Expert: Josh Fields - 12/6/2006

Question
Hello, just found this site and your knowledge seems promising as I do need some help.
Ok now the problem,
I was driving down the street and my tach and mpg estimate gauge started acting erratically (jumping up and down) lights went dim and car semi jumped a couple of skips and then died.
I had the battery checked where I bought it and they said it was good. I put in a rebuilt alternater about 8 months ago.
Now I compress started it in reverse and let the car run for a few minutes and then removed the positve cable from the battery and the car immediately quit. I was also told that the car should start by battery power only but car still will not start....not even a click. Lights come on but dimly.
I have a few ideas as to what the problem may be but could use some expert advise.
I truly do appreciate any help!
Thank you,

Chris  

Answer
Chris,
 If your lights are dim and the engine is not running then it is 100% because of a low/dead battery.  Also if the car is running and you disconnect the battery it doesn't mean much, because the battery is in the loop with the alternator.  Even if the battery is bad, the alternator can still keep your engine running... but it has to run through the battery to do so.  So if you disconnect the battery cable, not only have you disconnected the battery, but also the alternator which uses the battery as a path.  Its either the battery or the alternator.  I know the alternator is relatively new, but its not out of the question for it to be bad.
 Most parts stores will do a free alternator scan.

 Good luck,
 Josh