Ron

Has anyone removed fuses with a meter hooked up to their battery to see if they could tell where the drain was coming from. My car has a 20 milliamp drain, not real high. When I checked it in January; that figure did not change whether the alarm was activated or not.

If my math is correct (which is saying a lot for me) I figured that a 18 milliamp drain on a 40 amp nominal capacity battery (10 hour rate-amp hour) would lose 1 amp/hour of capacity in 55.5 hours or 20 amp hours in 46 days, i.e., 6 weeks. So that would mean the battery would have lost 50% of its capacity.

My question is not intended to be an inquiry or discussion regarding what’s the best battery or the best charger or system for changing and/or keeping your battery charged.

Bruce SEA 993

Never measured the drain with a meter but the battery will drain enough to cause trouble if left for two weeks or longer. Plus it is not good to let the battery deep cycle. I just use the on board trick charger if I leave it.

Cheers

JasonAndreas

Yes, my problem was/is the CCU but even with the alarm turned off (it is always drawing current and monitoring doors, radio, etc.) there is going to be some draw (DME control unit is 1.4mA, window relay is 10mA, etc. etc.) The alarm unit is the only control unit in the car that you can interrogate with a Bosch Hammer with the ignition turned off.


There is a great 8 page Technical Service Bulletin for diagnosing a discharged battery. It goes through troubleshooting the alternator, voltage regulator, relays, ignition components. The TSB is part identifier 2706 and number 9402.

Ron

I have the written workshop manual but I don't think I have the TSB's.

I do have AlldataDIY for 3 other cars, not the Porsche, and I contacted them to see if they had the two you indicated. They said they had 2706 which is "2706 DEC 97 Battery - Revised With 70 Ah Rating"

They did not have anything with a 9402 on it. Are you sure that is the right number for another TSB?

JasonAndreas

2706/9402 are the numbers in Service Information Book K (white book) from Porsche for a single TSB. The name of the TSB is "Diagnosing Discharged Battery". Another example would be, Part Identifier 4490 / Number 9406 -- "Wheel Alignment Specifications for the Rear Axle" (which describes changes made to the spirit level that is used to measure kinematic toe). I'm sorry I don't have them in a digital format or I would just send it to you.