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  #1  
Old 10-12-2021, 10:35 PM
Marlonyoung's Avatar
Marlonyoung Marlonyoung is offline
 
Join Date: Sep 2021
Location: Santa Rosa, CA
Posts: 30
Default EXPBUS II - versus circuit breakers

I have acquired a RV4 project that has been stalled for a long time; for over 30 years I have own, maintained (with my I.A. father) and fly a C195 and Citabria.
This is my first foray into Experimental and building, so you might see post from me in the future.

I am just now getting into the electrical system, and it looks like they were planning on using an EXBUS II circuit board in the place of the battery relay (looks like they did plan on a starter relay/solenoid but they were using this circuit board with integrated toggle switchers as the master switch, battery relay and overvoltage protection circuit in leu of circuit breakers. Aircraft spruce does have the EXBUS II listed in their catalogue, but this is something I am completely unfamiliar with. Before just pulling it and replacing it with standard toggle switches and circuit breakers I thought I would reach out to see if anyone had used this system before or had experience with it.
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  #2  
Old 10-12-2021, 11:36 PM
Robert Sailor Robert Sailor is offline
 
Join Date: Nov 2018
Location: Nanaimo BC Canada
Posts: 147
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I have it in our 6 but I'm not that familiar with it other than it auto resets if it trips a circuit. I've put a few hundred hours on it and so far it's been trouble free.
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  #3  
Old 10-13-2021, 03:32 AM
74-07 74-07 is offline
 
Join Date: Dec 2016
Location: Greenville, SC
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Lots of them still installed. I have one in my 8 which works flawlessly but others have had some problems. The units are no longer manufactured or supported. The EXP II also limits your future options as it only has X number of each amp size breakers.

For those reasons, if I were building a plane today, I'd go with breakers. Seems you're at a point that you can go either way. If you decide to not use it, I'd be interested in buying it as a spare.
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  #4  
Old 10-13-2021, 05:19 AM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 862
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If you want electronic breakers, Vertical Power seems to be the one everybody is using these days.
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Last edited by Desert Rat : 10-13-2021 at 05:20 AM. Reason: typo
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  #5  
Old 10-13-2021, 05:30 AM
WingsOnWheels WingsOnWheels is offline
 
Join Date: Mar 2009
Location: Plano, TX
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If I were to build again, I would use a fuse panel for the majority of items and pullable breakers for the few critical systems that don't otherwise have an "off" switch. Such as: Trim, Flap Motor, Alternator Field, Autopilot, Starter Contactor.

The fuse panel allows for easy upgrades in the future and can be tucked away nicely.
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  #6  
Old 10-13-2021, 06:53 AM
BoydBirchler BoydBirchler is offline
 
Join Date: Jul 2020
Location: Indianapolis
Posts: 164
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I have 2 EXP-buss boards remoted. One board for the avionics and one for the rest of the electrical system. Works as intended and costs 1/5th of what a Vertical Power system costs.
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  #7  
Old 10-13-2021, 11:10 AM
jclark jclark is offline
 
Join Date: Jan 2005
Location: Columbia, SC
Posts: 890
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Quote:
Originally Posted by 74-07 View Post
Lots of them still installed. I have one in my 8 which works flawlessly but others have had some problems. The units are no longer manufactured or supported. The EXP II also limits your future options as it only has X number of each amp size breakers.

For those reasons, if I were building a plane today, I'd go with breakers. Seems you're at a point that you can go either way. If you decide to not use it, I'd be interested in buying it as a spare.
I have had one installed in my RV6 since 2002. The plane was featured at the Control Vision booth at Oshkosh in 2003. Worked with no issues (other than the time when my leaking tip-up allowed it to get filled with water!!). I was able to wire it with AUX BUSS and BBAT (backup battery) charging.

[Later, for a total rewire on the RV8, I went with FUSE BLOCKS as I wanted a LOT more items protected.]

If it covers everything you would imagine for your mission, it works just fine. For new installations with a LOT MORE electronics these days, especially an IFR setup, I would take a different path. My personal preference just happens to be fuse blocks.
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  #8  
Old 10-13-2021, 11:27 AM
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Dan 57 Dan 57 is offline
 
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Location: LSZF
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Quote:
Works as intended and costs 1/5th of what a Vertical Power system costs.
Same here… installed one a few years ago in a previous aircraft of mine, and to this day works perfect. Installation was easy, and the physical size small.
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  #9  
Old 10-13-2021, 01:08 PM
n816kc n816kc is offline
 
Join Date: Jan 2005
Location: Winter Haven, FL
Posts: 289
Default Worked great, until it didn’t

Had one in my -6. Worked just fine for 10 years and then one day it didn’t. Replaced it with switches and fuse blocks. Agree with the limitations noted above. Doing it again I’d go with fuses or breakers.
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Last edited by n816kc : 10-13-2021 at 01:11 PM.
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  #10  
Old 10-13-2021, 09:21 PM
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Marlonyoung Marlonyoung is offline
 
Join Date: Sep 2021
Location: Santa Rosa, CA
Posts: 30
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Thanks for the info - since they have it wired in (put sitting for 10 years) I will probably try to power it up and see if it still works. I have very little need for electrical (basic VFR only) so redoing would not be significant, but then this may be adequate. Decisions!
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