the red GEN light not coming

[R65LS]

my 1982 R65LS ... the dreaded electrical problems about which I know nothing.

The problem:  no red GEN light when I turn the key ON but before I push the START button.

I read this:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1189776513

BACKGROUND:  I didn't pay attention and let the battery water level go way down in a couple of cells.  Perhaps I fried the battery by doing so ??
Last night I filled and charged the battery for 4 hours.  This morning the bike fired right up, no problem.  I took a 35 mile ride.  When I was 1/2 mile from home, all of a sudden the bike backfired and quit running, none of the instrument lights were ON, battery apparently/obviously dead.  Pushed it home and into the garage (I'm a very lucky guy).

The bike sat for 2 hours.  I just checked it.  Turned the key ON and the Neutral light came on as did the Oil light but not the Gen light, I guess some spontaneous battery charging ??  I pushed the Start button and there is enough battery juice to spin the starter and push the solenoid a tiny bit forward to do the click-click-click.
 --  as best I know, all normal for a bad battery .... Except no GEN light !!

Is it possible:  by not watering the battery properly I put too much draw on the alternator and burned out the alternator ??

Also, what I don't know:  if the red GEN light was lit this morning.  I wasn't paying attention.  I only know that tonight it does not light up.

Tomorrow I'll pull out the GEN bulb to determine if it is burned out.
And I have a brand-new battery I will install to see how it affects the system.

Any and all help is appreciated to figure this one out.

Cheers,

Carl

[bruce_launceston]

Fit the new battery but before riding the bike and potentially draining and killing the new battery check to see if it is charging.
Put a multimeter across the battery terminals, set it to DC Volts, usually <20, some are auto range finding.

You should have just over 12 volts with the motor off, with the motor running above about 2,500 rpm I guess there should be about 14 volts. If not there is a charging problem.

Obviously if there is no gen light there is no charge, even if it's only a blown globe I believe the charging circuit will be open and not charging.

[Barry]

I didn't pay attention and let the battery water level go way down in a couple of cells.Perhaps I fried the battery by doing so ??

Once the battery plates are uncovered they tend to sulphate very quickly which will ultimately kill the battery.  You can get away with it if the level is only slightly low as in use the electrolyte will be splashed around a lot. My battery needs topping up regularly but that's because I have deliberately set the voltage regulator to a high setting of 14.4 volts to help with predominantly short commuting runs which would otherwise run the battery down. It will be interesting to see what charging voltage you have as a result of the test Bruce described.


If the charge light does not come on with the ignition switched on your charging system is not going to work. The alternator exciter circuit passes battery current through the bulb, voltage regulator and rotor to earth. No light means there will be no exciting current passing through the rotor so there will be no alternator output. Hopefully it's a blown bulb or bad connection somewhere otherwise it could a failed rotor.

To test the rotor put small pieces of card between the brushes and the rotor slip rings to isolate it from the charging circuit. Then measure the rotor resistance with a meter. I forget the exact value but if it's something like 3 or 4 ohms the rotor is good. Meters are usually not that accurate to the nearsest ohm anyway when measuring low resistance. If the rotor has blown you will read open circuit ie very high or infinite resistance.

If the bulb is good and the rotor is good then the voltage regulator might be faulty. At least they are cheaper than a rotor.

[tvrla]

How many miles on the bike?

No, the battery problem didn't kill your alternator.

The battery didn't get charged as it should and ran down - that's all. Also, it takes more than four hours to recharge a discharged battery. You are trickle charging it, right? Set it on the 2 amp setting, no higher. It could take overnight to bring it back up to full charge.

Grounding either of the alternator brush terminals DF or D- should turn on the light. If the DF turns it on, but not the D-, then the problem is somewhere between the two - either the brushes or the rotor.

By shorting the two slip rings together (screw driver, coin...) the light should then come on. If it does you'll know the rotor is bad. If not, it could be the brushes or the rotor.

The ohm meter will tell you if the rotor has continuity or not - and if it does, then it's most likely the brushes - either worn or hanging up in the guides.

Word of warning - disconnect the negative battery terminal before removing the front engine cover! It's possible to contact the plus side of the diode board with the cover while removing it and short it out

[Bob_Roller]

Once you get this problem sorted out, there is a quick simple modification that can be accomplished to make a burned out light bulb not a real issue .

You need to solder a 5 watt 330 ohm resistor between the two wires of the GEN light circuit .

