Draining overnight or while you're driving? Do you have a digital voltmeter? If so, measure the battery voltage while the engine is running.
Apr 25, 2011 at 6:13 PM
CARADIODOC
✓Experienced Mechanic
34,398 POSTS
Oops. Forgot to mention that it should be between 13.75 and 14.75 volts. If it's lower, suspect the generator but we'll need to take some voltage readings first.