[Dr. Montano]

Hello all:

My alternator dyed again. Second time.

I’m going to describe the situation hoping it is of interest or of use to others. Also because I have some questions I’m hoping someone here can help me with. Any and all comments are most welcome. Plus writing things up helps to clear things up, so maybe I’ll have answers in mind when I send this.

My motorcycle is an BMW R1200RT 2015. Here are some further details:

Vin checker data - BMW K52 R120 2014 san-marino-blau met./granit-grau met. - - WB10A0308FZ240505:
(Motor / VIN / Serial No.: WB10A0308FZ240505)
VIN: Z240505. Prod. Date: 2014-10-11. Type: R1200RT. Series: K52 (1 Series).
Steering: Left Hand Drive. Engine: A74. Transmission: Manual
Other Equipment: X0143 Bluetooth Interface. X0191 Dynamic ESA. X0193 Keyless Ride. X0202 Daytime Running Lights. X0204 Hill Start Control. X0219 Deluxe Headlight. X0222 Gearshift Assistant Pro. X0224 Driving Modes Pro. X0230 Comfort Package. X0233 Touring Package. X0235 Dynamic Package. X0268 Audiosystem ECE. X0272 Preparation, Navigation Unit. X0350 Exhaust System, Chrome. X0376 BMW US Radio. X0383 Operating. Instructions, Spanish. X0417 Central Locking System. X0518 Seat Heating. X0530 RDC. X0538 Cruise Control. X0603 Alarm System. X0764 Plug-In Socket.

Already once before the stator coils burned. Only 66K KM on the clock. So the motorcycle had to be taken apart completely and the windings were re-done by a real artist in the matter. The mechanic is an artist too, but they took their time. Nobody had ever touched the bike but myself before, to change the oil, filter, brake pad and tire changes. It bothered me that the bike had to be taken apart and I was fearing it would never be back to what it once was. However, they did a great job and the motorcycle worked just great again. Additionally, labour here is not as expensive as in the US.

Here is the description of that first repair in this forum:
R1200 LC 2014+ Charging system diagnosis

That repair lasted only two years and 20K KM though. Definitely it was not the correct repair. I’m hoping to get it right this time, for at least another 100K KM. That is why I’m trying to study this more carefully and hope to have some advice here also.

There is a long thread on this matter in this forum that I consulted then and again yesterday. It has a lot of info on the matter:
ALTERNATOR PROBLEM WET HEAD

It is indicated in this forum that one should start a new thread, rather than piling info on an old thread, so that is what I’m doing. But the aforementioned “Alternator problem wet head” thread is great. For example, RealShelby in post #68 there explains basic electricity concepts such as voltage, current and power very clearly. I had never been able to understand these before. And about everything else about this alternator / regulator-rectifier setup is also discussed.

There is also a great PDF by Nicholas Van den Berg on the UKGSer forum that explains in detail how to diagnose this problem easily: To check the stator you disconnect the three yellow wire connector at the Regulator/Rectifier under the seat and see that there is continuity between all three cables but not with ground.

Last night I checked just that and found continuity from all three yellow stator cables that connect to the regulator-rectifier (R-R) and ground: The stator is dead.

If possible, please correct me where I’m wrong. There are several things that I need to verify, before I can decide how to deal with this repair, again, if possible reducing costs, short and long term, but also to have the repair last:

• I have to start by saying that I would not buy a motorcycle that there was not a Haynes manual for. Also that I have no beef with Chinese or alternate manufacturer parts: My rear brake disk is a cheap Chinese one which cost me 10 times less than the BMW original and is in perfect condition, after about five sets of pads and some 70K KM. That said, evidently there are different qualities, but also unfair prices from some vendors.
• After reading up again, I understand that the stator is called a stator because it is static: It does not move.
• The stator in this motorcycle has 15 poles (bits that protrude and have winding on them).
• The new alternator that supersedes and replaces the one originally installed in this engine and motorcycle (VIN: Z240505. Prod. Date: 2014-10-11. Type: R1200RT. Series: K52 1 Series.) has 21 poles. They are thinner and seem taller, plus there are some bigger holes, all of it to keep it cooler it seems. (That is explained in the long thread linked above.)
• Question No. 1: Reading up on a site about “Essential Magnetics” it would seem that if the “stator” is the part that is static, then the metal cover on this alternator must be the “rotor” which spins and must have magnets or something: ¿Is this correct?
• It seems that if the stator has 15 poles, the cover (rotor) does not necessarily have 15 magnets. There are no clear pictures I can find of the cover, much less with detailed measurements.
• Question No. 2: ¿Can the stator with 21 poles replace the stator with 15 poles inside the original casing (rotor)? It seems not, but if so: Have you actually done it and is it working correctly? (This was a question that I have not found clearly resolved. Lolo28fr in post #146 of the previously referenced thread seems to have tried an RMStator (21 pole) to replace the original (15 pole) and failed.)
• There are a variety of 21 pole stators available that all seem to be very similar. Starting with the Chinese ones on AliExpress at about US$100 with shipping, then the RMStator one at about US$260 plus shipping and the original OEM BMW Alternator which can only be purchased complete with the stator inside (but without the regulator-rectifier) for about US$1,300 plus shipping.
• If the casing is actually different for the 15 pole and the 21 pole stator (which seems likely) then I might be able to find a used alternator of the newer kind at a US breaker and place the stator inside with a new one. (If I were to use the chinese stator and a cheap used casing for the 21 pole stator, that might bring down the cost a lot. Note that labour costs here are not as high as in the US or Europe.)
• Going to all that trouble might not be worth it if the quality of the original alternator is really five times better and would really last a lot longer. In my experience, that is not necessarily the case. So a repair might be good. (Opinions might differ greatly in this.)

