Alternator Upgrade

[d0tnet]

Few quick questions re: alternator upgrade on a M20J -

 

1.  Any advice on higher performing aftermarket/OEM replacement of the stock 60A alternator on my J model?

 

2.  Should there be a cooling duct run to the alternator?  It appears there is a location for a duct to be mounted on the one being removed (obviously wasn't being utilized)

 

3.  Has anyone added a spacer between the alternator and the baffle?  Seems to be rubbing heavily to the point of requiring some baffle patching.

 

4.  Is it typical of an older alternator to emit large amounts of dust/oil from the brushes?

 

5.  Should all the wiring be proactively replaced? 

 

Thanks in advance.

 

[Guest]

Few quick questions re: alternator upgrade on a M20J -

 

1.  Any advice on higher performing aftermarket/OEM replacement of the stock 60A alternator on my J model?

 

2.  Should there be a cooling duct run to the alternator?  It appears there is a location for a duct to be mounted on the one being removed (obviously wasn't being utilized)

 

3.  Has anyone added a spacer between the alternator and the baffle?  Seems to be rubbing heavily to the point of requiring some baffle patching.

 

4.  Is it typical of an older alternator to emit large amounts of dust/oil from the brushes?

 

5.  Should all the wiring be proactively replaced? 

 

Thanks in advance.

Plane Power makes a very good alternator, maybe less maintainable in the field. As originally installed there is no cooling duct or fan on a J model installation. If the front baffle sealing tapes are in good condition and the sealing material is around the alternator cooling airflow is from the front, through the alternator and out the back. Sealing material around the alternator should protect the alternator and metal baffle from wearing on each other. Normally there is little brush dust emitted from the alternator, they are very easy to remove, inspect and replace. Most common failure is the field power wire or the field ground wire, usually broken from lack of proper securing and resultant vibration.

Clarence

[d0tnet]

Plane Power makes a very good alternator, maybe less maintainable in the field. As originally installed there is no cooling duct or fan on a J model installation. If the front baffle sealing tapes are in good condition and the sealing material is around the alternator cooling airflow is from the front, through the alternator and out the back. Sealing material around the alternator should protect the alternator and metal baffle from wearing on each other. Normally there is little brush dust emitted from the alternator, they are very easy to remove, inspect and replace. Most common failure is the field power wire or the field ground wire, usually broken from lack of proper securing and resultant vibration.

Clarence

Thanks for the info!

Shortly after posting the thread I came across similar recommendations for the Plane Power Alternator. So, I will have one here tomorrow.

After the current alternator failed testing at the local auto shop, looks like the culprit was identified.

[d0tnet]

Another couple of question I just thought of - what is best way to test voltage regulator? Would a bad alternator potentially damage the voltage regulator? What is the typical lifespan of a voltage reg ?

[carusoam]

Search for the name Zeftronics on this site...

Much of what you may find may be oriented around older planes with generators.

The voltage controllers usually last several decades, even the old mechanical ones...

There are some complex ones that control the output of dual alternators for one engine...

Best regards,

-a-

[d0tnet]

Thanks for the info.  I am going to hold off on the voltage regulator for now, from what I gathered they have a long life-span.  Will address that if it becomes an issue.

 

Got the Plane Power unit installed only to realize the belt will not fit.  The Prestolite unit that is being replaced is PN ALY8420R.  Is this normal? 

 

Planning to put on two belts since the prop will have to come off but would like to identify root cause of the difference.

[carusoam]

It's been years since anyone used a second alternator belt that was mounted as a spare...

Belts had changed materials or construction back in the 80s or so. The chance of failure of a properly mounted one is very small.

You might search to see if anyone has recently...

A rubbing belt is a hint of something not being right. Belt, pulleys, or mounting properly?

Best regards,

-a-

[joepilot]

Tagging onto this thread...

94 201J. Have a Kelly Aerospace 70A ALT, 24V system, which I think needs replacing. (Only 425hr since OH in '08) On ground, drops off line at 950 rpm with low load. If I turn a bunch of stuff on, it takes 1200 rpm to get it online (ALT light off) and positive charge on ammeter.

At <1200 rpm, I keep turning stuff on & watch JPI voltage drop to 26.6V, then ALT kicks off. Have to increase >1200 rpm to get it back and get JPI volts to 28+V.

Was inflight the other day, ALT dropped off line. Followed checklist, no avail. Reset Master switch & got back on line.

Shot, right??

Part 2: Is quality back under control at Plane Power to replace??

THANKS!!

-Joe

[Guest]

It's not uncommon for Prestolite alternator output to drop off at lower RPM. Consider having the brushes checked and replaced if required and the slip rings cleaned. All this can be done with the cowl off and the alternator still in place.

Clarence