Charging Light

[blackcat]

The charging light on my CX(Lemans II) Bosch system stays lit until about 2,000 RPM + or - but it is charging. I have removed the alternator cover to watch the brushes and they sort of bounce around quite a bit and I’m wondering if I should just replace the brush holders as they are about 12-15 years old. Springs are tight and plenty of meat on the brushes. I also installed an adjustable voltage regulator but that doesn’t seem to be changing much of anything.  My other problem, and I think that I solved the issue is that on longer trips the battery is  getting worn down, but since I rotated the brushes from 9 o’clock to 12 o’clock,  gravity is helping the issue but I haven’t taken the bike for a long ride. Everything is grounded, all connections are clean and Deoxited. I haven’t polished up the rings but they look pretty clean.

[Kiwi_Roy]

I wonder if the rotor is not sitting on the crankshaft taper properly, if its out of round the brushes might be bouncing and losing contact.
The key might be too large and holding the rotor out of centre., Perhaps set a dial gauge and rum on the shaft then run it again on the slip-rings.

I found on my California II that if I cleaned up the slip-rings with a dry cloth the alternator would produce more current for a while, I think the brushes would make better contact for a while.
I would also check every diode in the rectifier in case there's a couple of bad ones.

[nc43bsa]

It's been a while since I worked on a Bosch alternator of that type, but if the brushes are "bouncing" I'd check to see if the slip rings are out of round or the rotor is not straight on the crankshaft.

Either can be verified with a dial indicator on the slip rings.

[Muzz]

My thoughts much the same, something is out of round/not true if the brushes are bouncing.

[blackcat]

I will pull the rotor and see if I can reposition it on the shaft. The seal was replaced about a year ago and maybe I did something wrong when I re-installed as there wasn’t a problem when the rotor was replaced a few years ago. Thanks

[Chuck in Indiana]

It's hard to get wrong unless there was an unnoticed burr or piece of dirt on the taper.

[Antietam Classic Cycle]

The key might be too large and holding the rotor out of centre.

No key on the tapered nose cranks/Bosch charging systems.

[pehayes]

What is your battery status?  Age?  Overnight standing voltage?
The system has to use battery input to 'boot-strap' and begin to generate more than it consumes.  Beginning with a weak battery may  mean higher rpm to generate a charge.
What battery technology?   AGM batteries have a slightly higher standing voltage and this helps to begin the charging function earlier.  Find a good AGM and just jumper cable to your bike.  See if it generates earlier or at lower rpms.

Patrick Hayes
Fremont CA

[wirespokes]

The service limit for brushes is something like 16mm new, half that - replace.

If you have to, you can run them longer, but tension on them goes down the shorter they are.

Try shimming them to get a bit more spring tension, that might be all you need. Until replacements arrive.

And do measure them - that's the best way to tell, but if the spring is getting close to bottoming on the plastic holder you know they're getting short. I've seen the rear brush wear significantly more than the front one, so don't presume they're both in the same condition.

Someone came up with a way to attach the brushes without having to remove the stator. By attaching a ring terminal on the end of the lead no soldering is necessary.

This problem does sound like the classic 'brushes almost all worn out' symptoms.

[TOMB]

Disconnect the clock. Its running all the time and if you don't ride often your starting off with a low battery.

Also the volt meter isn't one on the best takes to long to register what the charging system is doing, if you insist that you need a voltmeter search the web and find one with a more sensitive movement..

TOMB

[John A]

There was a service bulliten to position the brushes at 3 or 9 oclock,  dont remember which,  to prevent road bumps from causing brush bounce.

[blackcat]

Battery status is fine as I swapped out another battery with the same results.

Brushes were at 9 and I moved them to 12 with better charging results. Short runs at 9 were showing 12.7, moved to 12 and I’m now getting almost 13.

I have to measure the brushes, but a quick look says they are OK but it might be a problem.

Can’t work on it today, but will pull everything tomorrow night and report back with what I have

I do have another rectifier, so maybe I should just put that in, but i’ll try the basics before doing that work.

No clock, just the basics and the Dyna ignition.

[Chuck in Indiana]

FWIW, I was getting low charging on the AeroLario the other day, and it was a weak crimped connector on the yella wires.

[blackcat]

FWIW, I was getting low charging on the AeroLario the other day, and it was a weak crimped connector on the yella wires.

I will check it out, but the wiring is a fairly new Greg Bender harness.

[Antietam Classic Cycle]

If you don't have one already, the addition of Greg's "bootstrap harness" may help. Really seemed to help on my Convert, along with the solid state adjustable voltage regulator.

[blackcat]

If you don't have one already, the addition of Greg's "bootstrap harness" may help. Really seemed to help on my Convert, along with the solid state adjustable voltage regulator.

