Brand new battery car thinks it's dead

[Angela]

HELP!!!!! PLEASE

 

I have a 08 Grand Prix.  A few weeks ago it wouldn't start.  First my husband thought it was the anti theft system then 2 days later decided it was the battery so he put in a new battery and it has been working fine.  This morning I get back in it after picking up coffee.  Turn the key and the trunk pops open ---  Now the CAR WON"T START.   I mean nothing no click no dinging no nothing.  CAN anybody help PLEASE!!!!

[Frosty]

The most likely suspect would be your alternator is not recharging the battery properly when the car is running. It should produce ~14V to recharge your battery once your vehicle is running. Otherwise, you may have something like some sort of interior light, radio, etc. that is staying on after the car is shut off, draining the battery, or there is some sort of internal electrical short causing the battery to drain.

[JUSTA6]

Try recharging the battery.  If you have an Autozone, Orielly's ect nearby, they will test the alt for free.  The alternator would be my 1st guess as well.