This is the second battery I've been through in 9 months! Alternator checks out fine and just had starter replaced. Any input would be much appreciated

 

do you have a stereo in the car?

 

Most batteries come with a warranty. I would go back to where every you purchased the battery ans have it checked. It would be defective and I suspect they will give you a new one under warranty.

 

I would do a parasitic leak down test to find out what is discharging/shorting the battery. There should be no reason why you are going through so many batterys.
But with that being said what are you using for batteries?

 

Do you have any aftermarket electronic devices (H/U, LCD screen, etc.)installed in the car?

It’s not unusual for an installer to connect a device to a constant power source, resulting in a miniscule drain that eventually kills you car’s battery. If you do have any aftermarket electronics, check that they are connected to an IGN switched power source.

 

I don't have any stereo equipment or navigation, etc. I have had the cat for 7 years it only had 28000 miles on it when I bought it. However I found out after the fact that the previous owner had a Supercharger and NOS in the car so over the years I have noticed a lot of the wiring has been displaced. Thanks guys for all of your input so far! The throttle body was also replaced before the starter was replaced. I think it might be my REV lamp relay under the hood because I used a test light on all my fuses, relays and I got nothing when I applied it to the rev lamp relay?

 

The battery is ACDelco Professional 640 CCA 100 RC

 

For sure... You have a parasitic leak that drains the battery.

 

What is a parasitic leak if you don't mind me asking?

 

remember google is always your friend.

https://www.google.com/url?sa=t&rct=...vkgEP3pN9N3A-Q

 

Thank you my friend! I got so caught up in the forum I didn't even think about google.

 

I wish you luck electical issues like that can be a pain to find.