Black95MustangGT

Car wont hold a charge from time to time. It will just die when the car is sittin still.

The voltage meter will sometimes go all the way down to 8 and then up to 18.

When i turn on anything like my headlights or stereo it will dim really bad and start to stall.

Is it my alternator?

r.barn

could be either.

sounds like bad alternator, but if you're battery is dead it
will be putting more load on system than alternator can keep up with.

go up to Autozone, they will test both for free.

might be a bad ground issue too.
check all your grounds.

FivePointOhh

its your alt. i just had a similar problem. it takes like 10 minutes to replace it and it only cost like....70 bucks i think with a 20 dollar core from autzone. the car will still act funny for about 20 minutes after you replace it but then everything will resume as normal.

Black95MustangGT

when you say check my grounds, what do you mean?

and what is a core?

94StinkinLincoln

ok check both connections on your battery terminal. see if they are loose and/or have any corrosion. put a voltmeter on the battery with the car off. see what it reads. if it is below 10volts it may not crank. 9.6 volts is suppost to be the limit but some times it takes more. the battery can be old or discharged too much and will cause the plates inside to go bad and u get a bad battery. crank the car and check the battery with a voltmeter. it should read 14 to 14.6volts. it it reads lower than that or it reads the same as the battery when the car is off then it is more than likely the alternator. just make sure that ur belt is tight and its not dryrot. it will cause the alternator to not work correctly also. there should not be a drop less than .5volts from your battery to your alternator if there is then you have excessive resistance and will not allow the battery to charge correctly. sorry for the long post but it should help. autozone will check the stuff for you. but please take my advice and do not buy parts from them!!!!!! get them from carquest/napa or o'rylies.

94StinkinLincoln

your ground is the opposite from the power side. make sure from the ground side of the battery there is a wire to your chassis and the connection is tight. the core is a charge that you are charged when you buy a new starter, alternator, transmission, and parts that can be shipped off and refurbed. you can pay the fee or give them your old one as the core.