badstang123 10+ year member
Senior VIP Member
I recently put a digital voltage meter in my car so I could keep close tabs on exactly what my voltage was doing. Just to give you a background I have a 200 amp alternator 200 amp alternator, all zero gauge wiring, and two optima red top batteries.
Now here's the weird part. My stereo can draw about 150 amps at full output. To test for any discharge at high output I revved the car up, cranked the stereo, and ran the A/C to see what would happen to the voltage. It stayed right on 14.4 even with all that draw. I was impressed that the alternator was keeping up no problem. Then I realized at night with both A/C and stereo off, when I turned the headlights on the voltage would drop to 13.7 and wouldn't go any higher. I started messing with things and no matter how much crap I had running the voltage would always stay at 14.4 volts. Also if I had nothing running it would stay at 14.4 volts. Then if I turned the headlights on it would always drop to 13.7 volts. Also if I run everything and the headlights it still stays at the 13.7 volts. I wouldn't think 55 watt bulbs draw anymore than 20 amps. That makes me think there has to be something funny going on with something in the headlight wiring. I'm hoping one of you guys has an idea as to what would cause this. I would appreciate any help.
Now here's the weird part. My stereo can draw about 150 amps at full output. To test for any discharge at high output I revved the car up, cranked the stereo, and ran the A/C to see what would happen to the voltage. It stayed right on 14.4 even with all that draw. I was impressed that the alternator was keeping up no problem. Then I realized at night with both A/C and stereo off, when I turned the headlights on the voltage would drop to 13.7 and wouldn't go any higher. I started messing with things and no matter how much crap I had running the voltage would always stay at 14.4 volts. Also if I had nothing running it would stay at 14.4 volts. Then if I turned the headlights on it would always drop to 13.7 volts. Also if I run everything and the headlights it still stays at the 13.7 volts. I wouldn't think 55 watt bulbs draw anymore than 20 amps. That makes me think there has to be something funny going on with something in the headlight wiring. I'm hoping one of you guys has an idea as to what would cause this. I would appreciate any help.