Last few weeks the battery seems really really weak after the vehicle sits for hours or over night, its getting worse, now in the morning it barley cranks. The battery was replaced 3 months ago, and last week I changed the alternator thinking it was the problem. I tryed a parasitic draw test. Put lead on pos term and other lead on pos wire unhooked from batt. It showed like .001 amps. I put wires on batt for voltage, it ws 12.5, Started van, it struggled to start and dropped to like 7 volts but once started up to 14.9 and 15 volts. Once the engine shut off, immediatly down to 12.7 and then just kept dropping .01 volts per second, downt o like 12.2. I opened the drivers door, it starte dropping .01 volts per second down to 11.3, at that point I closed the door and it rose .01 volts per second to 12.5. What could the problem be, did I get a bad battery?

 

Try removing a Positive lead after the engine start up. If the engine still running after the positive lead removed that indicate the alternator does keep the charge. If that's the case, you might have two or more bad cell battery.

 

Hey ...did you ever figure this problem out? I'm having a similar issue with my 2000 Silhouette: known good battery, but it will die overnight. Through some trial and error (and a lot of charging and boosting!!!) ...I think I have narrowed the problem down to the theft-deterrant system: if I don't "arm" the system, the battery will not run down. So ...my question now is, how do I disconnect, or disable the theft deterrant system? I know its a two-edged sword, kind of: do I want to risk having my van stolen by leaving it unlocked all the time, and with a "live" battery ..or do I want to have a securey locked and alarmed van with a dead battery

Any advice on how to disable the ant-theft system??