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jambo
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VBMWMO #9208
Long Island
Joined: 11/23/2016
Posts: 122

Hello, I am trying to figure out why my new R51/3 is not charging the battery and I am starting to run some diagnostics. I got the "understanding and maintaining the BMW /2 electrical system" paper and was about ready to start diagnosing when I got to the part of trying to measure resistance from D+ to F-. The picture in the paper and my regulator look completely different and I am sure I have an older version. What I THINK is D+ and F- measure out to be .7 Ohms, not 2.5 to 4 Ohms. I wanted to check to see what others thought and have pictures below of mine.

Any help is appreciated!

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James W.
1967 R69S, 1966 R50/2, 1965 R27, 1963 R27, 1952 R51/3 and 2018 R1200GS

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
Posts: 596
Charging system

jambo wrote:

Hello, I am trying to figure out why my new R51/3 is not charging the battery and I am starting to run some diagnostics. I got the "understanding and maintaining the BMW /2 electrical system" paper and was about ready to start diagnosing when I got to the part of trying to measure resistance from D+ to F-. The picture in the paper and my regulator look completely different and I am sure I have an older version. What I THINK is D+ and F- measure out to be .7 Ohms, not 2.5 to 4 Ohms. I wanted to check to see what others thought and have pictures below of mine.

Any help is appreciated!

I think I have the older regulator in my r51/3
I will check tomorrow

Did it ever work or just stop charging?

The D+ terminal is one of the yellow wires coming out the field coil and is connected to the top brush and also to the blue wire for the charge light
The other yellow wire is the Field wire going to the regulator

The low reading you are getting is because the commutator and charge light is in parallel with this and at least one of the field windings needs to be disconnected

The statement to measure resistance from D+ to F is misleading as it does not say to separate one of the field wires (it is assumed that you allready have the field coils are out of circuit and to be tested only with no parallel resistance

I will verify this tomorrow

To bypass the regulator you can disconnect the field wire to the regulator and ground it and the charging should put out max voltage

looks like your regulator is cooked and the burn spots on the commutator indicate the that you may have a bad armature The test from "understanding and maintaining the BMW /2 electrical system" only shows the commutator is not shorted to the armature and between each segment on the commutator is .1 ohm not 0 ohms

If your brushes are in good shape and the regulator is bypassed and passes the commutator test then its likley you still may have a bad armature

This only be tested by a Growler which introduces a magnetic field into the armature to see the current is not shorted to the outside of it and going only to the commutator contacts to produce a output to the regulator and then to the battery and load

Any good electrical shop should have one
Sadly most don't today as it is a plug and play world

I do have one and can test the armature if needed
Phone
413 628 3958

Tommy

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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

jambo
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VBMWMO #9208
Long Island
Joined: 11/23/2016
Posts: 122
Thank you!!

I am going to keep testing the system and am learning all about the mechanical regulator. I will be an expert by the time I am done. Thanks for your help and wisdom!!!

__________________

James W.
1967 R69S, 1966 R50/2, 1965 R27, 1963 R27, 1952 R51/3 and 2018 R1200GS

808Airhead
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VBMWMO #7677
Joined: 08/05/2009
Posts: 1025
Clean the points,and with key

Clean the points,and with key on play with the points and see if the charge light illuminates,make sure you see the charge /field light working. I had a same old regulator setup on my 1951 R51/3 and after playing with it for hours,taking it apart,cleaning it up,playing with points adjustment,I gave up on its 50+ year old headaches and bought a electronic regulator from Germany for around 80 bux and it is wonderful. I have the same regulator in my R69S,and it fits,easy to install and works perfectly.

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Thomas M.
R69s - R60/2 - R67/2 - R51/3

Micha
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Joined: 10/12/2007
Posts: 352
Same here. Bought my charging

Same here.
Bought my charging system over at powerdynamo, and since then never looked back.

__________________

Michael Steinmann
R51/3 1952
Engine Nr. 529466

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