Battery starts to die with defroster on

pompeii

New Member
Feb 8, 2013
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Last week on an especially snowy day I kept putting on the defroster while blasting the heater early in the morning. After getting about 10 minutes from my home, at a stop light, I noticed the lights on my dash flickering and the battery gauge was wavering. I flipped off my lights, heat, defroster and the gauge went back to normal. At this time I noticed a faint burning plastic smell and was worried I was going to have to pull over and call AAA. But the car made it home and I put the battery on a charger. It showed the battery wasn't fully charged, so I charged it.

Now, it happened again. I'm hoping its just the battery that needs to be replaced. But is a battery kind of half dying like this indicative of a bad battery? I would have expected it to just not start in the morning rather than die from draining too much power. Also I read somewhere that the burning plastic smell is something that can happen when an alternator is on the way out, though earlier today when the battery gauge started to drop I didn't smell anything.
 
if your car is at least 9-10 yrs old and has over 100k miles on it, i have looked at many v6 edge mustangs and many had new alternators.. i just bought a 2002 with 127k on it and the 1st thing i did was replace the alternator.. i drive out of town alot and didn't want to end up on the side of the road...you can check the alternator with a voltage meter to see if it's putting out the right voltage.. if not, it'll kill you battery in no time... advanced or autozone can check it for you... new one cost $200 from them... i opted for a reman unit off ebay for about $90...ALSO... your battery gauge one the dash should be registering over 13 volts, or something's not right... good luck...