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Vertical Power and E-buss

R

RandyAB

Well Known Member
I'm struggling with designing the most efficient way of integrating a Vertical Power Pro with an ebuss for backup. I'm not sure if I'm missing something and would appreciate kind input to get me on the right track.

Firstly, my system is going to have dual alternators and dual batteries. The SDS system is going to be wire on it's own buss, independent of Vertical Power with the avionics powered mainly through the VP, divided between the two busses that the VP Pro offers. I'd like to backup my critical avionics via a separate ebuss. I've studied backup method B and C in the VP install manual. What I don't like about these methods is that they seem to demand a switch for each piece of backup equipment. I'd prefer to be able to just power the ebuss with one backup switch and eliminate the others if possible. One solution that I'm looking at is using a Power Deuce Schottky like this one and feeding power in by both the ebuss and the VP.

http://www.periheliondesign.com/powerschottkydiodes.htm

Is this an acceptable solution? Is there one that is simpler that I am overlooking? Perhaps I am overthinking. Helpful advice is appreciated. Preemptively, I am most of the way through Nuckoll's book and have been once through Ausman's book as well.
 
I might take some abuse for saying this, but do you really, really want a VPX? You have a dual redundant system, but are planning on sending all your electrics through the VPX. That makes no sense to me, even with an e-bus you will end up duplicating much of the VPX that makes it not really worthwhile. What benefits do you get from the VPX?

With dual alternators and batteries you have decided you need the redundancy of 2 separate generating systems, that can provide redundant power supplies to the SDS. Provide 2 power inputs to the SDS in case one quits. How feed one busbar from both sources with a diode on each feed to prevent one bus back feeding the other. Now hang fuses from the bus to power your services. The alternator with the highest voltage will power the supplies (assuming it has the power to do so).

Write a list of what the VPX gives you and how to achieve those features without it and determine the value it is providing to your system. If it is worthwhile connect it to the bus described above; if it fails you will not lose the engine or critical avionics.
Pete
 
RandyAB said:
I'm struggling with designing the most efficient way of integrating a Vertical Power Pro with an ebuss for backup. I'm not sure if I'm missing something and would appreciate kind input to get me on the right track.

Firstly, my system is going to have dual alternators and dual batteries. The SDS system is going to be wire on it's own buss, independent of Vertical Power with the avionics powered mainly through the VP, divided between the two busses that the VP Pro offers. I'd like to backup my critical avionics via a separate ebuss. I've studied backup method B and C in the VP install manual. What I don't like about these methods is that they seem to demand a switch for each piece of backup equipment. I'd prefer to be able to just power the ebuss with one backup switch and eliminate the others if possible. One solution that I'm looking at is using a Power Deuce Schottky like this one and feeding power in by both the ebuss and the VP.

http://www.periheliondesign.com/powerschottkydiodes.htm

Is this an acceptable solution? Is there one that is simpler that I am overlooking? Perhaps I am overthinking. Helpful advice is appreciated. Preemptively, I am most of the way through Nuckoll's book and have been once through Ausman's book as well.
Click to expand...

I have a VPX/Pro, two batteries, and two alternators. I have a pair of switch/contactor that can isolate or join each battery to the main buss. I use the diode in your link to ensure that the ebus battery is charged when isolated. It's more or less a combination of the two backup methods in the manual.

You're still stuck with adding more switches. Many devices, such as the Garmin GTN650, don't have a back up power input. You'll need a switch to move the power source from the main bus to the ebus.

I've been flying for over five years and haven't had an issue arise that this configuration wasn't able to handle.
 
Southern Pete said:
I might take some abuse for saying this, but do you really, really want a VPX? You have a dual redundant system, but are planning on sending all your electrics through the VPX. That makes no sense to me, even with an e-bus you will end up duplicating much of the VPX that makes it not really worthwhile. What benefits do you get from the VPX?

