Battery Drain in a 2002 Camaro SS
 

I wanted to post this and get some feedback from you guys. Is there an easy way to check if a battery is being drained even with nothing in the car on? I bought a new battery (AC Delco) from my local dealership in June, 2020. Last Dec., 2020, I asked them to check the battery as my car wouldn't start right away and gave all indications of a weak battery. They said I didn't drive the car enough to keep the battery charged. I have previously let the car sit for up to 2 weeks between drives with no problems.
I checked the battery with a tester and it showed low, 5 volts, after sitting for a week. It finally started the car after 3 tries. The alternator checks out fine. After driving for 20-30 minutes and shutting the engine off the battery shows 12.5 volts. If I let the car sit for 2-3 days and try to start it I get the same slow response time.
I'm guessing either something is now draining the battery that didn't before while the car is sitting in the garage or this new (from June, 2020) battery is a dud and can't hold a charge. What do you guys think?

Maybe disconnect the battery while it sits a few days. I've had new batteries actually short out causing a drain. This would verify if the car is the problem or just a bad battery.

Here is the first place to start:

Disconnect the positive cable and connect a standard 12volt test light in between the cable
bolt / end and the battery lug. If it lights up with everything off, there is a draw in the system. the brighter the bulb on the test light the higher the amp draw is. If the test light does light up, pull fuses one at a time to find which circuit the draw is in. If the light still lights up with all fuse pulled, disconnect the wiring to the alternator and then the starter. See how that works before you blame the battery. What brand / manufacture battery is it? I have changed brands of batteries in my shop 3 times in the last 5 years. Currently I am selling Napa Batteries manufactured by East Penn Manufacturing little to no problems. I threw both AC Delco and Interstate out. Let us know how you make out, good luck.

Bill

This will work but you may have to connect a jumper wire across the test light connection for about 5 minutes first. Then disconnect it.. That will supply enough power to shut down any or all the electronics in the car.

I forgot to mention pulling any relays as well especially for time delay interior or head light circuits.

Bill

Thanks guys for your responses. The battery is an AC Delco brand. I drove the car today after having a hard time again starting it, then disconnected the battery and checked it with a battery tester, 12.0 volts. I'll let it sit with the battery disconnected and then use the tester again in a couple days. Sometimes I don't think of the simplest things first.

My bet the battery is junk.

Well after getting around 2 feet of snow and losing electricity, cable (TV and internet), and landline phone line (yeah I refuse to give up my old phone) I finally had a chance to full around with the '02 Camaro in the cold garage.
With the battery negative cable disconnected the battery held a charge for 4-5 days. After connecting it again the battery went down to 5 volts in a couple days. The 12V light tester lit up quite a bit when using it to test for battery drain.
I am assuming this means something is draining the battery when the car is off?
Now to the hardest part, trying to find where the drain is.

Thanks again guys for your input and help.

The test light method is ok for non- computerized older vehicles, but late model stuff needs to be measured in milliamps using a digital meter capable of such measuring. I reccomend taking it to a shop that you trust to check the car.

Disconnecting the power source, be it a fuse, a relay, or power source one at a time with the test light connected between the battery and negative cable will tell you which circuit is causing the drain when the light goes out, computerized vehicle or not.

Bill