Preventative replacement of alternator?
 

I found a new aftermarket alternator (for $80) that i was thinking of preventative replacing on my e70 N52 X5 with 211k miles


Or just getting it to have as a spare in case mine ever fails


Mine seems to still chug along well but is this something that fails out of the blue?

I don't think so, I plan to at 200k, but I'm going to use a Bosch remanufactured or a BMW one. Rather do it once and using one of those will increase that odd.

They will always wear out the slip rings and brushes.

Having a spare is not a bad idea.


–awr–

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Who makes that $80 aftermarket alternator?

I wouldn't ever buy Bosch again. I did that on my E53 and it lasted around 17k miles before it failed.


I was actually just thinking of this for my E70 though. I'm big on preventative maintenance and I think mine is original at around 146k miles. What would you guys go with if you were going to replace it? I am actually going to do belts soon so I could do this at the same time.

The Bosch rebuilt should be good but the new Bosch that I once ordered was chinesium. That market changes pretty fast and it's hard to keep up with what is good any more!

I put a Bosch rebuilt alternator in when I did the motor swap a few years and around 20k ago. So far so good.

I have the original alternator that came out of the x5 during the swap and there is a shop in town that claims to be able to rebuild the Bosh water cooled units. BMW states otherwise. Obviously they can be rebuilt, so is this just BMW steering business to a Bosch company?

I’ve decided to swap my original 4.4 over to the air cooled alternator as part of the rebuild, but maybe I’ll have it rebuilt as a spare.

I have a lot of spares this and that. Some oem or aftermarket.
Its a great feeling to need a part especially on a Saturday and to know you have that needed part on the shelf at home. Less stresses if you ask me! No waiting for even express delivery.

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I had a refrub bosch fail on the 2nd or 3rd drive. I traded it in for a new valeo at O'Reilly auto. Came with lifetime warranty. There are O'Reilly throughout the country and alternator is a mission critical part.

I've rebuilt the valeo at about 140.000 mi. and it lasted 40-50,000. I didn't autopsy to determine the fault but it likely was other than the brushes and rings which is what i replaced.

The Valeo repair kit was only $20 at the time i would prob be comfortable with swapping in this $80 model and rebuild the current one for $30 say and have that as a spare.

It's not difficult to rebuild the VR and replace the slip rings.

The second time i rebuild one i just replaced the brushes and flipped the polarity of the slip rings since 80% of the wear was on one ring. Rather than replaced the rings i just set it to wear down the other ring basically resetting the wear clock 100,000 miles with $12 of brushes and an hour of time.

I have a thread on xo showing how to do the polarity swap. IIRC, i cut the conduction bars and soldered wires criss/cross to swap the polarity.


–awr–

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Mine was a Bosch rebuilt unit that failed prematurely, not a new one. Bosch "rebuilt" units are done by some chinese third party under license. The second time I replace it, it was easy to spend a few extra bucks for a Valeo.

Yep, the way things change these days with companies it's a crap shoot! ;)
When I bought a Bosch rebuilt it was more expensive than the new Bosch but turned out to be good.

It's a dice throw. That said alternator swap on m54 is about 3/10 difficulty sou recommend getting whichever didn't raise your Spidey sense but get it from a big national brand with stores within a bike ride distance and a lifetime warranty.


–awr–

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I just checked and Valeo is the original manufacturer for the 220-amp alternator on my 35d (according to RealOEM).


Part number 12317603775 is the voltage regulator and is only about $60 for a Valeo version. Andrew, do you know if I need any special tools to remove the voltage regulator? The last time I did this was on a Toyota about 15 years ago and it was just attached to the end of the alternator. But FCP has a bunch of "decoupler" tools in their section for the alternator. Just want to check before I take the car apart.


Edit: Nevermind, it appears you can access it on the back of the alternator if you take it off.

I have a write up on xoutpost that shows how I actually refurbished mine and I’m pretty sure it shows the process of removing and reinstalling.

it was quite a while ago. I can’t remember if soldering was involved. I of course, did Saturn because I switched the polarity of the field winding.


