Alternator alternatives

[NotarPilot]

Looks like I'm due for a new alternator soon.  I currently have the Prestolite ALY-8420.  When I checked with Spruce they don't have one but they have the ALY-8520.  Is that compatible?  I understand Kelly Aerospace bought Prestolite but from reading some of the comments on here it seems people prefer the Plane Power (?) alternator.  

 

Any comments or suggestions?  Is the ALY-8520 an alternator that will fit in place of the 8420?  

 

Discuss.

[KSMooniac]

I have an ALY-8520R for sale (http://mooneyspace.com/topic/8538-12v60a-alternator-for-lycoming/) that came off my 14V salvage J, and it was a recent installation as far as I can tell so I suspect the 8520 supercedes the 8420 but I'm too lazy to search for confirmation.      Kelly had the Prestolite line, and Hartzell Engine Technologies bought Kelly, so HET is the vendor now.

 

I installed a Plane Power alternator on my flying J a couple of years ago and like it so far.  

[N201MKTurbo]

Why don't you just get it overhauled? it is about 1/3 the price and the overhaulers will make it like brand new.

[NotarPilot]

I didn't think about that but that sounds like something to look into. Thanks.

[bnicolette]

I upgraded to a Plane Power alternator.  I also took my Kelly alternator to a local generator/alternator repair shop and had it repaired.  It cost me $30 and then I sold it on ebay.  It got snagged right up by the homebuilder crowd.

 

Food for thought.

[OR75]

i still have a prestolite/kelly and it has worked flawlessly. ( it still supplies voltage and amps even though apparently it being a low grade).

question: what makes you think you may need a new alternator ? alternator usually work or don't - meaning either supplying the right volts and amps or 0.

[N201MKTurbo]

One of the common failures is one of the six diodes will fail, usually because of a fracture in a solder joint, this causes one of the three phases to fail reducing the output by a third. If you loose two phases the alternator will still work, but at a very low capacity.

You can also get an open in the stator windings causing the loss of one of the three phases.

So, alternators don't either work or not work.

When you loose a phase you will hear an increase in alternator noise in your audio system, a whine that varies with engine speed and gets louder if you increase the load by doing something like turning on the landing light.

[OR75]

Well , if the capacity is very low, it is not working . The battery won't last long

[N201MKTurbo]

Well, that depends....

If you don't fly long enough to charge the battery, it will get discharged and won't start the plane. If you leave it discharged long enough it will get sulphated and it will not charge. Even with a severely crippled alternator, if you fly long enough, with a light enough load the battery I'll charge. You can operate with a damaged alternator for a long time.

[NotarPilot]

I have about 1,100 hours on my alternator and my IA says they should be replaced at about 1,000.  He recommends replacing the voltage regulator at the same time.

[N201MKTurbo]

Modern solid state voltage regulators should last forever. I guess vibration could shake the parts apart.

I have never had an alternator fail suddenly, they generally give a lot of warning that they are sick. The only thing that wears out is the brushes and they will last way more then 2000 hours.

I think I have had six alternator failures in the two Mooneys I've owned. None have completely quit during flight. Maybe I'm just lucky.

I have had the field wire break during flight which makes the alternator stop working, but its not the alternator that failed.

If you will sleep better with with a new alternator, then go for it. I'm sure your mechanic will appreciate the extra work.

FWIW if you have an alternator overhauled, make sure they replace the bushings in the mounting tabs. They usually don't replace them and they are always warn out.

[NotarPilot]

Well, it's nothing that needs immediate attention and I don't think my mechanic is trying to make extra work.  There have been several things I thought needed attention in the past that he's looked at and said it could be deferred to a later date.  Such as my brake pads I thought needed changing last week.  He looked them at my annual in Oct and said they should be changed in the next 50 hrs.  Last week he looked at them again and said they're still good and could wait til the next annual.  

 

So that being that, he said the alternator could wait til the next annual provided it doesn't give me any problems.  I guess alternators should be changed or overhauled every 1,000 is what I'm told. Mine has 1,100.  

 

Are you saying I should leave the alternator as is until it starts giving me warning signs that it's sick?

[carqwik]

FWIW, I had an alternator fail in-flight...two minutes after passing through a heavy rain shower and moderate turbulence. (There are two in the Bravo thankfully so it wasn't a big deal.)  Original equipment Lycoming (I think it is a Prestolite IIRC)....was going to get it OH'd but decided to install the PlanePower alternator instead.  Saved 2 lbs up front...and the PlanePower has worked great so far. 

[NotarPilot]

Will that Plane Power fit on a J model? Whats the model number?

[Awful_Charlie]

FWIW, I had an alternator fail in-flight...two minutes after passing through a heavy rain shower and moderate turbulence. (There are two in the Bravo thankfully so it wasn't a big deal.)  Original equipment Lycoming (I think it is a Prestolite IIRC)....was going to get it OH'd but decided to install the PlanePower alternator instead.  Saved 2 lbs up front...and the PlanePower has worked great so far. 

Did you drop to a single alternator as part of that conversion?  I would love to get some weight out of the nose, but http://www.plane-power.com/Fit%20Guide%20Transition.htm suggests that only single alternator installations are eligible

[NotarPilot]

Does anyone have any idea how many hours of labor I should expect for the alternator and voltage regulator to be replaced?  I think I'm going to replace it with the Plane Power.

[1964-M20E]

I put the plane power on my former plane to replace the generator ans could not have been happier.

[Wistarmo]

^{I installed PlanePower and it works great.  Technical support is good as well if you need to talk with them.}

[KSMooniac]

Does anyone have any idea how many hours of labor I should expect for the alternator and voltage regulator to be replaced?  I think I'm going to replace it with the Plane Power.

 

I'm guessing 3 hours or less for a pro... I did mine myself but can't remember how long I spent.  It isn't that difficult, except for the contortionist act under the panel to get to the regulator.

[NotarPilot]

Thanks Scott.  At $95 an hour for my A&P I was curious how much I would need to budget for this.

[OR75]

The alternator is really easy to get to and R&R.  Make sure you get the right tension on the belt - not too loose - not too tight

 

the voltage regulator is a pain in the b... to get to. If it is not, broken , leave it alone

[KSMooniac]

Thanks Scott.  At $95 an hour for my A&P I was curious how much I would need to budget for this.

That's just a bit of an educated guess on my part.  Alternator access isn't bad, but working the cotter keys on the mounting bolts/nuts is a bit of a PITA but not awful compared to other Mooney MX tasks.   

[NotarPilot]

I went with a Plane Power AL12-P70.  I'm going to have it installed next week.  Just to confirm, this is a direct replacement part being that it's a PMA and not an STC and therefore no 337 needed correct?