89 Geo Tracker electrical problem help!

Bought this Geo Tracker a few weeks ago. First it had a starting problem and had a new starter installed. Still did not start. Finally brought it to Oxnard Auto Electric and they said it was the voltage relay and it started. I put a brand new battery in it and this morning for the 2nd time the car just dies and the battery seems to be dead. What now?? You can tell because the lights dim, turn signal no longer functions and the engine just quits. A fresh battery gets her back running but something is pulling the juice from the battery. Any clues?

Two things I would check.

Number one: Is the altenator charging the battery while the engine is running, or is the engine just running off the battery voltage?

Number two: Use an amp-meter to measure if there is an amp draw when the car is off. There should be a very small amp draw to run the clock and for the ECM memory. If it is larger than an amp, track down the device that is robbing the juice from the battery.