After a recent long drive (~2 hours), I found that my (more that three year-old) battery was smoking and smelled of sulfur. I understand this indicates a severe overcharge, but fortunately it didn't explode. Now, a couple days later, the 99 Maxima won't start. Lights on the interior turn on, but are very weak, and the engine only clicks and doesn't try to turn over. Battery is toast, obviously, but here's my question:

Might this be caused by a bad voltage regulator/alternator? If so, am I in danger of ruining the replacement battery driving the < 5 miles to get the alternator checked?

Thanks!

 

The battery must have already been bad. If it was over charging that much you're lucky you fry everything electrical in your car.

 

Get a volt meter.

 

Did you check the water level in the battery? And how old is the battery? When batteries get to be 5 years old, they are are at the end of their life. Some of the top of the line batteries will last a couple of years longer. You may just have a bad battery, the alternator may be just fine. But check the alternator anyway, just in case.

 

Thank you for the replies. The battery was indeed 4+ years old, and now that I've replaced it the car starts without issue. I'll get the alternator checked out before I do too much driving with it, of course.

There wasn't any need to check levels on the old battery, as it was sufficiently decimated.

 

Whelp, just tested the alternator: Pushing 17 (!) volts. So there's that.

Any idea idea how much it will run me to get replaced? I don't have the means to change it out myself, unfortunately.

 

It depends on the shop you use. If they use a rebuilt alternator, you wuold be looking at around $350.

 

Most likely all that's wrong with it is the voltage regulator went bad. It would probably cheaper just to have it replaced rather than purchase a whole new unit.