1999 Grand Am Power Issue

[tubeman]

Problem started about 3 weeks ago. One day went to start the car and it was cranking as if the battery was dead. It started and drove fine until I stopped and wouldn't start. I assumed it was the battery and got it replaced the next day.
Last week, I started getting quirky things happening again, like the warning lights flashing after turning off the car, speakers popping, radio resetting, and only happening intermittently. Last night, went to start the car, loud popping noise from speakers and the car was completely dead - no power at all. Hooked up battery cable from a jump start for 30 secs - started immediately, turned it off after 10 secs and again started fine. No problems after that.
I doubt that it is the battery as it is new, and if it was the alternator, I don't think the battery would charge after 40 seconds.
Any ideas?
Greatly appreciate any help before I'm forced to take it in to the dealer.

tubeman.

[GTP Dad]

Check your ground wires. It appears that you have an intermittant ground that is causing a loss in voltage. It could be the main ground coming from the battery, the wire could have gone bad. Also check the bolt where the ground attaches to the block. If it is rusted or corroded it can cause a similar problem.

[tubeman]

Will check it tonight and let you know.

thanks for the quick response.