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On 30 Nov 2005 at 20:07, Fiesta Cranberry wrote: > >That sounds pretty high for idle, or did you > >blip the throttle while you were > >measuring? > > I was giving it gas to rev it up. Okay, that makes sense. Try it again and slowly give it gas while watching the voltage. The number we're interested in is NOT the highest number you ever see, but rather the constant value it settles to as you go up in RPM. What you'll see is the voltage rise as the rpms go up from idle. Initially, the VR is just asking the generator for everything it's got. At some point the VR will start to work to limit the output voltage. At this transistion, there is always some overshoot as the VR takes over, so you need to ignore the overshoot and just look for the value that you see after you're past the transistion. If you made a graph of voltage vs. rpm it would be a ramp that started at the battery static voltage and ramped up with a little squiggle at the upper end of the ramp and a level "plateau" after that. It's the voltage on the level part that we're interested in. That "plateau" is the VR's regulating voltage and it should be 14.1-14.4V measured at the VR or battery. It will be about 1/2 V higher at the generator and a bit lower at the fuse box, where it just happens to be a lot easier to measure. If the voltage is too low, the battery won't get fully charged, and FI cars will start to run rich at some point. If the voltage is too high (this is uncommon) it's hard on your battery. I generally tell people to replace the VR if the regulating voltage has fallen below 13.5 V, because that's where FI problems seem to set in. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~