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  #1  
Old 03-23-2021, 11:47 AM
Bassman Bassman is offline
 
Join Date: Feb 2021
Location: Covington, TN
Posts: 5
Default External 12V DC Bypass Battery?

Lots of posts on the addition of 12v external power source. Most say bypass the battery and master switch. Why is this if the input power from the external (battery) is equal to or greater than the voltage on the airplane's battery? is there a chance of damage to the system? In addition to battery charging, I'd like to fire up my Dynons and do some hangar flying since I'm new to these avionics.

I'm running an Odyssey 12v primary and backup on my RV7A..

Thanks
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  #2  
Old 03-23-2021, 12:41 PM
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rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGY
Posts: 3,755
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I think the main concern is when someone hooks up a battery charger to run their electronics, since they do some interesting things to de-sulfate and charge the battery.

If I planned to run my electronics in the hanger for more than an hour or so, I'd just disconnect the battery and hook up a good quality 14v power source. No chance of damaging the battery or the electronics.

If you take it in intervals that your battery can support, just run off the battery for a while, then take a break after turning off the electronics, and hook up the battery charger.
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  #3  
Old 03-23-2021, 02:44 PM
Tcheairs Tcheairs is offline
 
Join Date: Feb 2021
Location: Covington
Posts: 43
Default Hangar Flying Avionics

Makes sense..use the battery and then re charge it. I only need to run a Dynon 180 EFIS and the EMS 100. will turn everything else off. But I would like to install a pigtail so that I don't have to re string all of the piano hinges.
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  #4  
Old 03-23-2021, 05:33 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,171
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Quote:
is there a chance of damage to the system?
There is a big chance of damaging avionics if battery polarity is reversed.
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  #5  
Old 03-23-2021, 05:46 PM
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Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 2,951
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Just wire a pigtail, with a “shore power breaker” to your master buss. You decide if you want it to just power the plane (as in you keep the master off) or you power the plane and charge the battery at the same time (master on). The later is what I do. A standard $100 30 amp regulated switching power will do everything you need.

If you have an abused battery (you ran it flat) first address that. The recovery from most abused batteries is to just replace it so you have some confidence on battery capacity.

Carl
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  #6  
Old 03-28-2021, 04:57 AM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 1,103
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I have one of these (15v version) trimmed to 14.4v.
https://www.meanwell.com/webapp/prod...x?prod=HRP-600
I have a pigtail from the bus with an XLR socket on the end.
If I don't need much current I use the aux (cigarette lighter) as an input.
If I switch the master on the battery will be charged.

Pete
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  #7  
Old 03-28-2021, 01:22 PM
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rv8ch rv8ch is offline
 
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Quote:
Originally Posted by penguin View Post
... If I don't need much current I use the aux (cigarette lighter) as an input.
If I switch the master on the battery will be charged. ...
Never even thought of that - you are plugging it into the consumer side of the battery contactor and it powers everything up. Great tip, Pete!
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