Author Topic: No charge state  (Read 1290 times)

Offline K75user1979

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No charge state
« on: June 09, 2024, 08:09:51 AM »
After having aligned the alternator monkey nutz correctly, the rattling noise was completely gone and all back to normal so I thought.

Went for a long-ish test ride yesterday and all was good until the bike started to run more and more erratically till the point it was back-firing and surging. Stopped, tried to start it but no-go.. battery kaput. 

Luckily I was on a downhill slope so roll started in 3rd no problem but had a hell of a time nursing her home..  I had to leave the lights off and not use indicators at all, even using the brakes would cause the engine to quit.    Battery had just enough juice to keep her running until 300m from home she gave up completely.   It's a heavy bike to push, even just 300m.

Realised the battery warning light hadn't come on at all since putting it all back together and I never bothered to check since the alternator worked perfectly before, brushes are good etc.. not sure about the diode.    The battery light on the dash is not lighting up at all like used to, maybe the bulb is blown??  What else in the circuit could be causing a no charge state?   

Before I did any work on the alternator, it was all working perfectly. 

To add, all I did to the alternator was change both bearings whilst I had it out to change the shaft seal.


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Offline bitsa

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Re: No charge state
« Reply #1 on: June 09, 2024, 09:27:25 AM »
Ignition on (battery recharged of course!) check for voltage on the blue wire to the alternator, or ground the wire to the engine case and see if the lamp lights.  If no power/no light then I'd check for damage to the wire since it's not often you run across a coincidence when working on anything.  If you do see power/light when the wire is grounded then I'd suspect either an internal issue with the regulator or a bad ground somehow between alternator/bike.
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Offline frankenduck

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Re: No charge state
« Reply #2 on: June 09, 2024, 09:54:57 AM »
With the ignition on but bike not running there should be 0V at the blue wire.

The charge bulb has bike main 12V of the bike at one terminal and the blue wire from the alternator at the other terminal. When the alternator is not running (or not charging) there's 0V at the blue wire so the light is illuminated. When the alternator is working there's a nominal 12V at the blue wire so the difference in voltage across the charge bulb is zero-ish so it goes out.

It could be that the bulb is out but that is a pain to get to on a K75S and it would be awfully coincidental for that to happen right after you worked on the alternator.

At least here is the US, you can take an alternator to some auto parts stores and they will spin it up to test it for free.
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Offline rbm

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Re: No charge state
« Reply #3 on: June 09, 2024, 10:20:44 AM »
A good reference guide to read to understand the charging circuit is Charging Around the Circuit.  It's aimed at Moto Guzzi owners but the description holds true for the K-bike since they talk about the Bosch alternator.  Definitely a burnt out charge indicator lamp or a LED inserted in the circuit in the wrong direction will cause the alternator to not charge the battery.
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Offline K75user1979

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Re: No charge state
« Reply #4 on: June 09, 2024, 11:48:24 AM »
Thanks yes I've been researching and found that the most likely culprit is the dash bulb which is needed for resistance.   I noticed that when I was limping home, if I kept the revs up, the alternator would self excite due to residual magnetism.  Man did it kick up a fuss riding with an almost dead battery, it was not fun.  I couldn't use my indicators, headlight or brakes where I could help it.. thankfully dodged the traffic cops.  Also, the only reason I made it within spitting distance of home is for the convenient fact that one can turn off the headlight on these old bikes.

I may pop into my local bosch agent and they will test the alternator although at this stage I'm going to start stripping the dash, something I haven't done before but I'm keen to learn every aspect of this bike..  Clymer manual on stand-by.

As a last note:  I beefed up the dash a bit to stop it wobbling so much, maybe that caused the bulb to die due to less dampening of vibrations.  Co-incidental yes, but I have to rule it out. 

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Offline rbm

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Re: No charge state
« Reply #5 on: June 09, 2024, 12:10:33 PM »
Are you running a regular incandescent bulb as the charge indicator lamp or a LED bulb?
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Offline frankenduck

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Re: No charge state
« Reply #6 on: June 09, 2024, 01:07:58 PM »
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline frankenduck

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Re: No charge state
« Reply #7 on: June 09, 2024, 01:11:37 PM »
Many LED lamps these days are non-polarized. Back in 2008 when I first started putting LEDs in the cluster they were still polarized but for the last 10 years or so they've been non-polarized.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline K75user1979

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Re: No charge state
« Reply #8 on: June 09, 2024, 01:36:17 PM »
Ok, just tested the bulb (incandescent) and it works which is a dissapointment.. was hoping all that effort would have yielded a blown bulb.  Anyway, have ruled that out.   Anything else I should do whilst the cluster back cover is off?     

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Offline rbm

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Re: No charge state
« Reply #9 on: June 09, 2024, 01:58:11 PM »
As was mentioned by @Bitsa earlier and in the reference I gave, the charge light has one side connected to 12V (inside the cluster) and the other side to the alternator through the blue wire.  I'd turn on the ignition but not start the bike and then check for 12V at the end of the blue wire after disconnecting it from the alternator.  If you have 12V, then that means the alternator is getting its activation current feed and likely there is a problem with the alternator/rectifier/regulator which you can get diagnosed at the automotive place.  If you don't get 12V, then there is.a connectivity break somewhere in the cluster, or in the cluster pin 9 or the blue wire.

Also look at the large gauge red wire going to the battery to make sure it is intact. I once had a break in that wire on my bike but you could not see the break because it was hidden under the heat shrink covering one of the spade connectors.
  • Regards, Robert
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Offline K75user1979

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Re: No charge state
« Reply #10 on: June 09, 2024, 02:47:09 PM »
Really appreciate the amazing and helpful replies.  I just looked at the 'Charging around the circuits' document, what an incredible resource and I will certainly learn much from it. 

