Sorry for the long post.
I posted a question in troubleshooting a few days ago and am afraid it didnt make much sense.
In my 69 SB, I have changed to a 100 amp 1 wire alt. to cure my dim headlight problems. During the day with no lights on my voltmeter reads 14v. at cruise, 13v. at idle Even with my stereo cranked (roughly 800 watts worth of amps) the volt meter reads 13.5v. cruise, 13v. at idle.
When I turn on my parking lights only, it drops to 12.5v at cruise, 12v. at idle. With headlights and parking lights its 12v. cruise, and 11.5 at idle. With the stereo on the bass cuts out at mid volume volt meter drops to 11 at cruise headlights dim, etc. When I turn on my signals the voltmeter jumps a half a volt each time it blinks. Is that a clue?
Now I figure (with ohms law) that my headlights and parking lights etc. are drawing no more than 15 to 20 amps. Now I know my stereo draws way more than that!
So my question is...Is there something simple I am overlooking? Everything is fairly new and in good condition. I am not as entirely as familiar with 12v. systems as I am 120v. and 240v. systems. Am I somehow losing voltage somewhere. Can bad grounds cause this?
Any suggestions will be put to good use. I just need a push in the right direction.
BTW. I had Sylvania X-tra brights for headlights, and switched back to normal hologen to see if that made a difference, only difference it made was to make the hologens obsolete, but no change in voltage drop. Thanx, Sean.