It seems this original 15 pole alternator really was a design fault. Such an expensive motorcycle should function well for longer without such complicated repairs, but I also must state the following, for consideration:

• Before the stator first failed on my motorcycle I was spending time doing figures 8 in the parking lot. I was a bit tired of being locked up. Slow driving and a lot of clutch use. It did wonders to my control of the bike.
• After the repair I replaced the standard battery with a lithium Antigravity Re-start battery. This it seems might put additional stress on the alternator and is non standard. (There seems however to be a specific regulator-rectifier now for such batteries at RMStator.)

If you have read all the way down here: Thank you! You are patient. It is much appreciated. Hope is can also be of use.

Any and all comments, whatever they are will be very welcome and appreciated.

 

[beech]

Many time when an alternator fails it is recommended to install a new regulator. The thinking is the regulator may have contributed to the failure. I have not read all the information you have cited yet but will. This is just thinking out of the box. I can't remember if your alternator showed sighs of mechanical issues causing the failure?

 

[Dr. Montano]

I can't remember if your alternator showed sighs of mechanical issues causing the failure?

No mechanical issues. Coils were burnt, but everything else was clean and fine.
I did change the regulator-rectifier for an OEM one not long after the repair of the stator.

 

[The_real_hati]

if the “stator” is the part that is static, then the metal cover on this alternator must be the “rotor” which spins and must have magnets or something: ¿Is this correct?

Not sure what exactly you call "cover" but yes, the stator needs a rotor to be able to generate electricity.

After the repair I replaced the standard battery with a lithium Antigravity Re-start battery. This it seems might put additional stress on the alternator and is non standard.

It should not. Unless its internal battery management board failed and allows way too much current to be absorbed, therefore placing an unacceptably high load on the alternator.

The problem with lithium in general is that it has to be managed very precisely, while lead-acid batteries do not. The bike's battery charging circuit is designed with lead-acid in mind, that by itself is not suitable to charge any lithium battery. Enter BMS, (battery management system) that is designed to look after the fussy lithium cells by limiting current input and output, protects from over and under charge as well as reverse polarity and balances the cells. While it is very rare, they can fail, at which point you could in theory, overload your alternator. The problem is if you develop this situation, likely your lithium battery will go up in flames. In conclusion I doubt the use of your Antigravity battery killed the alternator.

 

[Dr. Montano]

1) Yes, the stator needs a rotor to be able to generate electricity.
2) Enter BMS, (battery management system) that is designed to look after the fussy lithium cells by limiting current input and output.
3) I doubt the use of your Antigravity battery killed the alternator.

Many thanks:
1) Yes, I understand the stator is the part around the stator with its poles. It looks like a cover or encasing to me.
2) It seems the Antigravity Re-Start battery has that BMS inside. That is what is explained. The battery shuts down when it's being drained beyond a limit that makes it possible to start the battery. (Thus the "Re-Start" name.) But it does other stuff too, i.e. BMS.
3) Good to know.

Your help and knowledge much appreciated.

 

[Geekmaster]

One thing you might try as you replace your stator is a different voltage regulator. I posted on the MOA forum about my research in replacing the voltage regulator with a different model that runs the stator cooler. Here's the link so you can read the details:

https://forums.bmwmoa.org/showthread.php?103522-Shindengen-SH847

Also, I understood that the redesigned BMW stator fits in the existing rotor, but not having done it, I cannot be sure. At $1300, it's insanely expensive, but it would be worth it to avoid removing the engine every couple of years.

 

[Dr. Montano]

Thanks Geekmaster:

• Yes, I'm looking into the regulator. Will read the post indicated with care.
• We'll see if someone has a definite answer regarding the new stator (21 pole) in the existing rotor (originally 15 pole stator). In the end yes, the OEM part might be the way to go.

 

[Audi403]

I would not use a cheap chinese alternator. They are not going to be built to the same standard as the BMW product. My education and work experience is in the electrical field. For how much work it is to change, I would not trust any of these cheaply built electrical components.

 

[beech]

I have seen several photos of replacement stators. Not one looks as well made as the oem unit. Here is one from euromotoelectric who I trust as a fair supplier but it too looks a little crude. You would have to do the math on labor rates where you are to insert it vs cost for the OEM unit and its possible benefits.

