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  #1  
Old 12-07-2013, 12:49 PM
dekky111 dekky111 is offline
 
Join Date: Aug 2005
Location: Grand Rapids, MI
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Unhappy 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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  #2  
Old 12-07-2013, 08:56 PM
sailvi767 sailvi767 is offline
 
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Location: Charlotte NC
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You might check your alternator belt tension. A slipping belt can cause strange readings.
George
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  #3  
Old 12-07-2013, 08:59 PM
KBSUP KBSUP is offline
 
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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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  #4  
Old 12-08-2013, 06:12 AM
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rzbill rzbill is offline
 
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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.
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  #5  
Old 12-08-2013, 06:31 AM
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Rhino889 Rhino889 is offline
 
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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?
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  #6  
Old 12-08-2013, 06:44 AM
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Walt Walt is online now
 
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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.
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Last edited by Walt : 12-08-2013 at 06:53 AM.
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  #7  
Old 12-08-2013, 07:24 AM
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Rhino889 Rhino889 is offline
 
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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
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  #8  
Old 12-08-2013, 08:45 AM
BillL BillL is online now
 
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Quote:
Originally Posted by rzbill View Post
Check the bus voltage sense line between the bus and the LR3. An intermittent break in that line will cause the symptoms described.
+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.
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  #9  
Old 12-08-2013, 01:03 PM
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C-FAH Q C-FAH Q is offline
 
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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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  #10  
Old 12-08-2013, 02:40 PM
dekky111 dekky111 is offline
 
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Default Appreciated

Thanks for all your replies: 18 degrees in the hangar right now. Will get to work on it tomorrow
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