–awr–

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My 190k alternator died yesterday afternoon. Got a cheap Duralast in there to get me on the road but I'm rebuilding my original alternator and replacing the overrun pulley along with all of the other front accessory drive components including a Fluidampr unit.

Share the steps when you do it. I'm very much behind repair. I rebuilt both mine and wife's e53 alternator


–awr–

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The Valeo regulator is very easy to replace, no soldering required. However, finding the 230 Amp one proved impossible (or not economically feasible) when I was looking for one. When I was replacing the engine decided to take out the one in my alternator (@ 169K miles) and found out that the brushes were almost completely disappeared. There were some grooves in the slip rings also. I didn't realized it at the time that I had a 230 AMP regulator and purchased a 180 one just to be greeted with the "incorrect alternator" (or something like that) error message. Digging around I only found that Autozone had a 220 Amps CarQuest with lifetime warranty so I figured out that if it dies there are plenty of their store around. So far, so good no issues with it but only time will tell. At least in the N63 is right on top of everything (takes more time to remove the fan and serpentine belt than the alternator itself!)

Valeo 220A and the same part number for my 2011 35d.

The decoupler is a overrunning or clutched pulley that diesels should have on their alternators. INA, BMWDieselParts, and Litens all make the correct pulley. I plan to use a Litens when I rebuild mine. These type of pulleys require a tool, not exactly a tool, but a technique to remove the pulley. Basically a socket with wrench flats and a hole to pass the Torx bit through.

Preventative replacement of alternator?
 

You should notice that the slip rings wear almost exclusively on one polarity. When i change the VR but not the slip rings i will change the polarity of the slip rings. Much easier than changing the slip rings.

https://xoutpost.com/bmw-sav-forums/...eo-alternaror-

My second valeo refurbish. I swapped the brushes and slip ring polarity.

I came up with an easier method to swap the polarity by cutting the conductive bars going to the brushes and soldering jumpers.

I think that method may apply to Bosch VR though i will see if i can find a photo

https://uploads.tapatalk-cdn.com/202...6e327cbb92.jpg


https://uploads.tapatalk-cdn.com/202...7e8c9427df.jpg

A couple photos to show how uneven the wear is on the slip rings.

If the VR simply swapped polarity every restart the alternator would last maybe 50% longer. (would make both the slip rings and the brushes wear evenly)

This still slightly puzzles me how the wear is so different depending on the polarity of exitation on those gliding surfaces. The same current flows thru both of them anyways.

Ones side sends electrons one side receives.

With arc lamps the anode is about 12x as massive to deal with the pounding.

https://uploads.tapatalk-cdn.com/202...de2d18c7cd.jpg

I suspect a similar situation is going on. (I love how the ± are cut into the contacts)

Anyhow it's definitely a fact of life/physics and the field winding doesn't give a crap which way the current flows. It'll make N-S instead of S-N at the field winding but when it's spinning it doesn't matter at all.


–awr–

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Doesn't it cause phase shift and lag on the alternator or is the optimal phase shift so close to 180 degrees that the change is negligible?

The windings generate A/C which gets converted to DC with the diodes so phase is meaningless.
Electrons flow from negative to positive and take material with them as they leave which is how cathodic protection (pipe lines, boat motors) works ;)

I was talking about the excitation side of things but was too much thinking it as a motor. On exciter side it doesn't matter which of the poles are north and south. This slip ring wearing is just a simple matter of DC arcing.

Alternator has no idea. The phase of the 3 AC phases is shifted but the start point is completly arbitrary and as 80s mentioned the ≈ 400hz three phase AC is rectified to DC.

I wondered for decades how on earth does the car regulate the output and can usually maintain 13.8 ± 0.2v regardless of the RPM or load.

It's actually so simple: there's a direct feedback loop that increases the field winding current if voltage is less than the set/design voltage.

Higher field current, stronger magnetic field, higher 3-phase AC voltage that's rectified.

It's fully automatic and virtually instantaneous.


