Not charging with headlight on GS550 1979

[bill_face]

Hello.

i've been having some problems with my bike not starting after having ridden it with the headlights on.

I have cleaned up the connections around the charging system, fitted a Polaris R/R, eliminated the headlight loop & just bought a new battery. I did a Quick Charging Test on first run with the new battery & I've included the numbers in brackets for the old battery (which wasn't charged, just from running and riding the bike without headlight). I do have some LED daylight running lights that seem to drop the voltage around 0.5V

1) Key Off - expect 12.7-12.9V : Got 12.86V (12.12V)
2) Key On- expect 12.2-12.5V : Got 12.2V (11.48V)
3) at 1500rpm- expect 12.6-13.2V : Got 12.6V (11.96V)
4) at 2500rpm- expect 13.5-14V : Got 13.95V (12.95V)
5) at 5000rpm- expect 14-15V : Got 14.00V (13.5V)

So the numbers check out OK with the new battery.

However when I turn the headlights on at idle the voltage drops from 12.6 to 12.2 & then as you rev up to 5000V it doesn't rise above 12.6V.

Any ideas what would cause this?

 

[Gorminrider]

Idea #1=weak stator...one idea particularly from your description-you might have the "loop" figured wrong and be "missing" a leg of the stator. that is, it is running at 2/3rds output.
or the ground is poor at the r/r...connections ..look for heat etc etc...
AND always try an ac voltage check of the stator itself at 5k rpm...they need to test the same at all legs ...above 65vac to 80vac is normal (but lower readings will also work as long as they are the same on all albeit they won't suit the "tests" you are following