With dual alternators and batteries you have decided you need the redundancy of 2 separate generating systems, that can provide redundant power supplies to the SDS. Provide 2 power inputs to the SDS in case one quits. How feed one busbar from both sources with a diode on each feed to prevent one bus back feeding the other. Now hang fuses from the bus to power your services. The alternator with the highest voltage will power the supplies (assuming it has the power to do so).

Write a list of what the VPX gives you and how to achieve those features without it and determine the value it is providing to your system. If it is worthwhile connect it to the bus described above; if it fails you will not lose the engine or critical avionics.
Pete
Click to expand...

Thank you Peter for your input. I appreciate it. I really do like the functionality of the VPX system overall. From what I've read, the dual independant busses of the VPX Pro with the ability to provide backup power input is inherently a safe design that should make an emergency a very unlikely event. I will dwell a bit more on what you've suggested. Thank you.
 
rleffler said:
I have a VPX/Pro, two batteries, and two alternators. I have a pair of switch/contactor that can isolate or join each battery to the main buss. I use the diode in your link to ensure that the ebus battery is charged when isolated. It's more or less a combination of the two backup methods in the manual.

You're still stuck with adding more switches. Many devices, such as the Garmin GTN650, don't have a back up power input. You'll need a switch to move the power source from the main bus to the ebus.

I've been flying for over five years and haven't had an issue arise that this configuration wasn't able to handle.
Click to expand...


Thank you Bob for your very helpful comments. The GTN 650 that I plan to use as you did really presented the greatest challenge because of the lack of dual power inputs. I wasn't completely sure that the diodes that I referenced were the correct way to approach the problem. I'm very glad that that you have experience with them and that you utilized them as I am considering. I will draw out a main power distribution plan and post it once I've had a chance to do so. Perhaps at that point you could offer an opinion as to whether what I've come up with is as good as your system and offer a critique at that point. Thanks again.
 
Email me

Randy - send me an email at cjd9 @ me . com and I can send you my schematic if you would like. I am doing a very similar thing.
 
rleffler said:
Many devices, such as the Garmin GTN650, don't have a back up power input. You'll need a switch to move the power source from the main bus to the ebus.
Click to expand...

The GTN650 does have dual power feed. In fact it has 6 power feeds since the GPS/Comm/Nav all have separate dual feeds. Connector P1001 pins 19 and 20, connector P1003 pins 43 and 44, and connector P1004 pins 51 and 52 are all power and backup power connection pairs. I asked Garmin if I should feed all 6 connections separately. They told me most installers hook them up 3 and 3 to two separate power feeds.

I have a VPX in my system with an e-buss. It only added one extra switch to select the e-buss. I feed a small, e-buss blade fuse box, direct from the battery with a 15 amp resetable breaker. This bypasses the master as well as the VPX. Here is a thread with details on my system http://www.vansairforce.com/community/showthread.php?t=152279
 
Last edited:
I'm very similar, planning a switch to a second, isolated battery that powers the engine bus and IFD 440 and PFD (with ems). The battery remains charged through a diode.

I can kill the entire system with the master then flip the "oh ****" switch which then brings the second battery online and restores everything needed to run the engine.

I don't see a need for two VPXs. There is a point where a system just gets too complex. VPX advises not to run an engine system through it anyway. My engine bus is powered from the PPS with a separate power wire going to the VPX for all the other stuff.
 
leok said:
The GTN650 does have dual power feed. In fact it has 6 power feeds since the GPS/Comm/Nav all have separate dual feeds. Connector P1001 pins 19 and 20, connector P1003 pins 43 and 44, and connector P1004 pins 51 and 52 are all power and backup power connection pairs. I asked Garmin if I should feed all 6 connections separately. They told me most installers hook them up 3 and 3 to two separate power feeds.

SNIP
Click to expand...

This is interesting. I just looked at the install manual again and while there are separate pins for power as you discribe, my impression was these are not separate feeds, just smaller wires in parallel to handle the higher current (page D-8 of the install manual is example).

Are you confident that the GTN-650 has independent power input capability?