Will next check blue wire voltage and check continuity of that wire. 
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Offline frankenduck

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Re: No charge state
« Reply #11 on: June 09, 2024, 10:06:06 PM »
FYI: The blue wire is PIN 9 of the instrument cluster connector.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline K75user1979

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Re: No charge state
« Reply #12 on: June 10, 2024, 04:15:37 AM »
Got it.   There is continuity back to connector.  This eve will check for 12v.  In the meantime will have alternator tested.
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Offline Laitch

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Re: No charge state
« Reply #13 on: June 10, 2024, 01:19:23 PM »
Verify that your battery's 12V connection is clean and tight
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Offline K75user1979

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Re: No charge state
« Reply #14 on: June 10, 2024, 01:27:10 PM »
Just tested the blue line with ignition on.  Affirmative 12v.  I like this narrowing-down process, it has to lead to a conclusion soon.

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Offline K75user1979

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Re: No charge state
« Reply #15 on: June 11, 2024, 09:07:52 AM »
One info tidbit I haven't mentioned at all is that I used di-electeic grease on the Alt connector, a liberal amount.   I also cleaned all parts of the disassembled alternator with a weak Solvent and rinsed multiple times with water.    The only part of the alternator I didn't clean or rinse was the voltage regulator, the external part with brushes attached.   

I hope the Solvent or water hasn't ruined internals.   
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Offline K75user1979

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Re: No charge state
« Reply #16 on: June 11, 2024, 09:09:59 AM »
Local auto-electrical bosch service center has changed ownership and they don't do testing or repairs of alternators anymore, dangit!!!   

I have some other tests up my sleeve which will further narrow down the issue. 
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Offline Laitch

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Re: No charge state
« Reply #17 on: June 11, 2024, 09:27:30 AM »
Water wouldn't have been my choice for cleaning an alternator and could definitely be interfering with current flow but you seem capable of diving back inside to clean up and assess again. Open it up and let it air dry away from humidity.
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Offline K75user1979

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Re: No charge state
« Reply #18 on: June 11, 2024, 02:16:08 PM »
Probably not my greatest decision although my thinking was that without power going through electronics, didn't think liquid might get into something sensitive.  Another test I did earlier confirmed bad diodes.

With the engine running and alt connected, I measured ground to small pin, got 12.02v, ground to large pin resulted in 11.5v.  The connector has a flap that opens at the back allowing for probing of contacts.   

If the voltage is out by just the slightest margin, then diodes are bad. 

I've wasted much time testing this and that all the well knowing that it was the alternator all along.   All part of the learning process.

Will revert back here with good or bad news when I get the replacement part installed and test it again.

 

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Offline K75user1979

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Re: No charge state
« Reply #19 on: June 12, 2024, 06:21:20 AM »
Where would be the best place to source another alternator?

I destroyed current one, don't ask. 

Turns out that popping diwn to local Autozone would be fruitless.   Thought they were an off the shelf item like apples, facepalm.

Will have to source overseas, US or Europe or who has one to sell?   

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Offline frankenduck

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Re: No charge state
« Reply #20 on: June 12, 2024, 06:45:31 AM »
Is it a 32 amp alternator or 50 amp?



There's plenty of alternators for sale on Ebay.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline K75user1979

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Re: No charge state
« Reply #21 on: June 12, 2024, 07:03:30 AM »
32amp.  I just realised that im on the Facebook group for k bike owners south africa.  I should get lucky there.  Will exhaust local options then look across the pond.

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Offline Past-my-Prime

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Re: No charge state
« Reply #22 on: June 12, 2024, 10:01:20 AM »
I destroyed current one, don't ask. 

Come on . . . Fire? Water? Mis-connected? Sledgehammer? Dropped from a great height? Lightning?

Just so you know, I’ve used all of the above (and more) to destroy various mechanical devices.

Or keep us guessing, of course.
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Offline K75user1979

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Re: No charge state
« Reply #23 on: June 14, 2024, 06:43:28 AM »
When trying to remove the rectifier board with the diodes, I mangled one of the screws..  easy fix but I got rough with it and pried/ripped it out whilst twisting off the wires.  Part of the alternator got airborne too.   The rest is fine structurally just not sure about the windings which I soaked in mild Solvent and water initally when i took it apart. Sometimes my desire to have things clean sets me back.  Figured it would be easier to replace the entire unit over chasing problems.   A friend of mine found one the next day in the neighboring town, a garage full of k75 bikes..  what a find.  So this guy will be a great source of future parts needed.  He's dropping off the alternator today, hoping it's mechanically/electrically sound.
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Offline K75user1979

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Re: No charge state
« Reply #24 on: June 15, 2024, 03:33:19 PM »
Well..   I finally got hold of an alternator.   I didn't even have the patience to clean it up properly so it went in with dirt and all, I was just keen to test it.  It came with the cup and monkey nutz which of which I have spares now.  To get the alternator back in, I first rotate the vanes engine side so that one faces up, you can do it by hand.   I then mark a line on the cup to indicate how it must be orientated for the monkey nutz to align correctly.  I then get the alternator in place and rotate it to correct orientation for its mounts and connector.  I then rotate the cup so that the line is on top and then just slide it in, easy as that.

Fitted the rest, buttoned her up and turned the ignition to on and voila!!!   the battery light came on.  Started her up and as the revs came up the light went out, good sign.   Measured 14v on the batt terminals, back in business. 

Took her for a test ride to visit my brother and fiancee.  Running as smooth as ever.  I have other bikes to ride but this one has been my go to bike since I restored her end of last year, I just love riding it.

Thank you all for the excellent advice.  Case considered closed.
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