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12-07-2013, 12:49 PM
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Join Date: Aug 2005
Location: Grand Rapids, MI
Posts: 107
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Ammeter/Voltage spikes
RV7-A with 40A alternator, LR-3 controller, Odyssey PC680 battery.
Have been noting amperage spikes to 25-35a that are intermittent. Today noted EIS voltage spikes to 15.2 V. Normally runs ~ 14.6V at cruise. Am I looking at a battery or regulator problem? Any guesses?
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12-07-2013, 08:56 PM
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Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,167
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You might check your alternator belt tension. A slipping belt can cause strange readings.
George
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12-07-2013, 08:59 PM
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Join Date: Sep 2011
Location: Calhoun, GA
Posts: 9
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Spikes
Could be regulator high temp. Got the same problem and looking to run cooling scat tube to the regulator and see if that fixes the problem.
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12-08-2013, 06:12 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Check the bus voltage sense line between the bus and the LR3. An intermittent break in that line will cause the symptoms described.
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
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12-08-2013, 06:31 AM
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Join Date: Dec 2009
Location: Jupiter FL.
Posts: 451
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I'm having similar issues.
http://www.vansairforce.com/communit...d.php?t=107239
Do you have a blast tube pointed at the regulator? I do not. I read it doesn't matter... But now I'm thinking it does if you run hard. If someone says they haven't needed one in 700hrs. Then they state they like to fly at 150kts saving fuel... Different sorry on my plane! I fly 185kts+ everywhere.
Replacing alternator and directing blast tube Monday. (We'll see?)
Does your amps drop to zero or negative before the spikes? If the alternator is cutting out and ships power comes from the battery. Battery draws down then the alternator jumps back on line and jolts the battery with some juice?
__________________
VAF DUES 7/13, 12/13, 03/14
Founder/Director
www.Aircraftwraps.com
Replace paint with performance.
This is my personal account and does not reflect the official communications of Aircraftwraps.com. We have retained a username for such correspondence. I post about formation, eating, aerobatics and pilot stuff  .
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12-08-2013, 06:44 AM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,687
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Small voltage fluctuations above 14-15v (although not normal with the B&C alt/regulator) would not cause large amperage swings on it own. Large amperage swings can be caused as noted above if the alternator is dropping off line then coming back on and re-charging the battery (not what you described), a short or bad battery.
Of course verifying indications and all connections are secure (not sure what you have for a V/A meter) would be the first thing.
__________________
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
Last edited by Walt : 12-08-2013 at 06:53 AM.
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12-08-2013, 07:24 AM
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Join Date: Dec 2009
Location: Jupiter FL.
Posts: 451
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Walt,
Thanks for posting. Your statement about that battery just made a lightbulb go off in my head! Gonna switch out the battery today before messing with the alternator.
Thanks again,
Scott
__________________
VAF DUES 7/13, 12/13, 03/14
Founder/Director
www.Aircraftwraps.com
Replace paint with performance.
This is my personal account and does not reflect the official communications of Aircraftwraps.com. We have retained a username for such correspondence. I post about formation, eating, aerobatics and pilot stuff  .
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12-08-2013, 08:45 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by rzbill
Check the bus voltage sense line between the bus and the LR3. An intermittent break in that line will cause the symptoms described.
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+1, And . . the other side of that is the ground. Be sure grounds are secure out to the alternator too. Think how your voltage is measured and how the alternator senses it. Your wiring diagram and knowing your specific connection will help greatly.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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12-08-2013, 01:03 PM
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Join Date: Dec 2008
Location: Ontario, Canada
Posts: 464
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Spikes
I had exactly the same issues last year. The molex plug that goes into the alternator had a loose pin. Fixed that and supported the wire better and have not had a issue since.
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12-08-2013, 02:40 PM
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Join Date: Aug 2005
Location: Grand Rapids, MI
Posts: 107
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Appreciated
Thanks for all your replies: 18 degrees in the hangar right now. Will get to work on it tomorrow 
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