Stator Papers 3

The Quick Test

By Posplayer (Jim Moore)

This test was developed by Posplayer as a way to simply check your GS Charging system without the need of tearing into the bike. This is helpful in providing an initial view of the charging system before going on to the Stator Papers 4 - The Fault Finding Chart.

NOTE: This is not to replace the Stator Papers 4 - The Fault Finding Chart. It is just a quick sanity check to see if the battery is good enough to proceed with the Fault Finding Chart. The first part of the stator pages will actually measure how good your connections are and goes well beyond this QUICK check.

The Quick Test involves taking 6 readings at the battery. While this is pretty simple to do, decyphering what the various numbers may be complex to some. If that is the case there are people who hang out in The GSResources Electrical forum who are willing to help you to figure it out. If you need help, then go here to post your results and questions.

Quick Test Steps

  1. Key Off = Normal 12.7v-12.9v
  2. Key On (but not cranking with lights for 10 sec) = Normal 12.2v-12.5v
  3. At Idle (1500 RPM) = 12.6-13.2v
  4. At 2500 RPM = 13.5-14.0v
  5. At 5000 RPM = 14.0-15.0v
  6. Key Off = Slightly higher than measurements at #1, 12.8v-13.0v

Quick Test Diagnosis Summary

  1. Basically Step #1 and #2 is making sure the battery is charged and in good health. The drop should be about 0.5 volts for normal headlamp and coil load (without cranking the starter). Any more than 0.5v drop indicates the battery is weak even though the static voltage is OK (12.7-12.8v).
  2. Step #3 - This is to get a baseline starting voltage. This will vary some depending upon your idle and the particular R/R you have. It could be lower than the off voltage or as you idle up it will increase to 13.0v.
  3. Step #4 - By the time you get to 2500 RPM you should have close to the maximum output voltage even if you have bad connections. You are not pushing as much current and this shows that the stator is likely good.
  4. Step #5 - By the voltage at 5000 RPM being higher than at 2500 RPM you have a pretty good indication that your connections are good. If the voltage at 5000 drops from 2500 you have bad connections. If you already checked the grounds then it is likely in the positive legs between R/R(+) and Battery (+). Check fuse box and the large bullet connector to the battery. If the voltage climbs above 15.0v it is likely the R/R not regulating and is bad bad.
  5. Step #6 - If after running for a few seconds in a charging state, the voltage to the battery should have risen a bit. If it is lower than where you started then you did not charge at all. Again, this will vary somewhat depending upon how long you let the bike run.


Next article: Stator Papers 4 - The Fault Finding Chart