T

texdog

Well Known Member
New alternator, internally regulated and works great as long as it has a load. About 2 hours into a flight if the lights are all off and the only load is the Garmin 696, the EFIS and two MFDs the amps will go to zero and the oil pressure indication will go low and the oil temp will go up. As soon as you turn the strobes or nav lights on everything returns to normal. I have no idea why the load makes a difference. I am very electrically challenged. This has happened with 3 different alternators. Any ideas from the brain trust would be appreciated.
 
Sure sounds like a bad connection on the field supply wire. The amp demand has to be high enough to make a connection. One might just run a jumper and replace the whole path from power to the alternator to be sure.
 
Alternator

Voltage is 14.3 more or less all the time. Jerry you are way ahead of me, as usual, what the **** is a flux capacitor? I’ve know Jerry for 35 years and he taught me a lot. I bought this alternator new from Rock Auto after my plane power failed.
 
Suggested Troubleshoot

Fred,
Does your electrical system have an adjustable voltage regulator? I think BillL is on the right track. Did you try turning off either the navcom and/or one of the PFD units to see if the amps recovered?
The flux capacitor is in the same category as a metric screw driver or a bucket of propwash.
Jerry
 
Regulator

My alternator is internally regulated so I can’t adjust it. Rock Auto has brand new alternators at about the same price as the rebuilt ones. I tried the rebuilt ones from NAPA, they lasted about two years. I will try the radio and transponder. I was using flight following and didn’t want to turn those off.
 
Sounds more like a ground/poor termination/weak return path issue (one or all) to me.

Buy me a cup of coffee at Airport Diner some morning and we can have a look :)

B
 
BillL said:
Sure sounds like a bad connection on the field supply wire. The amp demand has to be high enough to make a connection. One might just run a jumper and replace the whole path from power to the alternator to be sure.
Click to expand...

Internally regulated automotive alternator, so it won't have a true field supply wire.

Fred, how many wires do you have going to the little plug?


ND Regulated.jpg
 
Wires

Dr. Horton,
There are two wires going into the alternator, one big one to the post and one small wire that goes into the plug. There is a jumper wire I think for one of the plug wires. It was to hot to pull the plug out and look this morning.

Thanks
 
texdog said:
Wires

Dr. Horton,
There are two wires going into the alternator, one big one to the post and one small wire that goes into the plug. There is a jumper wire I think for one of the plug wires. It was to hot to pull the plug out and look this morning.

Thanks
Click to expand...
 
I have a Subaru with a sense line on the alternator. Need to be carefull when using auto type alternators for our airplane use.
 

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