This test will tell you if any power is being pulled from the battery. Batteries only store electricity and not make it, It stores what your alternator gives it. How much your alternator gives it is determined by the voltage regulator.

How to test for a battery drain: Remove the negative terminal and connect a test light between the battery terminal and the cable end. On initial connection of the test light the bulb will light up real bright. " IMPORTANT " You must now reconnect the battery terminal by just touching the cable end to the terminal for 30 seconds. MAKE sure the test light is connected at this time. This function allows the delay dome light relay to charge up or other wise the test light will glow and give you a faulty reading. Now remove the cable off the terminal "With the test light connected" = The test light should have a very dim light now. If not something is drinking the electrons out of your battery!

We call it the consumer. To find the consumer you need to start disconnecting one fuse at a time. In some cases the fuses are under the rear seat. NOTE: The 89 900 has passive seat belts and they are known for this problem. In other cases it can be a bad brake light switch, causing the brake lights to stay on all the time. Other consumers are improperly wired phones, Stereo, amps, power antenna, and Little things like THE TRUNK LIGHT! Keep in mind to turn everything off when doing this test or the test light will burn bright. If you open a door you will have to reset the light as mentioned above.

When you find the consumer the test light should return to dim as soon as you shut it off or disconnect it.

The above test can also be performed with a volt meter. When all is good you should have a reading of around 4 - 4.5 volts DC. If you have 12 volts, again something is drinking from the electron well "battery"

Another simple test when your battery goes dead is to: Pay attention to the "ALT" or so called battery light. Turn on your key but don't start the Saab. Just put it in the mode where the dash lights light up. MAKE sure the "ALT" light is lit up. If not the alternator is not working in most cases because of bad brushes at the voltage regulator or the GROUND WIRE has separated. Make DAMN sure the ground wire is in top condition and it don't hurt to have two on there or a larger one than what came from the factory. The ground wire is black and connect directly to the alternator housing and to the engine block. If you listen closely you can hear the alternator whining. Turn on your headlights and make the alternator work harder. Note how the whining increases.

As a professional Saab Mechanic this is one of the sounds I pay attention to when doing service work. When all is fine on the Saab it has a certain purr with associated other noises. In the case of certain other frequencies and interruption of the purr tells me its time to inform the customer I smell fish. On the subject of smell it applies too!