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  #11  
Old 01-07-2019, 05:00 AM
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mulde35d mulde35d is offline
 
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Default G3X system updates

That's an interesting idea I hadn't thought about it in regards to system updates. It would be too easy to run a parallel power wire from a dedicated hot CB/Switch to one of the many power inputs on the GTN 650 and GDU 460. It could normally be left open, and then turned on / closed to provide power for updates without having to touch the master. I like the idea, just have to locate it so it doesn't accidentally get flipped as it would essentially be its own hot bus. This is why I like sharing these things on this forum.
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  #12  
Old 01-07-2019, 05:08 AM
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Walt Walt is offline
 
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Quote:
Originally Posted by mulde35d View Post
That's an interesting idea I hadn't thought about it in regards to system updates. It would be too easy to run a parallel power wire from a dedicated hot CB/Switch to one of the many power inputs on the GTN 650 and GDU 460. It could normally be left open, and then turned on / closed to provide power for updates without having to touch the master. I like the idea, just have to locate it so it doesn't accidentally get flipped as it would essentially be its own hot bus. This is why I like sharing these things on this forum.
The G3X manual details backup battery inputs, pretty standard stuff.
The GTN power requirments are such that multiple HD pins are tied together, they are not meant to be used as seperate power inputs.
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  #13  
Old 01-07-2019, 06:12 AM
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mulde35d mulde35d is offline
 
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Good point Walt, forgot the HD pins can only handle about 3 amps each. Should still be simple enough to run a hot battery wire through a breaker/switch as if it were a backup battery. I am thinking locate it above the circuit breakers away from all other switches or next to the USB extension plug above the GDU460. I know I havenít posted a panel layout yet, but it is coming.
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  #14  
Old 01-07-2019, 06:15 AM
Southern Pete Southern Pete is offline
 
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Is a separate avionics bus required? If it is, consider 2 feeds as if either the switch or relay fails then all on that bus are lost.
Pete
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  #15  
Old 01-07-2019, 11:01 AM
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mulde35d mulde35d is offline
 
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Great question on the avionics bus. I used one primarily to protect the avionics during startup and provide a fast method of load shedding. However, based on what I have read, I don’t believe the Garmin products need the protection. Maybe a Garmin rep can pipe in on the topic.
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Last edited by mulde35d : 01-07-2019 at 11:03 AM.
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  #16  
Old 01-07-2019, 02:06 PM
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Quote:
Originally Posted by mulde35d View Post
Great question on the avionics bus. I used one primarily to protect the avionics during startup and provide a fast method of load shedding. However, based on what I have read, I donít believe the Garmin products need the protection. Maybe a Garmin rep can pipe in on the topic.
One of the main features with GAD27 is to have stabile power during startup, I now note that you have not connected those pins in your diagram. Check the G3X installation manual for what LRUs they suggest being on this "bus".
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  #17  
Old 01-21-2019, 09:16 AM
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mulde35d mulde35d is offline
 
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Default Garmin Support

I spoke with a Garmin rep this morning in regards to the GAD 27 "Keep Alive Power". He mentioned it is primarily designed for power throughput from a second battery / backup battery source to power critical components during engine start while the starter pulls off the main battery. Since I don't have a backup or second battery it would be pointless to run anything through those pins.

Also, he stated that none of the G3X suite or other modern Garmin products need the stable voltage during start. No damage will be done due to voltage changes. Now if the battery voltage from the main battery drops too low during start then they may turn-off / reset, but won't do any damage.

Your guys input is sending me down additional research paths. I like it, getting smarter every day. Thanks
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  #18  
Old 01-22-2019, 01:56 PM
n982sx n982sx is offline
 
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Quote:
Originally Posted by mulde35d View Post
I spoke with a Garmin rep this morning in regards to the GAD 27 "Keep Alive Power". He mentioned it is primarily designed for power throughput from a second battery / backup battery source ...
Was the Garmin rep one of the G3xperts? This doesn't sound right. Here is a blurb straight from Garmin.

Voltage Stabilizer for Consistent Power

For light aircraft that may not have a redundant power source, the GAD 27 adapter can be used as a voltage stabilizer to maintain a consistent power bus output of 12 V, preventing high-draw situations such as engine startup from dropping your avionics off-line. Your G3X Touch display stays lit, your engine monitoring reference stays powered up, and youíre able to maintain a stable, continuous power flow during momentary high current draw situations.


From memory, I believe it provides enough stabilizing current at 12v for the PFD, the engine monitor and the GAD 27 itself, which is all you need.

I have a GAD 27 installed but I also have a redundant power source. Never the less, I have the GAD 27 wired to the main bus per the above. It works fine if the aux bus is off during startup.
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  #19  
Old 01-22-2019, 02:32 PM
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Carl Froehlich Carl Froehlich is offline
 
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No matter what Garmin says, I would not crank the engine with power to the GTN-650. In my planes I do not crank the engine with any avionics on line.

You decide what you want to do.

Carl
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  #20  
Old 01-22-2019, 02:36 PM
rv7charlie rv7charlie is offline
 
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Many points of failure between B+ & avionics bus, and only one source of power.

Start circuit is unconventional; norm is to supply power to the start contactor coil from a 'fused' line through the switch, with the other end of the coil grounded.

Same with the avionics control circuit. Not saying it's wrong, but it's not the typical technique, and could cause a bit of confusion if a non-owner is trying to troubleshoot it.

You mentioned electrical noise, but it's difficult to see in the 'eye charts' what you're doing to mitigate it. You may well have dealt with it, but if not, be aware that most (nearly all?) noise issues are caused by ground issues. Where, what and how you ground matters a lot.

I'm another who has to disagree with Carl on the dual bat vs dual alt issue. I hear his argument, but dual bats doubles up on the most reliable accessory in the plane, and still results in finite (and variable with age) capacity. Alternators, on the other hand, have limited and very unpredictable lifespans. It's an even bigger issue with the current trend to electrically dependent engines, which often require quite a bit of electrical energy. Everyone should go with their (intelligently researched) comfort zone; mine is dual identical alternators (I have the luxury of mounting two).

Charlie
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