How can i check if my alternator is working? I can boost my car, let it run for a while, but once I turn it off and start it again, it wont start? Is this the battery unable to hold a charge or the alternator? Thanks.

 

well, besides taking it to a auto parts store and have them test it you can, with the car on test volatge to the battery, it should be around 14 volts.

 

If you have access to a voltmeter, the test is simple. If not, some autoparts stores will test the charging system for you.

With a meter, with the engine running at around 2000 rpm, the voltage across the battery should measure in the 13.5 to 14 volt range.. Do this with everything but the engine turned off. That means heater fan, radio, lights, whatever. If it's much below 13.5, something is not right. Clean the battery terminals and check the ground connection.

 

I heard something about while the car is running, unplug either the negative or positive terminal on the battery and if the car dies, it is the alternator, if not, its the battery? Is there any truth in this?

 

Also, if the alternator wasnt working properly, and i put in a new battery, how long until the battery dies?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autobot_Killer &raquo;</TD></TR><TR><TD CLASS="quote">I heard something about while the car is running, unplug either the negative or positive terminal on the battery and if the car dies, it is the alternator, if not, its the battery? Is there any truth in this?</TD></TR></TABLE>
Yes

 

so which one do i unplug?

 

oh yeah, my baterry is about five years old, think that maybe the battery is just toast?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autobot_Killer &raquo;</TD></TR><TR><TD CLASS="quote">so which one do i unplug?</TD></TR></TABLE>
Negative

 

So let me get this straight, if I boost the car, let it run, unplug the negative side of the battery and if the car dies, its the alternator, if the alternator is fine, the car should still be running? What's the theory behind this? Thanks!!!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autobot_Killer &raquo;</TD></TR><TR><TD CLASS="quote">So let me get this straight, if I boost the car, let it run, unplug the negative side of the battery and if the car dies, its the alternator, if the alternator is fine, the car should still be running? What's the theory behind this? Thanks!!!!</TD></TR></TABLE>
No electricity = no run.

 

this wouldnt damage anything?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autobot_Killer &raquo;</TD></TR><TR><TD CLASS="quote">this wouldnt damage anything?</TD></TR></TABLE>
There's a chance your battery will blow up.