2006 GS500F not charging battery

[gsJack]

My GS battery voltage at idle has always checked out to be same as battery is before it's installed.  It's always been over 13.5 volts @ 2500 rpm and under 15.5 volts @ 5000 rpm as specified in the John Bates write up.  I have over 170k GS500 miles in without any regulator or alternator problems, 80k miles on my 97 GS and 91k and counting on my current 02 GS.  Lots of new batteries over the years.

http://www.bbburma.net/Documents/JohnBates_ChargingCircuitTests3.pdf

[Nick89]

At idle I'm getting 11.8 volts, at 3000 RPM I'm getting 12.4, and at 5000 I'm getting 13.4.

Whats your guys opinions? shout I get a new regulator?

I checked my Yamaha FZ6R just for some kind of reference and the battery at idle is getting 13.5 volts.