No start, flat battery

[DonDDR]

Bought the car on saturday, nice clean 94 auto. Guy I got it from put a new battery in it. I thought it was because the car had sat for 4 months. Drive it around sat and sun, 30 or so miles, and go to the store for dinner stuff and it wont start. Jump it and it comes alive right away. Drive it around again and same situation. Go to Autozone and have dude check the alt output, its 14.5 at idle. Sufficient or better. He tells me it might be the ground straps from the engine/trans to the chassis. He clicked that right off like he used to be a Ford tech at one time and kept saying "these cars" like he was real in what he knew, anyway, went to Interstate batteries and had them check the 2 week old Megatron. Load test and hydrometer test the cells and it its perfect. Is autozone dude full of it with the ground straps? Or for real? Or how do I diagnose a drain problem on a car like this? I have (and had) my share of Fox Mustangs, and can get thru a problem like this. But the SHO, so many electronic circuits, where would I start?

TIA

 

[Sarge1400]

I'm pretty new here too, but I remember reading about three critical grounds. I can't recall all of them right now, but I'm sure someone will be along shortly to let you know.

 

[Bob Gervais]

As the AZ guy mentioned, check your ground cable, from the battery to one of the studs that fastens the starter.

Also check your cables and terminals for looseness, corrosion, etc.

If it has el-cheapo clamp style cable ends on the battery, change them to something better.

 

[NEp8ntballer]

the starter circuit isn't too complex, I'd start there. you could also just borrow a ground from a car the next time it won't start and see if that does the trick