I have the exact same problem with my Lancair. The amps reading will be steady and then spike negative. The amount will vary. It is caused by electrical noise created by one of my electronic ignitions. I have replaced everything except the ignition system. I have tried relocating the amp probe and even replaced the probe. Turn off that ignition and the problem stops. I have verified that the amps are not changing by using an analog meter. Its just electrical noise. My next try will be to RF choke the leads going to the EIS.
Craig Schulze
Lancair 320
From: Taylor, David [mailto:dtaylor@crescentpark.com]
Sent: Wednesday, October 26, 2011 3:21 AM
To: lml@lancaironline.net
Subject: RE: [LML] Re: Problem with Fluctuating Amperage
Charley, The voltage holds steady. But yes some of the other readings gyrate around slowly and then recover with the amp reading after 30 seconds. I only have one alternator, battery etc – very simple system and plane!
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Charley Brown
Sent: 10-25-11-Tue 21:01
To: lml@lancaironline.net
Subject: [LML] Re: Problem with Fluctuating Amperage
The voltage almost HAS to be fluctuating wildly if the ammeter reading is anywhere near right -- which raises the question, why is it only the fuel readings that are affected? With those amps, the whole system should be flashing on/off... If this is the amperage for the primary alternator... is there a backup alternator involved? Oscillations between primary and backup can be significant if they both regulate to a similar voltage.
Legacy 28V dual alt single batt g900x
On Oct 25, 2011, at 1:01 PM, Dennis Johnson wrote:
What is the voltage reading during this time? Does the Grand Rapids EFIS Sport record data that you can download and study after a flight?
----- Original Message -----
Sent: Tuesday, October 25, 2011 4:50 AM
Subject: [LML] Problem with Fluctuating Amperage
Any ideas about what would cause my amperage to start fluctuating wildly about 5 minutes into a flight?
It starts out fine after takeoff at 15 amps and then goes to -50 amps for 30 seconds, and then gyrates between 5 amps and -50 amps for a minute and then goes back to normal. It repeats this sequence every 5 minutes.
My fuel gages also go down to zero during this episode and then back to normal.
Is my B&C LR3C Linear Regulator going bad?
(I'm getting these readings from my Grand Rapids EIS engine monitor. It's hooked up to a Grand Rapids EFIS Sport.)
Thanks for the help!
David T.
Legacy RG