Then it hit me - The alternator is using an OV protected 5Amp circuit from

the same board… and the lights really seem to sort of flicker (have tried

about 10 different useless solutions for that one).

 

Anyway, the excitation current for the alternator must be right at about 5

amps.  Turns out the micro relay has been tripping, then resetting itself

2-3 times /sec. Turning the alternator on and off with it.  The poor voltage

regulator must have been working overtime as my buss voltage read a steady

14.2V.  The fluctuations were too fast to register on the voltmeter.  The

voltage must have been going from battery voltage up to about 16+ volts to

maintain the average of 14V read by the meter.  As you can guess,

electronics don’t like that kind of thing – but most things worked

surprisingly well.

 

I bypassed the stupid circuit board and connected the alternator field

directly to the alt output.  Wow what a difference.  The EC2 and fuel pumps

were probably the most affected.  All of a sudden I can get idle out of the

ultra rich and put the mixture right.  Idle is MUCH better.  I even had to

reset the idle stop so I could idle lower.  Down to 1000 RPM or less now and

it sounds great.  Oh, the lights stopped flickering and the radios sound

better too.  Go figure.

 

Dave Leonard

 

Dave;

 

That’s interesting.  Makes me wonder whether I should put a scope on voltage and see if it is smooth. 

 

The downside of connecting the field to the output, as I’m sure you know, is that you now have the risk of a runaway voltage condition if the VR fails.  I guess the odds are low, but the costs could be high. Avionics?

 

I assume that you have a breaker (or fuse) in the alt field circuit.  You can put a “crowbar” circuit between the field lead and ground that will trip the breaker in an over-voltage condition.  I got one from Aeroelectric.

 

Al