Ok so here's my story. About a week and a half ago, my car starts acting up. The lights started to flicker and the CD player cut in and out. Well we replaced my battery b/c its been about 5 years and it was about time, and she ran fine after that for about a week or so. Well last night I was driving it to go get some dinner and my car starts actung up again. I have a pretty large sound system in my car, a 1600 watt amp, and two 700 watt rms 12" subs. Well the lights would flicker and dim when the subs hit, and then the CD player would cut out. And whenI went from high beams to low beams the CD player cut out. Is this due to a dying alternator? Or is there something else causing this? I check all my wires this week and the connections were all good, so I doubt its that. Thanks for all your input!

I also had the alternator tested, it pushes normal amos like 70 or 78 or whatever when the amp is off, but like 48 when the lights and amp are on. is this normal?

 

Ok more news. I went out today to the movies, and my car started right up and ran with no problems. But after the movie, I coudln't start it, I got no power anywhere. I got a jump and it ran fine except when I turn the lights on. When I turn my lights on the CD player cuts out. And now that I'm inside and the car is outside its dead. I don't know whats going on. Anyhelp is greatly appreciated.

 

How does your car run with the stereo off, and if you disconnect the system all together. Sounds like you have insufficient current for the load.

 

more like insufficient output from the alternator. could also be a really bad ground...

what you're experiencing is when you place any type of load on the alternator, its having trouble coping. you could be looking @ a number of things. of course... your alternator could be failing. however... it could also be the rectifier. if you have a multimeter.. .or no someone who has one... i'd suggest using it to check resistance in both the B+ side of the charging system as well as the ground side.

B+ Side... set the multimeter to the ohm setting (omega symbol). but the positive lead on the B+ POST on the alternator. this is usually the largest cable, which you can trace back to the battery (POS) terminal. place you negative lead on the battery post. do not use the cable itself or the terminals for readings... since you're bypassing a point of possible resistance. report back w/ your findings... high numbers (above .3 ohms) indicate high resistance...

anything beyond that will cause you to have issues getting the rectifier to adjust the voltage input for the alternator to handle the load

Ground Side... again, w/ the multimeter on the ohm setting, place your positive lead on the negative POST of the battery. then, place your negative lead on the alternator's housing. this will tell you if there is high resistance in the ground side. look for readings above (i believe) above .1 ohms to inticate a ground problem.

these are simple tests. to determine a possibly simple problem to fix. high resistance could be loose connections, corroded connections, broken cables, or even just a corroded battery terminal. these are all far easier to fix than replacing an alternator (cheaper too)

hope this helps... i'll check my numbers in the morning to make sure i gave you the correct resistance specs... good luck

 

Well I don't think its bad groundings or anything, I just replaced the battery two weeks ago. I'll try the ohm tests out sometime this week when I get a chance.

However, I have new problems. The car won't start. If I turn the key I get nothing, no power, nothing at all. But if I jump the car or get it rolling and pop the clutch I can start the car. My parents have already paid for a new alternator, so I figure I will go ahead and put it in and then run the tests.

Musicman - the car acts the same when the amp is disconnected as well.

 

yup, thats the alternator.

 

yup that was it. a new alternator and we're good to go.