Pontiac Repair: pontiac sunfire no start, pontiac sunfire, battery voltage

Question
my gf's car the Pontiac sunfire i believe a 1999 just recently stopped working like it cuts out some times you can drive it for a while then all of a sudden if you idle for a bit then put it in gear it stalls out and is totally dead it used to start with a boost,but after she took it to the garage and had a brand new battery and then an alternator installed it got her home then when she went to start it the next day it was totally dead again and this time a boost wont help it just clicks she just spent over 400 dollars and is a little  p/o'd  any thing would be helpful thanks

Answer
Hi Brad:

well it can be a few things. It can have some kind of a draw on the battery that it making the battery go dead like any kind of aftermarket stuff like a radio or amplifier or alarm system. It can have a bad connection somewhere at the battery or the ground wire on the body  and or engine. Lastly it can have a issue with the ignition switch where the contact in the switch are bad and when the car is turned on or cranked the battery voltage is low due to the bad contacts in the switch and that's why it will not crank or it was dieing at times. Just a hunch. Hoppe that helps you out a bit? Good luck :)