Hyundai Repair: Hyundai Accent Battery Drain, negative battery cable, engine immobiliser

Question
We have a 2000 Hyundai Accent with 35k on the clock.  We keep having problems with battery going flat - it jumo starts fine but if not driven for 2-3 days it goes flat.  I have been told by someone else that they had a similar problem with a Hyundai Accent (not sure of year model) and they thought it was due to the engine immobiliser and they turned the car over every day to make sure it did not go flat.  Any suggestions?  Thank you.

Answer
First, check the battery, preferably with an electronic tester.  You've listed the symptoms of a dying battery.  Your local parts places may be willing and able to check your battery for you if you take it in.  I've seen the ones here check the batteries prior to selling them.

Second, check for draws.  With everything in the car off and key out of the ignition, remove the negative battery cable and insert an ammeter between the cable end and the negative terminal on the battery.  You should read less than about 50mA.  If it's significantly more than that, you'll need to locate the source of the electrical draw.