–awr–

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Clearly, there is a difference in ring wear on this alternator. I don't think it's due to polarity, though. As mentioned, the current flow through each is the same. There is some excitation differences and it is true that slip rings will wear differently, but on a small generator like this, we're talking microns over the 5000 hours of operation an alternator might see. On much larger (multi-KW) generators, slip ring wear is indeed monitored and accounted for. Polarities are switched on a schedule, but the currents are much higher, they're in constant operation and service lives are measured in decades. More than likely, it's that the alternator works in the worst environment imaginable for a brushed machine. It's hot, oily, and dirty all of which will increase brush and slip ring wear on a much more meaningful and noticeable scale.

Preventative replacement of alternator?
 

There's literally only one difference between the two slip rings (polarity), and if big generators switch polarities, there's the answer. As crazy as it seems, it has to be the why.

It’s a bit crazy that 6000 hours will do it in. I've collected dozens of end-of-life arc lamps, and the anode made of over half a pound of tungsten is beat to hell, and there's never wear on the cathode.

If you compare the flux density of the current through the brushes, I suspect that will play into the equation heavily.

I don't know what the current through the field coils is typically, but when the engine is cold and running at idle, I'm sure there's a healthy chunk of the 1.5 to 2.5 kw output going back into the armature, and those brushes have maybe 1/10th square inch contact patch.

https://uploads.tapatalk-cdn.com/202...caa4931fd3.jpg


–awr–

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https://uploads.tapatalk-cdn.com/202...875f50ef16.jpg

The abridged version of my brush polarity swap.

I measured the difference in the wear and it is about 4x the rate of wear on the one that takes the abuse.

I'm telling you it's not. I've seen it many times in much, much, much larger generators. Increased brush wear or slip ring grooving in between monthly or biannual maintenance periods always attributed to a change in operating conditions or contamination. Flexibrasing or a quick stoning would bring it back where we'd want it and we'd replace the brushes. On DC generators it was more apparent but commutator action is MUCH more aggressive and much more affected by high temperature and contamination. The polarity swap was done on every 36.months on the multi-gigawatt AC generator and 72 months on a moderately sized few hundred-KW AC generator. The larger generator is expected to be in service for 40 years, the smaller one runs continuously and is generally overhauled every eight or nine years. Again, even on these larger generators with much larger current, we'd expect millimeters over their service lives. An alternator's life is too short, and it's just too small for this action to noticeably affect ring wear. Operating conditions have much more of an affect. There's nothing wrong with swapping the polarities, though.

I'm agreeing it's the operating conditions. But it's causing an exponential increase in the only candidate for one side wearing faster than the other.

Next time i have an alternator apart i will confirm which polarity gets the abuse. It's always one side and every alternator it's the same story.


–awr–

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Very little current is needed, a few milliamps in the case of water heaters and underground gas tanks, larger distances of pipeline gets into amps and the current needs to be impressed, alternator field is a few amps so for sure a factor.
I was told in the old days they used to bury an old car beside the pipeline, connect it and impress a bit of current to make sure it was the car giving off the electrons and being sacrificed and the pipe taking them in. ;)

In the big generators there is so much else going on that the transfer is probably not noticed as much.

The Litens website doesn't show any parts for our cars.


What do you need to install this one? https://www.bmwdieselparts.com/produ...51026059657384

Litens and INA do not show parts for the E70 X5 in their catalogs. You will find the INA OAP listed on retailers' websites, however. Litens pulley is an OAD and works sightly differently than the INA and BMW Diesel Parts OAP. I'm going to install a Fluidampr so I actually am going with the OAP now. INA is an OEM to BMW for belt drive components. BMW Diesel Parts seems decent, but I've never perosnally dealt with them. FCP Euro sells the OEM INA p/n EA0183 and Cascade German Parts has what might be the OE M57 BMW p/n 12 31 7 560 483. You need to be sure that the required spacer is included or ensure you buy one and install it. Old pulley should come off (I'm not sure all or any X5s got the OAP hence tge lack of catalog cross reference) and you might need an OAP install tool to torque the new one on. The new OAP should have a cover/protector included also.

Finally rebuilt my alternator and installing it soon. I dressed the slip rings for the new brushes, replaced the rectifier, and bearings, sand blasted the frame and cleaned everything well and installed a new OAP.. Looks about 95% of new. Very, very happy.

Feels good! I didn't bother cleaning before i took it for testing and the guys at the auto shop were very surprised that it tested perfect


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