What exactly does the bootstrap do?  I already have an adjustable VR. 

I have no idea how long the brushes are suppose to be but these look short, maybe not.



Cleaned up the rings after this photo, have continuity but unless I’m doing something wrong which is quite possible, I keep getting a reading of 2.5 ohms and it is suppose to be 3.4 ohms.

[Muzz]

A lot of brushes have a score mark on the face to indicate maximum wear.  Don't know whether Guzzi do this though.

[Antietam Classic Cycle]

What exactly does the bootstrap do?  I already have an adjustable VR. 

Eliminates the need to have the warning light working, seems to improve charging - more volts at lower rpm.

[wirespokes]

The front brush looks good - probably 16 or 17mm. New is around 18mm. Be sure to check the other one in the rear - it tends to wear a lot more than the front one.

Another possibility is spring tension. I seem to recall a whole turn is needed, but I'll check. Yes - that's the data I have - when brushes are new, the spring will be almost one whole turn. The one I see appears to be a half turn. That could be it right there.

[jacksonracingcomau]

Those brushes are not the problem
Just maybe (seen it once, twice or a thousand times but no promises)
Clean the inside of stator
You say you changed the seal, if oil gets on inside of winding it stops it working (as does brake fluid)
Wet alternators are somehow different
Spray with contact cleaner until eat yer dinner off clean, try again
Best

[chuck peterson]

I've seen the springs bottom out from what looked like not worn brushes...new brushes solved 3 years and 20k miles of charging issues on a friends LeMan V...at a short glance it looked fine, but the bottomed spring is hidden from view....whole new bike and a whole new confidence level

[Furbo]

If you're going to take the time to pull the rotor, put in a Euro Moto electrics charging system and never look back.

[blackcat]

Eliminates the need to have the warning light working, seems to improve charging - more volts at lower rpm.

Thanks Charlie, wish I had known that when the harness was replaced.

[blackcat]

Those brushes are not the problem
Just maybe (seen it once, twice or a thousand times but no promises)
Clean the inside of stator
You say you changed the seal, if oil gets on inside of winding it stops it working (as does brake fluid)
Wet alternators are somehow different
Spray with contact cleaner until eat yer dinner off clean, try again
Best

Yes, the inside was a mess and I’ve cleaned it but it is still a bit grungy.  Brake cleaner OK?

I cranked up the springs, maybe that will help.

I’m not against spending the $500 bucks on the Moto electrics unit if this was my only bike and I was running full suit electrics but that isn’t the case. The last time I had charging problems on the bike was a dozen or so years ago so I’m willing to wade through whatever is the problem. I’m now starting to think the oil coated stator is the problem.

[wirespokes]

The oil could be contaminating the brushes and their contact with the slip rings. I had an older airhead that sat unused for a long time. The brushes looked good, but had left a black coating on the slip rings. It stopped charging and left me stranded. Cleaned the slip rings and all was good. I'd maybe even use Gunk or kerosene or Greased Lightning or Simple Green to clean it up. For a final clean up, use the brake clean.

[blackcat]

The oil could be contaminating the brushes and their contact with the slip rings. I had an older airhead that sat unused for a long time. The brushes looked good, but had left a black coating on the slip rings. It stopped charging and left me stranded. Cleaned the slip rings and all was good. I'd maybe even use Gunk or kerosene or Greased Lightning or Simple Green to clean it up. For a final clean up, use the brake clean.

I’ve cleaned it up with Simple Green, just going to spray it down with brake cleaner and see what happens.

[jacksonracingcomau]

Be very careful with brake ( not break) cleaner, some is not so clever, contact clean or alcohol safer.

[blackcat]

Be very careful with brake ( not break) cleaner, some is not so clever, contact clean or alcohol safer.

Yes, brake. 

Well, everything is back together, the light goes off much quicker than before and it easily reaches 13.2 at the usual rpm’s but I will see what happens tomorrow after a longe run at a sustained higher speed(s). The light still glows at idle, but I forgot to adjust the VR, so maybe that will solve that issue.

[Antietam Classic Cycle]

Thanks Charlie, wish I had known that when the harness was replaced.

It's a simple little harness - just a wire with resistor - that can be added at any time.

Rectifier to fuse panel

Connects the rectifier to fuse number 5 to bootstrap the charging system. Comes complete with 2 watt, 82 ohm resistor soldered in place (as original). $6.75

[wirespokes]

All the resistor is doing is bypassing the charging light. The light will still come on normally and let you know if something aint right, but if the light blows out, the alternator will still charge. When the alternator is charging and the light goes out, no current will be going through the resistor, so it won't get hot. The alternator may even start charging at a lower RPM with the resistor.

I don't know that any of my bikes with the Bosch charging system have charged at idle. The light is always on at idle, but it doesn't hurt anything.