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  #1  
Old 12-07-2018, 12:44 AM
az_gila's Avatar
az_gila az_gila is offline
 
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Question Load shedding with boxes using back-up batteries

I'm doing some forward planning with my VPX system but the answers may also apply to AeroElectric Main/Endurance bus users.

I just found out that you can't 'make' a Dynon Skyview system go into "back-up battery mode" without switching off it's 12v source. So if you want to conserve main battery capacity in an emergency you need a separate power switch. The unit will only go into internal battery mode when it loses it's power source.

This makes a difference if you are using the VPX Back-Up METHOD B from their manual. You need a "load shedding" switch on the panel for the Skyviews, preferable one with a safety switch cover.

These switches would help load management if the electrical system or VPX unit goes belly-up.

Besides helping others planning on VPX units, I am wondering if this "no manual method of going to back-up" is prevalent for other units such as the Garmin G5 I'm planning on and should be accounted for.

Please no "don't use a VPX" responses...
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  #2  
Old 12-07-2018, 08:18 AM
219PB 219PB is offline
 
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Gil,

I have the VPX set up on my system with two EFIS. Did not install a backup power for them because I installed the Dynon backup batteries. I figured that if the VPX did go "belly up" that it would stop supplying power to the EFIS. The Dynon backup up automatically kick in then. If I needed to load shed because of a battery or alternator problem, I would shut the power off using the VPX screen on the Dynon. My reliability model did not include multiple failures, such as concurrent alternator and VPX failures.
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  #3  
Old 12-07-2018, 08:32 AM
jwilbur jwilbur is offline
 
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Quote:
Originally Posted by 219PB View Post
Gil,

I have the VPX set up on my system with two EFIS. Did not install a backup power for them because I installed the Dynon backup batteries. I figured that if the VPX did go "belly up" that it would stop supplying power to the EFIS. The Dynon backup up automatically kick in then. If I needed to load shed because of a battery or alternator problem, I would shut the power off using the VPX screen on the Dynon. My reliability model did not include multiple failures, such as concurrent alternator and VPX failures.
Same here. To account for partial VPX failure such as only one bank going south, I have judiciously assigned components. For example, each Dynon screen is on a different power bank.
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  #4  
Old 12-07-2018, 09:10 AM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by az_gila View Post

Please no "don't use a VPX" responses...
Wow - talk about testing one’s restraint....

Carl
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  #5  
Old 12-07-2018, 09:17 AM
rocketman1988 rocketman1988 is offline
 
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Default Good on you!

Gil,

Good on you for adding your qualifying remark about "not using the VPX".

There are SOOOOO many people on these boards that believe their way is the ONLY way...
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  #6  
Old 12-07-2018, 11:46 AM
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majuro15 majuro15 is offline
 
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Could you achieve your desired results with an avionics master switch? That's what I had planned for when doing VPX (I'm now using the ACM from AFS, but nearly the same thing). You could put the PFD, EMS, Comm 1, Nav 1, GPS on the Master and then assign all other electronics to Avionics Master. One switch and you killed anything extra. For that matter, you could simply choose to put the G5 and a gps/comm on the Master then have everything else on the avionics master although start up might be a challenge.
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  #7  
Old 12-07-2018, 12:13 PM
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az_gila az_gila is offline
 
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Quote:
Originally Posted by majuro15 View Post
Could you achieve your desired results with an avionics master switch? That's what I had planned for when doing VPX (I'm now using the ACM from AFS, but nearly the same thing). You could put the PFD, EMS, Comm 1, Nav 1, GPS on the Master and then assign all other electronics to Avionics Master. One switch and you killed anything extra. For that matter, you could simply choose to put the G5 and a gps/comm on the Master then have everything else on the avionics master although start up might be a challenge.
Thanks.... I'll have to think about that a little more.

It's an interesting re-defining of the VPX switch functions.
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