New stator melted in 20 miles

J

JimNH

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Jan 4, 2014
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My old stator had one bad leg and although still charging enough I replaced it with a new another 47244 14.5 amp 3 phase. Used the same power box and Sparks rotor. I had .006 minimum clearance. I didn't think to rotate the engine and recheck but I don't think that was the problem. I was impressed the Spark Brite showed correct voltage (green) at idle and would keep it that way even with the halogen headlight on. I started dreaming of a heated vest in the fall.

20 miles into a ride it failed and I headed home. Nothing external noted so I pulled the primary and the stator was cooked. No obvious interference except melted stuff transferred to the rotor. I'm replacing both stator and rotor with new Lucas and am wondering if there's a better regulator to use.

Thoughts?

Thanks
 
Most likely: Rotor and Stator rubbing together - .008" is the minimum and must be checked with the rotor turned to many locations
Less Likely: Regulator or wiring shorted causing the stator to overheat.
Unlikely: Lots of LEDs and too powerful a stator. I only use 10 amp 2-wire or 10.5 amp 3-wire stators as they provide plenty of power for a standard Commando. The 14.5 amp and 16 amp stators should not be used IMHO. Each incandescent bulb you replace with an LED means more power to dissipate in the charging system. With all incandescent bulbs and thngs like heated vests/gloves you might want the higher amp stators.
 
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I actually just checked the note I was writing on the lift and I was wrong, . 008 was the min but, that was in a fixed location. A better forensic examination after scraping off the transfer revealed what may have been a contact area, I don’t know but it’s as good an explanation as any.

No LEDs, all incandescent. I want the extra capacity for extending the season. I tend to be cold anyway so some heat will be welcome.

I’ll be sure to rotate and check multiple locations on the replacement.

Better regulator? It seems silly to be running at max and dumping the rest as heat. Is there a switching regulator available?
 
JimNH said:
Better regulator? It seems silly to be running at max and dumping the rest as heat. Is there a switching regulator available?
Click to expand...

Good question.

However, it does sound like your issue was contact, so no rectifier would have prevented your issue.

It is however ‘a topic’ and one that has differences of opinion (as do most worthy topics). I personally subscribe to the theories put forward by Grant Tiller and fitted a Shindegen SH775 to my Commando, although things like the Tri Spark Mofset also seem very good and are cheaper, smaller and easier to source.

Some reading material here:

granttiller.com

Grant Tiller | Your Bike’s Charging System – Regulator/Rectifiers

*** UPDATED JAN 2021 *** Updated to include views and opinions on the newly launched Tri-Spark MOSFET reg/rec. Table of Contents This article is broken down into sections - you can skip to them by clicking below: Preface Goal More Power Back Then MK3 Commando Triumph T140E Lucas Powerbase...
granttiller.com granttiller.com
 
JimNH said:
Better regulator? It seems silly to be running at max and dumping the rest as heat.
Click to expand...
Silly it’s not and there isn’t much heat involved, unless you have a connection gone high resistance.

Millions of Hondas with shunt regulation don’t burn their alternators.
 
Triton Thrasher said:
Silly it’s not and there isn’t much heat involved, unless you have a connection gone high resistance.

Millions of Hondas with shunt regulation don’t burn their alternators.
Click to expand...
Fast Eddie said:
Good question.

However, it does sound like your issue was contact, so no rectifier would have prevented your issue.

It is however ‘a topic’ and one that has differences of opinion (as do most worthy topics). I personally subscribe to the theories put forward by Grant Tiller and fitted a Shindegen SH775 to my Commando, although things like the Tri Spark Mofset also seem very good and are cheaper, smaller and easier to source.

Some reading material here:

granttiller.com

Grant Tiller | Your Bike’s Charging System – Regulator/Rectifiers

*** UPDATED JAN 2021 *** Updated to include views and opinions on the newly launched Tri-Spark MOSFET reg/rec. Table of Contents This article is broken down into sections - you can skip to them by clicking below: Preface Goal More Power Back Then MK3 Commando Triumph T140E Lucas Powerbase...
granttiller.com granttiller.com
Click to expand...
Thanks for the link! It explains the removed stator which had obviously overheated and definitely not from contact. Being from the '60s hot rod generation where "a little is good, more is better, and too much is just enough" I gravitated to the 14.5 amp stator. The article explains how the stator overheats due to the windings being shorted by the regulator I have fitted. It's over 100 watts and no one holding a 100 watt light bulb would conclude that it's not hot.
I'm now looking to source an SH775 and pigtail, not a knockoff.
 
Triton Thrasher said:
The alternator does not produce its full power (watts) output when it’s shunted.
Click to expand...
Judging from the appearance of the removed stator which was cracked and scorched on the perimeter it was putting out plenty of current back into the AC shorted windings by the Power Box. Since it's a permanent magnet alternator there's no way to shut the field off so it either has to go somewhere or the the output has to be opened.
I'm installing an SH847 series regulator that does just that. It should be a permanent fix and supply me with the extra power I'll want in autumn.
The whole thing got me to look at the systems on the Falcon 7X I fly. The three engines have permanent magnet alternators to backup the FADEC engine controls and two more to backup the Fly By Wire flight control computers. They regulate by opening the output at 28.5 VDC with a more sophisticated system for sure but they don't simply shunt it.
 
Current going through the shunted stator windings doesn’t generate much power because the voltage across the stator is low, because the resistance of the stator coils is low.

By all means fit a Shindengen, but you’re as well knowing what’s going on.
 
Myself if I was fitting a new stator , I would consider having the rotor turned down.008-.010. I also think your changing to a Shindengen regulator is a good option. I have gone through this problem more than once making sure I had the minimum.008 clearance on various positions and still had them melt.You will get many opinions on this and this is just mine. I also run a heated vest in the winter with no issues.
Mike
 
Triton Thrasher said:
I’ve read the stuff in the past and I remember not being convinced by some of it.

An argument that the shunt regulation on millions of bikes doesn’t work is not something I take seriously.
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Who is arguing that shunt regulators don't work? The point is that I've probably upset the balance of power in installing a bigger stator than is needed. It will be needed with heated clothing. If you read the whole article it comes to that conclusion reinforced by my observation that the perimeter of my last 14.5 amp stator is obviously overheated.
Without modifying the system - installing a high capacity stator, it would probably work fine. The original MKIII charging system, however, is really not adequate for running with a halogen headlight and keeping the battery up to snuff. I had an early Boyer ignition system that Dyno Dave discovered would fire randomly on low voltage resulting in failed and even a locked sprag which left me stranded. 3 phase alternator, Dyno Dave starter, and Pazon ignition and it became a reliable E-start bike.
 
concours said:
Yeah, I watched a friend open the primary to reveal a burned up Sparx stator.

Like naming a boat company: "Sinker"😜
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I think i know that guy....speaking of turning down a rotor, anyone here done it personally? Just wondering how they cut.
 
MikeG said:
I think i know that guy....speaking of turning down a rotor, anyone here done it personally? Just wondering how they cut.
Click to expand...
Lots of people turn them down. I'm sure there are lots of opinions on what cutters to use. Personally, I would not use a high-speed steel cutter as it could affect the magnetism. Ceramic or carbide inserts should be fine.
 
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