Volvo Station Wagon Battery Drain

I have a Volvo 940 station wagon that has worked fine but now if the car sits for a few days without being used it will go dead (needs jump start). I have replaced the battery and checked the alternator but both are fine. Anyone have any ideas on what it could be?

Someone needs to test the electrical system for a short circuit, which would cause a constant battery drain. It doesn’t take much to drain a battery. The alternator and battery can be perfect, and still, a short or some unknown battery drain will kill your battery.

Are you sure no lights are on when they shouldn’t be, such as the interior light, trunk light, or glove compartment light?

This is usually a not too hard job. First you need someone with a meter to measure the current drawn from the battery. Then after you make sure you have any codes necessary to re-activate the radio after it may have been disconnected, you start pulling fuses while your friend watches his meter. When record what circuit(s) are drawing power and how much power they are drawing. The circuit with the largest draw is likely the problem. Remember to turn off the dome lights. A wiring diagram can indicate what items are on the circuit(s) that has the large draw.

They should also check the voltage at the battery. It should be about 12.5V with the engine off and about 13.5 with the engine on.