tolsen

Alternator no longer charging

18 posts in this topic

Problem started yesterday. Wife reported a strange light had appeared in the instrumentation panel which I concluded was the battery charge light. 

Alternator is as old as the car a 2002 Smart Cabrio Cdi now having clocked 249,000 km. 

I suspect worn out carbon brushes and willl soon find out but unlikely before the coming weekend when I intend to lower rear subframe to remove alternator. Will of course carry out certain diagnostics checks first. 

 

 

 

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4 hours ago, LooseLugNuts said:

quarter million km on one alternator is pretty good 

Impressive in my humble opinion given its position fully exposed to the elements. 

 

I hope I can get away with a rebuild provided the housing parts have not disintegrated. 

Regulator is £28, slip ring £6 and bearings about £4. 

 

Many years ago possibly around 2005, this alternator seized up whilst at dealer for clutch trouble repairs. I then opened out alternator, increased internal air gap by machining and varnished its windings and housing. Can now only pray the alternator is still in good enough condition to allow reconditioning. 

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Posted (edited) · Report post

75,000 km on my 2005 smart.

 

After unseizing my alternator, a few weeks later I also experienced the no charge indicator light on my dash.

 

I'm not a happy camper and am curious what type of fault (from corrosion?) occurred a few weeks after the alternator was unseized.

Edited by smartdriver

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Could just be a voltage regulator failure.

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I guess worn out carbon brushes and or slip ring. Surprised this alternator lasted so long. Most would have given up the ghost years before mine at only a fraction of the 249,000 km my Smart has done. 

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What exactly did you do to your altenator to allow more clearances to help stop the siezing problems...etc....thanks. any pics..?

 

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I simply turned down its rotor on a lathe. 

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Of course lost a few amps doing that but never did it seize up ever again. 

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Any negative issues with lower amps?

How much did you remove?

 

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I have now partly opened out alternator and pretty sure I have identified the fault:

 

212-EEE38-4815-4-F3-A-A09-E-F68744-DA96-

 

Fault appears to be bad contact on crimp connections to diodes.  Intend to clean these applying both good elbow grease and hydrochloric acid and then solder them all.  Will be a rather cheap repair if it works.

 

Carbon brushes and collector rings are fine.  Plenty of life left. No more than 0.3 mm wear on collector rings.

 

B100334-C-8-E17-4-BB3-B753-3619-D5675-BC

 

17594599-2-FB8-4195-8662-431289-B99-DAC.

 

Bad contact on crimp connections explains why this alternator charged for a very short time about a couple of minutes after engine start and why it would later charge for another few minutes whilst driving then conk out.

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On 05/12/2018 at 9:48 PM, Willys said:

Any negative issues with lower amps?

How much did you remove?

 

No negative issues as alternator has worked fine for nearly 12 years after skimming its rotor.  I did not remobe much perhaps no more than 0.25 mm on the radius.

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The bad crimps are the two at bottom of photo. You can clearly see bright copper indicating these have gone hot. Will of course clean and solder all including the stator winding solder points. 

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Bearings are still fine with no rumble so I have decided not to renew at this time. Opened bearings out in 2006 or 2007 when alternator was hard seized up and cleaned and regressed bearings. 

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I cleaned and soldered all diodes but regrettably alternator is still not charging except briefly shortly after engine start at end of glow plug post start glow period. 

 

These alternators have digital field hence bench testing requirers special and costly equipment. 

 

Have ordered a new regulator and a second hand 2012 alternator off a 451 Cdi with less than 2000 claimed miles on it. 

 

30B240EE-E687-4C40-B9B4-BBCE527EB16B.jpeg

Note special free wheeling pulley on this 451 alternator. 

 

2D8F6885-6F2A-46FF-AC99-62F93C32B29F.jpeg

 

451 regulator is unlikely to work in my 450. Not sure if I will dare try it without first fitting right type regulator for my model. 

 

Both regulator and alternator may be delayed due to Christmas parcel rush. 

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Very nice, the altenator that is....far cleaner than either of mine...lol.  OK, is the new version bigger, pushing more amps? Is it better designed as in no more siezing issues?  OR is it just something to try?

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90A whilst ours are rated at 85A. Looks identical apart from part numbers. Also the socket although looks identical is slightly different hence impossible to connect to a 450 plug. Must therefore replace its regulator. Alternator arrived today and looks better than in the two photos.  

 

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Have concluded existing alternator is not getting power to excite the field. On mine field excite power comes from rear fuse and relay box which 450 models with SAM fuse box do not have. Found an electrical diagram in WIS (Mercedes work shop system) for rear box but wiring does not seem to match what mine has. 

DF appears only to be a signal advising glow plug controller what charge rate is.  This means I can easily bench test my existing alternator. All I need do is run 12 volt to it in series with a 30 Ohm minium 1/3 Watt resistor.  

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