BMW K bikes (Bricks)

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1Back to top Go down    Charge Light on Constantly on Mon Sep 14, 2015 12:45 pm

veets

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The Red Charge light on my K100RT stays on constantly but the alternator is generating a charge (~13.5 volts at 2000 rpm). I have driven over 600 miles with the light on but would like to find the source if possible. The problem started when I was soaked on my bike and started experiencing some weird electrical issues. The charge light came on and every other gear (2nd & 4th) turned on the "neutral" light. The only numbers that showed up on the display was 1 & 0. After drying out the bike overnight, the "neutral light issue went away" but not the charge light.

I have looked through the past forums but have not found this exact problem. I have tried cleaning the ground connection and the alternator brushes.

Can someone point me to a past discussion or in the right direction?

Thanks,

Veets

    

2Back to top Go down    Re: Charge Light on Constantly on Mon Sep 14, 2015 6:09 pm

Corkboy

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A bit of a long shot, but the only time my charge light glows without reason is if the heated grips were on.
Could be dampness in the heated grips switch, if you have one.


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Regards,

Corkboy '87 K100RS 0140995 (Gone)
'97 K1100LT 0188024
'08 Transalp 700
    

3Back to top Go down    Re: Charge Light on Constantly on Mon Sep 14, 2015 6:10 pm

Holister

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You're looking at 2 separate issues here.

13.5V from the alternator is way too low. Should be around 14V. The battery doesn't start charging till 13.6V. So that's why you're charge light is on.

When the gear position switch (GPS) at the back of the gearbox gets wet it can send false signals to the instruments. Pretty common.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

4Back to top Go down    Re: Charge Light on Constantly on Mon Sep 14, 2015 8:31 pm

RicK G

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This is from a factory service bulletin


You splice in a diode to the blue wire that goes to the alternator with the arrow pointing to the alternator. You would need a diode that is capable of 5 amps. Put heatshrink tube over the wire when you cut it so it can be slid down over the diode and exposed wire after soldering.

This mod is not necessary for the correct functioning of the bike but will prevent the soft glow of the light.

BMW said in a service bulletin that this is a result of a bad connection in the circuit and that is not a warranty item.


The charging voltage should be 14.2 volts at optimum.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

5Back to top Go down    Re: Charge Light on Constantly on Tue Sep 15, 2015 12:01 am

veets

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Gentlemen,

Thanks for your responses.

Corkboy - thanks for the thought but i do not have heated grips

Kaptain Hollister - I rechecked the voltage at 3000 RPM and it is reading 13.6V with the high beam light on. Should it be reading higher? If so, what could be drawing down the voltage?

Rick G - Thanks for the service note! Will this correct the issue if the light is constantly shinning bright? I can see it clearly even with mid-day direct sunlight.

This is a perplexing problem because I have had no difficulties in starting nor have I had to put a charger on the battery.

    

6Back to top Go down    Re: Charge Light on Constantly on Tue Sep 15, 2015 1:42 am

RicK G

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If the light is that bright then you need to look into the charging system.
If you are doing a regular 20 mile run and not to the shop type riding then the 13.6 would probably keep things functioning.
Your battery would slowly degrade and very suddenly all would fail.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

7Back to top Go down    Re: Charge Light on Constantly on Tue Sep 15, 2015 5:15 am

Holister

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veets wrote:.....
Kaptain Hollister - I rechecked the voltage at 3000 RPM and it is reading 13.6V with the high beam light on. Should it be reading higher? If so, what could be drawing down the voltage?
.....
If the light is that bright, your system is not charging properly.

2k or 3k rpm doesn't matter. Voltage output is regulated over about 1800rpm. Nothing is drawing the voltage down, the alternator is not outputing. You can check the brushes which are a part of the voltage regulator on the back end of the alternator but I'd say the voltage regulator is on the way out. Brushes and regulator are one unit and can be easily replaced.
BOSCH - BMW K Internal Voltage Regulator


Sometimes taking the unit out and cleaning it up can make a difference.
You could also check all your earth connections.

If nothing is done you run a big risk of permanent damage to the battery and other components.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

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