I've got an 86 IROC Z28 305. Took the kids to school and came home. When I got ready to leave 30 minutes later car was dead. I hooked up a charger to it and 45 minutes later it started. Drove into town but the gauge for the batt. never made it to the half way point, in fact the more I drove the needle kept going down, to the point that when I would put on the brakes the radio would go off.
Is the a bad battery or bad alternator?

 

Alternator probably.

 

Probably the alternator. Check the battery--a weak battery can overwork the alternator and break it.


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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

At this point it's probably both. Once you kill a battery driving with a dead alternator, the battery will prolly be bad enough to kill your next alternator too. Try charging it up to make sure, if you fan get a full charge on it then you are OK. Just a head s up thats all.