912IS with VPX - Wiring question

[tracstarr]

I'm finally getting started on making all my wiring connections. I've run into a few questions though so this is for those who have a 912IS with a VPX. I know there are a few out there.

1) Did you bother with the alternator field connection? I'm leaning towards not doing it since it adds a mechanical point of failure

The 912Is install manual, for lack of better wording, sucks - especially with the electrical portion. I'm trying to figure out a few things here (looking at figure 3.14)
2) The HIC connectors provide two pins for starter button/switch. How did you integrate this with the VPX starter PIN?
3) The fuse box connector, X3 shows pin 3 and pin 1 having a 30A breaker on the engine side. Has anyone actually put it on the engine side? I know of two people who didn't. Also, what kind of breaker did you use? If my understanding is correct, the two fuses are guarding the fusebox (well, whatever the X3 connects to inside it) ?
4) Switches S2 and S3 are SPDT. Can they be combined into a DPDT? (ON) -OFF-ON ?

These are more specific to Garmin G3 and 912is
5) has anyone connected the lane A/B warning lamps to discrete in PINs to the G3X as well?

6) Where do you install the shunt? As in which side of the firewall?

[Shadowrider]

I need to read closer your questions but a quick answer to the one I know. You don’t need a shunt. VPX knows what power comes in and what power comes out so you don’t need a shunt. I used a breaker switch for the feed from voltage regulator vpx. Look closely at vpx install manual as they show how to incorporate the starter to the vpx. It then sends a start annunciator to G3X when the button is pressed.

[JoeRuscito]

Me personally I kept the engine separate of VPX when it came to alternator field or starter annunciations.

I use two simple breakers for the two 30 amp breakers.


Sent from my iPhone using Tapatalk

[tracstarr]

I need to read closer your questions but a quick answer to the one I know. You don’t need a shunt. VPX knows what power comes in and what power comes out so you don’t need a shunt. I used a breaker switch for the feed from voltage regulator vpx. Look closely at vpx install manual as they show how to incorporate the starter to the vpx. It then sends a start annunciator to G3X when the button is pressed.

Yeah, I think the only advantage of the shunt is being able to see charging voltage.

They do show how to include the starter, but not specific to the 912IS as it has specific starter connections in the HIC. I was told by vpx staff "For the starter…the J10-1 output just runs to the switch, and then from there it is wiring per Rotax, so the HIC connections would be on the other side of the starter switch, I believe. There are a bunch of Rotax powered airplanes out there running VP-X, and I’m pretty sure from the switch on, it’s all per Rotax." But that doesn't make sense to me. This would mean there are two wires going to starter? One from rotax HIC and one from VPX?
Maybe that's ok?

[tracstarr]

Me personally I kept the engine separate of VPX when it came to alternator field or starter annunciations.

I use two simple breakers for the two 30 amp breakers.


Sent from my iPhone using Tapatalk

Are the breakerss on your dash or hidden?

[efwd]

I wired the engine as per the 912iS FWF instructions from Kitfox. I used fuses that are hidden. My VPX is not connected to the engine. No shunt.

[JoeRuscito]

Hidden under dash.


Sorry for the short answers, been traveling and training with Stick and Rudder!

From my understanding the starter features in the VPX give you indication when the starter is engaged but also work to disable the starter once the motor is running in case the button is accidentally pushed. I did not feel comfortable breaking into the Rotax system as designed because I want sure if it would cause the computer to think there was a problem. Those features were not important to me.

As everyone has said, no need for a shunt the VPX senses current as well as bus voltage and the 912is can also output lane a and lane b voltages via Fadec/canbus ands output to the G3X.

I had two hidden fuses, one I believe protects the start power circuit and the other protects the charging circuit (correct me if Im wrong here). I used 30 amp for both as spec'ed by Rotax, I believe kitfox calls for one to be lesser rating.

I personally would keep your lane indicator lights outside of G3X, for what ever reason your screen dies you still get some engine info if there's an issue.

Another VPX note. They call for diodes on the starter and main contactor. Because you have little info as to what is included in the rotax circuitry I was hesitant to put this in, in case it would conflict or double up on existing circuits. I called kitfox and they said they do not put one on the starter, only the main.

Hope that helps!

[Shadowrider]

Joe has got you all squared away. Only thing I would add is I think I would prefer to have your lane A and B on the G3x instead. You can setup an alert that will give you a CAS message along with audio alert. If you want both you could also do that also I suppose. I prefer more of the clean panel look and like incorporating everything into the G3x that I can.

[tracstarr]

That's for all the info/tips. I think I have it all squared away on paper right now.

I currently plan on having the lane a/b and low fuel warning wire to both the g3x and an external light. These were what I decided were most important to see.This way I have two sources and if I lost the g3x screen I would still have indicators. All other warnings I'm running just through the g3x.

I'm going to clarify the use of the diodes for the vpx. I'm guessing something to do with only having the vpx see a voltage over a certain amount. I'm guessing the starter/master might leak a little? Just a guess.

I guess its more purchases from aircraftspruce for the breakers. Will skip the shunt.

I wish there was cheaper/free shipping with AS. It seems every time I make an order I need to make another. Ugh.

Hope to get things all wired up within the next week. (so really... probably 2-3).

[efwd]

Just go to your auto supply store and pick up a fuse block. Marine shops are great too. Fuses are inexpensive.

[tracstarr]

I meant to say Thanks all, not That's all.