Problem with battery and engine

[YodaSoldia]

came out yesterday and my battery was dead. bought a new one and replaced it, but didn't drive it at all. Came out 10 min ago to go do some stuff, and car doesn't turn over, nothing, not even the lights turn on.

also, i've been having a problem lately where my RPMs jump from idle at about 500, then climb to 1500. my check engine light turn on, and soon after my car smells like rotten eggs. what is going on?

[CAMAROWIDBASS]

rotten eggs smell is definately your cat, your cat is going out.

As far as the battery problem you could have a short somewhere but i doubt a short could kill you battery in less than 10 min.

[YodaSoldia]

the thing about my cat is the same day my battery died my car passed a smog test...

[98 3.8]

Have Autozone do a charging system check. It might be your alternator.

[YodaSoldia]

We did a diagnostic today to try and find out where the current was being drawn from. The car has a brand new battery, so there is no reason it shouldnt hold charge. The (-) negative terminal was removed, and a multimeter showed that there was a short somewhere as it registered almost 12 volts. When the multimeter was set to show mA, no draw was shown. As we were checking various things, the volts dropped from where they had started at almost 12 volts to nearly 11 in about 15min, so we know that there is a short somewhere. Any tips on finding this short? The multimeter is not showing any draw whatsoever, yet the battery is still draining. What gives?