering about the post start electrical spike.

IS there "Robust Protection" for the SV Radio and Autopilot? I guess if SteveW has not burned up his gear I should be OK.

 

[swatson999]

Once again...

Any modern piece of avionics can handle whatever the system is throwing its way during startup. The fear of "spikes" is an OWT .

Go read this

http://www.aeroelectric.com/articles/avmaster.pdf

and you may wish to reconsider the hallowed Avionics Master.

However...when you say "EMS pin connected directly to the starter cable"...do you mean you've connected a pin to the big fat cable that runs from the starter contactor to the starter itself? That'd be....very bad. That line will see a VERY large current during starting, so that wire is going to go up in smoke tout de suite

 

[mrdaud]

Just a quick point, connecting a pin to the battery cable will not necessarily be an issue. If in series, yes, bad idea, but in a parallel circuit, not normally an issue. Ohm's law states that the current in a circuit is inversely proportional to the circuit resistance. In the case of a starter cable when starting, the current is maximum and the resistance is is very low. A parallel circuit, say a radio, has a higher resistance and will only see current flow base on that resistance. That is how birds can sit on high voltage wires and not get electrocuted. High resistance bird vs. low resistance wire. Just make sure the parallel line is breaker/fuse protected.

Also agree, most modern electronics will handle starting voltage spikes.

 

[swatson999]

Just a quick point, connecting a pin to the battery cable will not necessarily be an issue.  If in series, yes, bad idea, but in a parallel circuit, not normally an issue.  Ohm's law states that the current in a circuit is inversely proportional to the circuit resistance.  In the case of a starter cable when starting, the current is maximum and the resistance is is very low.  A parallel circuit, say a radio, has a higher resistance and will only see current flow base on that resistance.  That is how birds can sit on high voltage wires and not get electrocuted.  High resistance bird vs. low resistance wire.  Just make sure the parallel line is breaker/fuse protected.

Also agree, most modern electronics will handle starting voltage spikes.

Ah, yes...you are, of course, correct...I had an incorrect picture in mind when I read what was described. Thanks for the correction.

 

[mrdaud]

Steve, the worst time that happens to me is when my wife corrects me!

 

[Dynon101]

>...when you say "EMS pin connected directly to the starter cable"...do you mean you've connected a pin to the big fat cable that runs from the starter contactor to the starter itself? That'd be....very bad. That line will see a VERY large current during starting, so that wire is going to go up in smoke tout de suite

Yes. The output pole of the starter contactor is a 5/16 inch diameter copper threaded rod. One large 2 AWG cable goes to the starter motor and a second very small 26 AWG wire is the EMS wire.

The question is, does this small wire to the EMS need to have some kind of protection like a small 1 amp fuse or a 28 AWG wire run in series?

Thanks

 

[Raymo]

The question is, does this small wire to the EMS need to have some kind of protection like a small 1 amp fuse or a 28 AWG wire run in series?

Answered above...

"Just make sure the parallel line is breaker/fuse protected."