I think there are two things to check.
1. charge battery, disconnect from car, leave a "week" test with meter. If readings are poor then you can fairly well illuminate the car.
2. using amp ampmeter with the battery connected to the car put the ampmeter in line with the positive? and test for a discharge. If you get a reading above x then may be an idea to pull fuses to see whats drawing power.
Hopefully someone can tell you what x should be and if in line with positive or neutral.
macafee2
|