1997 Buick LeSabre battery issue

HELP! We have had this car to every mechanic in town and everyone thinks they have found the problem and fixed it, they have not. My daughter’s car won’t stay running. There appears to be a drain on the battery, which we have replaced 3 times. The first guy said the battery won’t hold a charge, get a new battery. The second said there was a bad connection to the trunk light, he snipped it. The third said her tape player was continually ejecting, he took out the radio/tape deck. Now we replaced the alternator. It still does the same thing. When the battery is brand new it will run without problem for about 1 week. After it has been jumped it will only last a day. Now that it has been jumped a few times it will only last hours. Actually that isn’t entirely true. If you let it sit after being worked on it will start up with out problem. It is after you drive it around a few blocks and shut it off that the battery dies. We are completely stumped and don’t know what else to do. What are we missing?

This car has two positive battery cables. Corrosion where the cables overlap can cause a lot of battery related problems. You can stare at the cable until the cows come home and it looks fine. It’s not until you disassemble the two cables that you realize there is a problem.

In addition to what @rattlegas mentioned . . .

I suspect nobody has performed a PROPER parasitic draw test

It should be fairly simple for an auto-electric shop to determine what’s causing the problem. Fixing it may not be so simple. But figuring out the reason for the battery drain, while potentially time consuming and therefore expensive, shouldn’t be that difficult.

If I had this problem on my Corolla here’s what I’d do first:

  • Inspect and clean the main battery connections.
  • Inspect the battery cables per @rattlgas 's suggestion. Both power and ground side.
  • Charge up the battery with a battery charger for 48 hours.
  • Battery load test.
  • @db4690 's suggestion of a parasitic draw test.

Knowing the exact details of the no-start symptoms would help in formulating a guess but have they considered the possibility of a problem with the junction terminal connection?

All electrical power except for the starter motor windings go through that terminal and an iffy connection can cause all kinds of problems from randomly dying to random no-starts which may mimic a bad battery. The terminal is located near the battery and is very easy to clean.

It’s corrosion or scale and due to heat through the connection that causes the problems.

Also, a voltage drop test between the alternator and battery can help identify other charging system problems. I had a similar problem with my '88 Toyota. I wound up replacing a fusible link and running a new wire to fix the problem.