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OK, I've been searching on here for a while and can't quite find the answer im looking for.

Today on the way to work, I noticed the battery light faintly flashing about 5 min into my commute and it progressively got worse, with the CEL finally coming on about 45 min into my drive. I noticed that it ONLY flashes while im in drive, and about 30 seconds after I park. On the way home from work, the flashing was more intense, and the light stayed on for longer periods of time. I also noticed that as the light is flashing while im parked, my rpms jump up and down from around 1.5k to 2.5k. When the light finally goes away, the idle returns to its normal 900 or so.

I took my car in to have the battery/alternator tested and battery tested bad, and alt tested around 13.5V - 13.8V.

I've read people changing the alts only to have the same problem arise a couple weeks later. Could this be a voltage regulator? Or a distributer problem? There is an oil leak inside my distributer and idk if that have anything to do with that.

 
Rep Power: 173

How old is that battery? Since the electrical system runs everything through it, a bad battery can be the culprit for a lot of vehicular hijinks.

 
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*UPDATE
The battery was in fact bad, as well at the alternator. I did voltage checks while the engine was running and it didn't put out more than 12.5V. I replaced the battery and picked up an Ultima alternator from Oreillys. It was quite a bitch to get the old one out but I managed to push it over and up in between the engine and firewall through some hoses.

I also replaced all positive and negative leads from the battery with some 4GA wire after finding corrosion on the ground wire where it terminates into the frame.

As of now I haven't had any trouble and no more battery light, but time will only tell with that reman alternator.