Parasitic Load
FLL When you get your walmart Multi-meter, make sure you get one that has a DC current measurement capability of at least 10 amps. With a fully charged battery, disconnect the positive cable and place the meter between the + battery terminal (red test lead from meter) and the + battery cable (black test lead from meter) that you just disconnected. Prior to connecting the meter, make sure the Red test lead is in the "10A" position and set the meter dial to the DCA (DC amp) setting on a 10 amp scale. Close all the doors, turn off all the accessories and see what the meter reads.
A typical modern auto will have a "parasitic load" of between 50 and 100 Milliamps. Any current draw significantly larger than that means something in the car is drawing current from the battery when the car is shut down. You can probably identify the offending circuit by pulling fuses one by one until you see the excessive current draw eliminated.
Chaffed wiring., defective switches, defective electronic components and commonly bad diodes in the charging system alternator are all probable causes of these parasitic loads.
IF during the initial testing you measure a parasitic load within the typical 50-100 ma range, your car is acting normally. It's not uncommon for car batteries to go dead after several weeks of non use due to the small but constant current draw from the ECM and radio.
Good Luck
Charlie T
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