Alternator Help

[Dayton Murdock]

Hi All
I have a Niagara 40 amp alternator. After starting my engine I turn on the alternator. Lately I have to increase the RPM?s to get the alternator to react in a positive way. After run-up all seems to fine. What?s going on with the alternator? Do I need to clean something?.

[Lycosaurus]

My guess is that the belt is slipping when cold. Once the friction has warmed it up, it is probably adhering better to the pulleys.

It may be something else as well, however I would start with checking the belt tension / wear.

[brianwallis]

Hello Dayton, I'm saving my pennies for one of your throttle quadrants... anyhow... grab the alternator belt and twist it. Not in the direction of rotation but perpendicular to the direction of rotation. Try and get those belt teeth around. The belt should only turn 1/4 of a full turn. Any more than that and you are too loose. Also try and turn the alt pully without the prop moving. If it slips.. that's a giveaway.
Best
Brian Wallis
(standard legal disclamers apply) (ignition off etc...)

[Lycosaurus]

See post #4 for using the torque method of adjust alternator belt tension:

http://www.vansairforce.com/communit...tension+torque

[Dayton Murdock]

Hi All

I adjusted the tension on my alt. belt with the torque medthod as described by Lycosaurus. No Change. Is there a replacement for the Niagara 40 amp alternator?

[Gary Bricker]

Plane Power alt. is a great choice. Good people to work with.

[N941WR]

Originally Posted by Dayton Murdock

Hi All

I adjusted the tension on my alt. belt with the torque medthod as described by Lycosaurus. No Change. Is there a replacement for the Niagara 40 amp alternator?

Dayton,

Why not have your alternator rebuilt locally? That's what we have done with no issues in 200+ hours. (A friend was having trouble with his and I gave him mine to try and he burned it up and had it rebuilt long before my first flight.)

[frankh]

On my old Zodiac I had a 55amp Nippon Denso unit and would do exactly the same thing..In fact pretty much everybodys alternator of this flavour would the same thing.

I.e you have to increase engine RPM before the alternator "woke up"..Once it did it behaved normally back down to idle.

I doubt it has anything to do with belt slippage...Maybe the brushes and communtator (take the back off the alt) could do with a gentle clean.

Other than that, if it doesn't get any worse I would..

1) Ignore it
2) Buy a Plane Power alt kit and have doen with the issue.

Frank

[Dayton Murdock]

Hi All
On Wednesday over the desolation wilderness at 10500' the alternator started to fluctuate again. so undaunted I activated the autopilot (Scotty) and fiddle with the wires under the volt meter. Thinking the meter could be the root of my problems I did a ground check with a fluke meter yesterday. The results were.

Fluke meter 14.43v
Volt meter 14.5v
With everything on in the airplane, engine at idle 700 rpm
Fluke meter 14.45v
Volt meter 14.5v

Alt switch off
Fluke meter 12.33v
Volt meter 12.5v ish

I think I will stay away from the desolation wilderness it causes my RV4 to E-System to fluctuate

[Dayton Murdock]

Hi All
I took my friend Bill Reppucci advice and cleaned the inside of my alternator with contact cleaner. The brush area was contaminated with carbon dust the commutator required polishing. I have operated the alternator over a full spectrum of service conditions without a fluctuation in the output voltage. I think that the root cause the voltage fluctuation has been corrected. I would like to thank all who responded to my post.