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01-08-2015, 08:37 AM
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Join Date: Jul 2007
Location: Taylorsville, Ga
Posts: 798
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The OV protection is certanily a plus in those Alt like Plane Power and B&C which provide that protection. Appears that externally regulated alts may be easier to "add" that on. Looks like the site in post from Don might be an option but also needs a contactor, 5amp supply and some wire. would be nice to see that device incorporate the "contactor" and feed the B+ directly. That should be doable with today's electronics.
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DRRhodes
2020 VAF Supporter
RV9 N908DR
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01-08-2015, 12:24 PM
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Join Date: Aug 2005
Posts: 36
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B+ not just Field.
The OV failure mode in internally regulated auto alternators can be "self exciting" which, despite what you think, means that disconnecting the field isn't enough, you have to disconnect the current feed from the alternator(B+) also. So if you're using an internally regulated auto alternator(al la Vans standard) the OVP protection should include running the B+ through a contactor, the contactor should be powered by the field lead.
When the OV event happens, the crowbar pops the field breaker, the B+ contactor opens and the faulty alternator is completely isolated.
See page 2 here:
http://www.aeroelectric.com/DIY/DIY_Crowbar_OVP_F.pdf
Along with the warning not to use internally regulated alternators...
Electronics don't like heat... if you put the regulator behind the firewall you get to run 1000+ hrs with no alternator failures like me... I went through 2 automotive alternators in less than 100 hrs before I bucked up and got a B&C alternator...
Bill Judge
N84WJ, RV-8, 1100 hrs
RV-8.blogspot.com
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01-08-2015, 05:06 PM
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Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,567
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Why not just put the crowbar on the B+ CB or ANR?
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Actual repeat offender.
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01-08-2015, 05:25 PM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
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Quote:
Originally Posted by aerhed
Why not just put the crowbar on the B+ CB or ANR?
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The crow bar would likely go up in flames before the main CB or ANR blew 
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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01-08-2015, 08:14 PM
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Join Date: Jan 2013
Location: Spruce Creek Fly-In FL.---Stratham N.H.
Posts: 20
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buy a 40amp DENSO alternator for 2000hrs trouble free operation----John
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you can NOT TEACH experience-----you must acquire it--- RV-8 (first flight 1998)
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01-09-2015, 09:10 AM
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Join Date: Jul 2007
Location: Taylorsville, Ga
Posts: 798
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Quote:
Originally Posted by Sky Goddess
buy a 40amp DENSO alternator for 2000hrs trouble free operation----John
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Actually that is what i ve been running since 2008. Good performance with No problem.
__________________
DRRhodes
2020 VAF Supporter
RV9 N908DR
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01-09-2015, 09:50 AM
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Join Date: Mar 2008
Location: Seattle
Posts: 1,412
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The bulged Odyssey battery failed over time. It controlled the alternator's over voltage condition until it was over charged to the point it built up excess pressure and heat.
All the while, it was holding the system voltage down. I don't know how high the voltage initially went, but probably not enough to ruin modern dual voltage avionics.
Install a properly sized circuit breaker that can be manually opened on the alternator output wire. It would trip if the alternator 'went wild'. also, adding an over voltage alarm would inform the operator to manually open the circuit breaker.
Additionally, if you needed a bit more electricity to make it to the closest runway, the operator might briefly close the breaker to jolt some juice into the battery, then re-open the breaker?
__________________
Scott Emery
http://gallery.eaa326.org/v/members/semery/
EAA 668340, chapter 326 & IAC chapter 67
RV-8 N89SE first flight 12/26/2013
Yak55M, and the wife has an RV-4
There is nothing-absolute nothing-half so much worth doing as simply messing around with Aeroplanes
(with apologies to Ratty)
2019
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01-09-2015, 07:07 PM
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Join Date: Jan 2010
Location: Tybee Island, GA
Posts: 664
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Battery fAiled
The reason that battery looks that way: Ironically the battery sarted failing as we were approaching a paper pulp plant and a water plant which smells as bad as sulfuric acid! The sulfuric smell from the battery got worse and worse and we both thought it was the air outside! The EFIS never gave the PIC a warning and if it did, it got intepreted as something else. the engine parameter page was in minimized mode and the OV was not noted. See the trend here?
im glad we were close by our home airport. I was riding in the back close to the battery installation and my chest was on fire for a couple of days after! If that battery had caught on fire im sure there was nothing I could have done to extinguish it!
Few operational changes are in place now.
__________________
Mitch V.
Semi-Retired in Tybee Island GA
2007 MX2 Nigel Lamb EX RBAR MX2 (Current)
2020 MX2 New Kit Position (Sold at OSH to Team RV Member)
2009 Team Rocket F1 (Sold)
2008 MXS Green Slime"(Sold)
2007 MX2 Patches" (Sold)
1999 Giles 202 "Primal Fear/Perucho" (Sold)
1965 PA32-260 "God Bless America" (Sold)
2003 RV6 "Airhawk One" (Sold)
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