Author Topic: Alternator Charge Light  (Read 1686 times)

Offline Bob_Roller

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Alternator Charge Light
« on: June 30, 2013, 02:15:14 AM »
Worked a double shift today, 0600-2300, on the way home I noticed that the  charge light was glowing dimly on the Guzzi .

Can't find my Boxer charging system manual from Motorrad Elektrik .

The Guzzi uses the same Bosch charging system as the airhead BMW's .

From memory, the most common causes are, worn brushes and diode board .

The Guzzi has 21,000 miles, so I don't think the brushes are worn to the point that they would cause an issue .

Looks like I need to remove the diode board from the parts bike, '84LS, for trouble shooting .

I ordered a higher voltage regulator from Motorrad Elektrik about 3 weeks ago, due to the low voltage output of the Guzzi's charging system .

That didn't seem to improve the output voltage on the volt meter in the instrument cluster .

Was seriously considering ordering an after market diode board at the time, but didn't .    ;D ;D ;D ;D ;D ;D
« Last Edit: June 30, 2013, 11:47:56 AM by Bob_Roller »
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline nhmaf

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Re: Alternator Charge Light
« Reply #1 on: June 30, 2013, 09:06:45 AM »
It could be a corroded connection at a voltage regulator teminal, or bad/dirty connection from the alternator to the diode board (or for that matter, (1) bad diode on the diode board would cause the charging voltage to be low as well).

Hopefully your Guzzi project doesn't turn in to my BMw project!


Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Offline Bob_Roller

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Re: Alternator Charge Light
« Reply #2 on: June 30, 2013, 11:47:38 AM »
Thanks Mike .

If I hadn't been riding in night conditions, I never would have noticed the light being on, in daylight, it's not noticeable at all .

I went through all of the connections on the bike that didn't require serious disassembly and found no corrosion or dirty, loose connections, when I was on vacation last year .

It's been an Aridzona bike from new, no corrosion any where on the bike .
« Last Edit: June 30, 2013, 01:26:18 PM by Bob_Roller »
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline nhmaf

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Re: Alternator Charge Light
« Reply #3 on: June 30, 2013, 02:06:14 PM »
Probably more likely that the voltage regulator died like mine just did last week!  But, don't discount the possibility of vibration induced connection looseness.

What voltage are you measuring at the battery when the engine is running ~4K ?   Generally if a diode fails, the drop in voltage is severe enough that the GEN light gets pretty bright (though in the Aridzona sun, NOTHING is bright enough in comparison!!)
Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Offline Bob_Roller

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Re: Alternator Charge Light
« Reply #4 on: June 30, 2013, 02:34:13 PM »
I just checked the voltage this morning, 13.1 volts with all of the lights off, there's a switch to turn all of the lights off on this bike, I have been told the bike shouldn't have this, only European model bikes had this feature .

With lights on, 12.4 volts .

I'm not so sure I'm going to get to this today, it's 1230 and the temp is already 110 F (43C) .

On Friday and Saturday I worked double shifts, most of it outside at the passenger terminal .

It's the first day of my weekend, I don't think I'm going to much outside of an air conditioned environment !!!!!!!!!!!!!!!! :D :D :D :D :D
« Last Edit: July 02, 2013, 06:47:47 PM by Bob_Roller »
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline Bob_Roller

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Re: Alternator Charge Light
« Reply #5 on: July 02, 2013, 06:35:56 PM »
Temperature moderated a bit today, only 105 F (41C) in the garage this afternoon, when I got home from work at 1500 .

Removed the diode board from the Guzzi and tested it .

One diode gave me a reading that I don't quite understand, the LCD in the multimeter, would give a numerical value, then go to dashes that were flashing, then back to numerical value, constantly cycling .

So I decided to remove the diode board form the '84LS 'parts' bike .

Installed it on the Guzzi and now I have 13.5 volts at 4500 rpm with a full electrical load and the charge light is not on dimly anymore once it goes off at 1500 rpm .

A parts bike is indispensable at times !!!!!!!!!
« Last Edit: July 02, 2013, 06:37:07 PM by Bob_Roller »
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline nhmaf

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Re: Alternator Charge Light
« Reply #6 on: July 02, 2013, 07:26:13 PM »
If the battery in your multimeter is good, it sounds like either the diode is cracked or there might be an intermittent solder joint, depending on where you physically had the probe ends.    If you can get individual diodes for it (the power diodes are not a corner radioshack item though) you could probably fix it, but it is probably just as well to spend some bucks and get a nice new unit from Rick @ Motorrad, or other source of your choice.

It is nice having a "backup" machine - I was swapping plugs and plugwires between my R100 and R65 this past weekend -- and determined I had an intermittent plug wire on the R100.   Now new plug wires and new plugs and it is running much better - just have to get around to re-synching the carbs..
Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Offline Bob_Roller

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Re: Alternator Charge Light
« Reply #7 on: July 02, 2013, 08:11:24 PM »
With the July 4th holiday on a Thursday, I'm taking the Guzzi to work three days this week, Thu-Sat .

So, I'll see if I get any improved headlight brightness, it was quite 'dull' on my way home Saturday night .

First time I've ridden the bike in night conditions, if this doesn't improve the lighting, I'm getting a separate harness and use a relay for the headlight .
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline montmil

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Re: Alternator Charge Light
« Reply #8 on: July 03, 2013, 09:48:12 AM »
Hmmm...

Just wondering how easy it might be to convince Wifey that a "parts bike" would be a smart purchase.

Y'all think she might see some differences twixt my three Airheads and a late-60s Triumph?

Monte Miller
Denton, TEXAS
1978 BMW R100S
1981 BMW R65
1983 BMW R65
1995 Triumph Trophy
1986 VW Cabriolet

Offline montmil

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Re: Alternator Charge Light
« Reply #9 on: July 03, 2013, 09:50:52 AM »
And speaking of voltage regulators. I do love the solid-state VR that Rick Jones offers. The battery likes it, too.
Monte Miller
Denton, TEXAS
1978 BMW R100S
1981 BMW R65
1983 BMW R65
1995 Triumph Trophy
1986 VW Cabriolet