 

[beech]

Here is one I'd buy in a second:

BMW R 1200 GS ABS LC 2013 - 2016 Alternator Stator | eBay

Find many great new & used options and get the best deals for BMW R 1200 GS ABS LC 2013 - 2016 Alternator Stator at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Dr. Montano]

Since it is not at all clear that I can put a 21 pole stator where the 15 pole stator was, then most of these very valid considerations end up being beside the point. There seems not to be a used alternator / rotor that I can get for less where I could put any of these. So it looks very much like the whole OEM Alternator at the whoping US$1,300 will have to be the one to install.

It seems that the choice of Regulator-Rectifier is still something to continue thinking about. Since I have the indicated Re-Start lithium battery, it looks like the RMStator R-R for lithium batteries would be good. Especially if it helps to keep the stator less stressed or cooler.

Every one of your comments very much appreciated: Thanks.

 

[Scott9999]

I'm not going to dig up the pictures again or part numbers, but BMW replaced the alternator stator on the 2014 (and maybe 2015) models with an upgraded part. The pictures of the original look like they were wound by a grade school kid. The new part looks far more robust, and looks like it was printed on a 3D printer, i.e. much tighter, uniform windings. If you haven't looked into that difference, do some thread searched here and on bmwrt.com, and the issue should pop up. If you're rewinding the older OEM one, dump it and buy the newer parts.

(I'm being a bit vague here about alternator, stator, rotor, etc., because I'm being lazy and not fully refreshing my memory on the technology, and ... well, I'm older and I forget the detailed stuff easily. 🙄)

 

[The_real_hati]

There is an other solution here, albeit would take more time. You can always get the second original stator rewound if you can find a decent winding shop. They can easily measure the wire size, count the thread on each of the poles and wind connect the three sets of poles together.

The likely reason for the failure is the quality of workmanship combined with possible poor lacquer cover and quality of the wires. A new rectifier would also be a must. I deal with electric motors on a daily basis, generators/alternators are essentially electric motors used "backwards" and the quality of windings is critical in every case.

What I would do in this instance, assuming @Dr. Montano is capable of this is to dismantle the bike, take the burnt up stator to the winding business that has the highest recommendation in the area, then get one of the "serial" rectifiers to attempt to introduce a lower temperature environment for the freshly rewound stator. I don't know enough about rectifiers to know how the non-shunt version works, so I just take what they say about the serial ones on face value.

Once the rotor is re-made, reassemble the bike with it and the new rectifier and hopefully never do this again.

 

[Dr. Montano]

Many thanks again. Yes, the option definitely is the OEM part, even though it is expensive, because of the new design. My mistake the first time was to rewind the original. The new design is a major change for a reason. OEM part is expensive, but it includes the whole new design alternator. Regulator-Rectifier will be changed also and it seems the one indicated in the first post does also reduce stress on the stator.

 

[Convince Me]

Many time when an alternator fails it is recommended to install a new regulator. The thinking is the regulator may have contributed to the failure. I have not read all the information you have cited yet but will. This is just thinking out of the box. I can't remember if your alternator showed sighs of mechanical issues causing the failure?

I install a new rotor (cover) also.

 

[tvguy]

""Question No. 2: ¿Can the stator with 21 poles replace the stator with 15 poles inside the original casing (rotor)? It seems not, but if so: Have you actually done it and is it working correctly? (This was a question that I have not found clearly resolved. Lolo28fr in post #146 of the previously referenced thread seems to have tried an RMStator (21 pole) to replace the original (15 pole) and failed.)"""


In our experience the answer is NO... After doing TWO alternator replacements. The first was a 21 pole from Canada. We tested it and confirmed it was ok. It did not work because the system is not designed for 21 poles. The magnets and the spacing between them is off. Had to remove entire engine AGAIN and put in a $1200+ BMW unit. We also saved a ton of time by taking the engine to the dealer and had them install because they had the specialty tools to get it done very quickly. Also replaced the voltage regulator shortly after that.

 

[Dr. Montano]

Yes, the OEM part is the complete alternator, stator and rotor. Will be changing the R/R also. Thanks TVGuy for clarifying this: Specific. Now I have to save up or maybe get a mortgage, but it will be done... Your comments and info have been of great help.

 

[Wazza]

I would not use a cheap chinese alternator. They are not going to be built to the same standard as the BMW product. My education and work experience is in the electrical field. For how much work it is to change, I would not trust any of these cheaply built electrical components.

I have to agree with you. I am also in the electrical field and used to rewind electric motors and I know what it takes to make a motor that lasts. Good insulation is key and a lot of that comes down to how well the windings have been varnished and cured. I am yet to see a Chinese electric motor that has any where near sufficient varnish penetration of the windings and laminations to justify the amount of money you THINK you are saving by going Chinese.

 

[tvguy]

I have to agree with you. I am also in the electrical field and used to rewind electric motors and I know what it takes to make a motor that lasts. Good insulation is key and a lot of that comes down to how well the windings have been varnished and cured. I am yet to see a Chinese electric motor that has any where near sufficient varnish penetration of the windings and laminations to justify the amount of money you THINK you are saving by going Chinese.

Good insulation is absolutely key... BMW had a rash of very poor stators. The upside to the kidney selling BMW unit is it comes with the rotor so the entire unit is complete.