I bought an 04 Mustang about 2 1/2 weeks ago and the battery light has been coming on every once in a while for the past few days. The voltage meter on the dash still reads right on top dead center so I'm wondering where the problem is. About a week ago I checked the charging system with the A/C on low (forgot to turn it off before hand) and I got a reading of 13.72. Do you guys think it's the battery, the voltage regulator or the alternator? If I have to swap out the alternator is there a higher output alternator available because I'd like to add fog lights and a few other doodads to the car in the future.

 

my 99 gt does the same thing. im not sure what it is but ive never had any problems out of it except for it blows my voltage regulator fuse constintly but still nothing you would ever notice cept for the light

 

It turns out it was the alternator. The battery was load tested by Autozone (505 CCA) and Walmart (590 CCA) so I tested the charging system again. With nothing on it was charging at 13.35 volts but when I turned on the AC, radio, lights and wipers it dropped to 13.05. That shouldn't happen so I swapped it with a rebiuld from O'Reilly's. What's great is the one that was in there was an O'Reilly's rebuild and it was gauranteed for life so they refunded my $270. I just had to pay a friend to install it because I didn't have the right tools.

 

i was told mine was my alternator too but its never giving ne any problems, i should probly get it tested though