BMW R80 charging?

[GOPSTER]

My 1980 BMW r80 won't charge.

It started a few weeks back on a ride, it blew a fuse and a bulb. The battery made it just back into town before running out of juice. I replaced the bulb and the fuse but still no joy. The gen light refuses to go off. I have checked the alternator, diode board and regulator. They all seem to be working, but I don't know what I am specifically looking for from each. I have shorted the regulator and the light is still on. I am using a 14v lithium battery that could be the problem, but it has worked fine for the past 3 months.

What readings should I be getting at the alternator, diode board and regulator?

Any help would be appreciated. I am missing out on the last few rides in the sun

[mossy1200]

My 1980 BMW r80 won't charge.

It started a few weeks back on a ride, it blew a fuse and a bulb. The battery made it just back into town before running out of juice. I replaced the bulb and the fuse but still no joy. The gen light refuses to go off. I have checked the alternator, diode board and regulator. They all seem to be working, but I don't know what I am specifically looking for from each. I have shorted the regulator and the light is still on. I am using a 14v lithium battery that could be the problem, but it has worked fine for the past 3 months.

What readings should I be getting at the alternator, diode board and regulator?

Any help would be appreciated. I am missing out on the last few rides in the sun

The k100 uses the charging light bulb as a resistance that sends a signal to start the alternator.
With my speedo replaced I used a resistor to replace the 1.5watt charging lamp.
Blown charging lamp equals alternator wont do it for you. Same era bike so I would say that's your first thing to look at.

[spanner spinner]

test the diode board first as these are usually the first thing to give trouble see http://www.scribd.com/doc/24846490/BMW-Boxer-diode-board-testing-procedure#scribd for how to do it as it's a rather involved job. the charging system on your bike was only ever designed to charge a lead acid battery, a 14v lithium battery is not a good idea and this could have caused damage as the charging system will be forced to run at a higher voltage and it was not designed to do this.

[GOPSTER]

test the diode board first as these are usually the first thing to give trouble see http://www.scribd.com/doc/24846490/BMW-Boxer-diode-board-testing-procedure#scribd for how to do it as it's a rather involved job.

I had tested the diode board but have just rechecked it following the instructions and it is working correctly.


Mossy I did learn the hard way about the Gen lamp but I have one on there and it is glowing meaning that it isn't charging. Before the other weekend it was working properly.

[mossy1200]

I had tested the diode board but have just rechecked it following the instructions and it is working correctly.


Mossy I did learn the hard way about the Gen lamp but I have one on there and it is glowing meaning that it isn't charging. Before the other weekend it was working properly.

Im running a lithium battery in the k100 also without issues but the alternator wont start until the revs get high enough to activate it. This could be the resistor size that I picked which is 47. I think that equates to 1.5 watts. Quick throttle blip gets it started. Im not having any issues with high voltage. 13.8 volt is the highest I can get out of the alternator and once alternator starts its 13.2 idling.

Maybe short to ground after the lamp. This would cause indicator to go but alternator not to receive start signal.

[Voltaire]

Checked the rotor?
From memory about 3 Ohms
Old brushes sometimes run out of reach too.

My R90s seems to charge its Shorai battery ok.( but its had the mechanical regulator replaced with an electronic one)

[GOPSTER]

Checked the rotor?
From memory about 3 Ohms
Old brushes sometimes run out of reach too.

My R90s seems to charge its Shorai battery ok.( but its had the mechanical regulator replaced with an electronic one)


Brushes are good and the rotor is at 4 ohms

I did find the wire from the diode board to the starter has worn through but have taped it up (will replace) and still nothing. Could this have blown something. I am running out of ideas

[Banditbandit]

My airhead alternator died - all the symptoms you have on yours ...

Have fun here ...

http://bmwmotorcycletech.info/trbleshootalt.htm

(I wound up replacing her rotor and stator ...)