Carl
 
leok said:
The GTN650 does have dual power feed. In fact it has 6 power feeds since the GPS/Comm/Nav all have separate dual feeds. Connector P1001 pins 19 and 20, connector P1003 pins 43 and 44, and connector P1004 pins 51 and 52 are all power and backup power connection pairs. I asked Garmin if I should feed all 6 connections separately. They told me most installers hook them up 3 and 3 to two separate power feeds.

I have a VPX in my system with an e-buss. It only added one extra switch to select the e-buss. I feed a small, e-buss blade fuse box, direct from the battery with a 15 amp resetable breaker. This bypasses the master as well as the VPX. Here is a thread with details on my system http://www.vansairforce.com/community/showthread.php?t=152279
Click to expand...

Thanks for the info Leo. I'm reading conflicting bits on this which has added to the confusion. Do all of the components that you chose for the ebuss have dual power input capability? If so, that simplifies things for me since I think I'm going to be running the same components. Can I ask what B/U alternator you chose? The B&C gear driven secondary alternator that I was quoted on by Aerosport looks like it only puts out about 20 amps when used with the 540 so I was looking for an alternative with a bit more juice.
 
Carl,

I specifically asked the Garmin folks at their G3X installation seminar at Oshkosh last year about the 6 power pins of the GTN650. It was a challenge to have 6 independent power feeds (even though I had already done it this way). I was told they were generally connected 3 and 3, primary and back up, by most installers. As I understand the system, they are isolated by diode interconnects inside the GTN650 to pull power from whichever line is live.

Randy,

All of the equipment I chose for the e-buss has the dual power feed capability (all Garmin in my case). However, it wouldn't be that difficult to set your own diode isolation for dual power feeds outside of any particular box. Just add a properly rated diode to the end of each power feed where they connect to the power in pin.
I plan on having a PP 60 amp main and PP 20-30 back up alternator. I have my avionics set up with avionics 1, 2 and 3 switches so I can depower in groups if I ever need to. 3 are the most expendable, 2 the next tier, 1 are critical to continued flight and my e-buss is for the loss of my master solenoid and/or longest duration critical to get on the ground instruments. The VPX makes the three tier system easy and flexible since I can assign outputs to any switch (avionics 1,2 and 3) and readjust if I need to.

I'm not saying this is right or wrong, just what my thinking through possibilities led me to. I am always willing and ready to learn from others.
 
I've never heard that the multiple power pins on the 650 can be used as "back up" power source.
From the manual:

"For power and ground, use the wire gauge specified in the interconnect
drawing in appendix E, then 22 AWG for the short length from the splice to the connector."
 
I'm with Walt on the 650 power pins. The reason for the multiple pins is to supply ample current with the smaller gauge wire for the high density db connector pins.
 
Walt, based on your comment I went back through the GTN650 Installation Manual and called Garmin for additional clarification. In short you are correct that the dual power pin connections in the GTN650 are not for main and backup power.

The power distribution diagrams in section 2.4.7.x as well as the typical interconnect diagram E-2 show connector P1001, pins 19 and 20 and connector P1004 pins 51 and 52 all connected to a single 7.5 amp breaker. This feeds the GPS and Nav radios. The com radio is powered by connector P1003 pins 30, 43 and 44 all connected to a single 10A breaker. When I asked the Garmin tech if the pins could be connected as main and back up power the tech said only that he would recommend sticking to the E-2 diagram ... ok good enough for me, I stand corrected.

When I asked why sets of 2 or 3 pins times 3 are required to power the GTN650 the tech could not give me an answer and transferred me to the "experimental guys" who unfortunately did not answer. (I'm not sure why when the GTN650 is a certified product)

So now I have some adjustments to make on my current GTN650 wiring and diagram as well as a little homework to do. I absolutely remember reading the install manual on other Garmin components that indicated the pair of power pins was for primary and back up power feeds. I now need to confirm which ones and make sure I don't have any other errors.

I still see no reason why I could not use external diodes to accomplish the same dual feed without back feeding the unused power wire. The good part of this is that it will free up a few VPX outputs for other things.
 
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