Battery light gets brighter with increase in RPM

[wacky941]

I have an interesting problem with my battery, they put me on the night shift a little while back and so now when I leave work it's dark which is why I'm now aware of this problem.

I have noticed as I ride that if I'm riding at about 35mph (in fifth gear) I have no problem but then if I increase speed to like 45mph I notice that my battery light is at a dim glow, then if I bump it up to about 55mph it is brighter, again this is at night and the glow of the light is visible but during the day it is not visible. The light never gets bright enough that I would be worried that I have imminent failure but it is telling me that there is something not quite right.

What I have noticed is that as the RPM is increased the light gets brighter and of course as the RPM gets lower the light dims out of view and when the light is on maintaining constant speed maintains the brightness level of the light. All my instincts say that the problem is most likely the regulator becoming unstable and having problems maintaining 14.5vdc at the higher RPM's, I don't have a voltmeter that I can connect to the bike and ride it to verify my theory.

I have two questions:
First, am I on the right track with my analysis? Has anyone here had this problem before? I looked in the manual and also on this site and so far haven't found anything that covers my problem.
Second, does anyone here know where I can find a voltmeter that is water resistant and can be permanently mounted to the bike and is not the size of an orange? I've looked at regular automotive meters but none are water resistant and I don't want to wrap it in a ziplock bag.

[tom203]

I can't really help with your first question, but yes, your voltage might be unstable because of r/r and your battery is unable to smooth out the ups and downs of the r/r output.
I use a plug in voltmeter in an accessory outlet. Google "Innova Equus"- about 13 bucks easily readable day or night. I don't know if it could be made waterproof. I just use it occasionally to ensure charging output is good at different rpms . It's a little distracting to watch as voltage tends to fluctuate as you change speed riding. Sounds like your battery light is doing the same.

[bwringer]

"Battery light?"

If you have a bike with that annoying outdated water sensor light (please tell us which bike you have, BTW) it's easy to shut off -- search the forum for details, since I don't remember exactly how offhand.

Now then -- grab a volt meter and hie thee hence to The Stator Papers.

It sounds like your charging system is either working OK or your regulator is bunk. And perhaps you have a combination of issues. The Stator Papers and a $3 hand held volt meter will reveal all.