I recently bought a 1968 mustang. I wanted to upgrade the headlights since they were horable so I chose HID since they only consume 35 watts vs halogens at 55+. The problem is, my headlights won't turn on unless they get a consistent 12 volts. If I turn on my headlights when the engine isnt running and reved very high so the alternator is kicking lots of voltage back to the battery, they wont turn on. THen when I am sitting at idle for more than a minute or so, the volts will slowly go back down and the headlights will shut off (sometimes only one, but sometiems both). Then I have to turn the headlights off, rev way back up and then turn them back on. How can I ensure my electrical system stays at a consistent 12+ volts? Do I need a better alternator? Do I need a new battery? Do I need some compacitors or something?
Thanks!
2007-10-05 12:06:41 · 4 answers · asked by Matt 2 in Cars & Transportation ➔ Maintenance & Repairs
i think you have a faulty voltage regulator on your alternator .start up your motor with a volt meter on the output side of the alternator.it should put out 14.5volts approx.check it for voltage fluctuation.if it is erratic suspect it as faulty.hope this helps you.
2007-10-05 12:19:00 · answer #1 · answered by the rocket 4 · 0⤊ 0⤋
You need a better alternator. Even at idle, the alternator should easily be able to maintain 14 volts with the headlights on. Or, you have too large a pulley on the alternator, so it doesn't turn fast enough at idle. The battery should be able to keep the lights on for an hour or two with the engine off too, so the battery might not be in real good shape.
And, always look for lousy grounds. If they're bad you won't get 12 volts to the headlight even if the battery/alternator is putting out that much. Get a voltmeter and put it between the ground pin of the headlight and the negative battery terminal. You shouldn't have more than 1/2 volt.
2007-10-05 13:40:57 · answer #2 · answered by Nomadd 7 · 0⤊ 0⤋
Your battery should be at 12v all the time. Running the alternator should be putting out between 13 to 14 volts. The problem may just be the old wires. You may also try cleaning the battery and electrical terminals. Then put a volt meter on the battery and check it with the motor running and off. Good luck.
2007-10-05 12:21:10 · answer #3 · answered by mad_mav70 6 · 0⤊ 0⤋
You need a constant voltage regulator installed in the high light system at least.
This would either be in addition to the stock system, or instead of.
It would have a power transistor, some capacitors to maintain a close tolerance for the head lights.
If you have a newer sound system, it could benefit from this too.
2007-10-05 12:21:35 · answer #4 · answered by yosemitezuzan 2 · 1⤊ 0⤋