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

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.

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.

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.

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.

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.