It won't make the light keep working, but it will keep the charging system operating as if the bulb were still good .

[R65LS]

67,000 miles on the bike.

WOW !!  Thank You all for all this info !!

I'm naturally hoping it is as simple as the dash bulb being burned out ...

Cheers And Thanks,

Carl

[Bob_Roller]

With 67,000 miles on the bike, this is assuming it hasn't been done yet, check the length of the brushes on the alternator .

Mine were worn to the point that the red GEN light started glowing dimly at 57,000 miles due to the brushes being worn out and short .

[montmil]

With 67,000 miles on the bike, this is assuming it hasn't been done yet, check the length of the brushes on the alternator .

Mine were worn to the point that the red GEN light started glowing dimly at 57,000 miles due to the brushes being worn out and short .

It may be necessary to remove the stator to access the aft brush holder. It's not a difficult chore but do remember to disconnect the battery cables.

You will see the "pig tail" springs that hold brush pressure against the rotor. If the tail is way down inside the brush holder, that's an indication that one or both of the brushes may not be making contact.

Note how the brush holder can interfere with the spring and limit its lower deployment. A quick ghetto check, besides measuring the brush length and comparing to the specs in your manual, would be to trim a couple bits of wood to sit on top of each brush, then refit the spring. Doing this will place the worn brushes in contact with the rotor... hopefully.

Replace the stator, hook up the battery, and turn on the ignition. GEN light on? Brushes likely worn out.

Good luck. Post up what you discover.

[MR.E]

now then

i've still not attempted this yet!!
can you supply a pic of the brushes, i want to get my bike back charging again & monte's last post about the little pieces of wood on the brushes sounds like a good idea.

BUT whats the brush look like??
also this may help some of you.
http://www.ebay.co.uk/itm/BMW-R-65-Stator-brush-plate-id5055-/390357210624?pt=Motorcycles_Parts_Accessories&hash=item5ae31a5600

[Lucky_Lou]

http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=20&Ct=IA&SbCt=BA_15_20_IA_05
Scroll down 3rd item
I think this is what you are after, ring them the are very happy to help out and will give good advice.
Lou

[montmil]

"Brush" is quite the misnomer. The parts are made of a pressed carbon, plus lord knows what else, and have a braided copper 'tail' attached to one end.

The brush holder is positioned just above the rusty-ringer rotor. The ivory-colored, squared fixture. See the "pig tail" spring on the right side of the brush holder? the other end of the 'tail' is pressiing down on the brushes, making contact with the two copper slip rings. The gray-ish wire coming out the top of the brush holder is the wire lead. You can pick out the other brush holder on the back of the stator by following the other gray wire.

A few Allen screws hold the stator in place. Be sure the battery leads are disconnected as there is power under the front engine cover.

Hope this helps you out.

[R65LS]

 I am A-OK with checking the brushes, plenty of mechanical skill for that.
 I was thinking brushes could be the problem (learned all that while fixing my 1948 Chevy truck many years ago).  Will be the first check.

THANKS MUCH for the help and the pictures and such.  I plan to tackle this Monday morning.

Cheers,

Carl

[R65LS]

[size=14]UPDATE ...... UH OH .....  I think the rotor is bad !![/size]


Here is what I did:
1)  turn ignition switch ON.  GEN light on the dashboard is off.
2)  ground DF terminal, GEN light on the dashboard comes on.
3)  ground D- terminal, GEN light on the dashboard stays off.
4)  connect DF terminal and D- terminal, GEN light comes on.

5)  Remove wire leads from DF and D- terminals (this isolates the rotor).
6)  using testing continuity light, connect DF terminal and it's slip ring, this checks the brush continuity to the slip ring.  Light comes on.
7)  using testing continuity light, connect D- terminal and it's slip ring, this checks the brush continuity to the slip ring.  Light comes on.
 connect testing light leads across the DF and D- terminals, light does NOT come on. (the current runs through the brushes and rotor).
9)  connect testing light leads across the rotor slip rings, light does NOT come on.

[size=12]SO, based on all the info y'all provided ..... I would say the rotor is burned out.
 Â Is That Correct ??[/size]


Cheers,

Carl

[Bob_Roller]

Sounds like an open rotor .

Your next step, is to get the rotor removed, an inexpensive tool is necessary to remove it .

I wouldn't try removing it without the tool .

[Barry]

SO, based on all the info y'all provided..... I would say the rotor is burned out.
 Is That Correct ??

Afraid so