Long time lurker and more recent owner of a 97 C2. I absolutely love the car and I leave it on a tender when I am not driving it every day.

So, I moved the car twice yesterday just out of the garage and back into it with no issues. Today when I tried to fire it up I got a battery light and a click of the starter but no turning over.

My theory here is the fan for the climate control system but for now the car is back on the tender. Battery is a June of 16 Interstate battery so I want to think that isn't the issue. I've been storing the car in the garage without locking the doors and I've seen some historical posts that it could be that.

But I'd be happy to hear any other theories or things to check while it sits on a tender overnight so I can try again tomorrow.

 

I never lock the doors. If it's the fan in the CCS, you can hear it running. Your best bet is to use a digital multimeter and check the milliamp draw. Plenty of threads on how-to but, in essence, disconnect the neg battery connection and put the ammeter in line with the neg. post and the neg cable. Route the leads out and close the "frunk" lid. Let the car go to "sleep" for a few minutes, then check the draw. It should be no more than 35-50 milliamps. If it's larger than that, pull one fuse at a time and go through the same process until you find the culprit circuit. Then investigate every item on that circuit until you find the one that's creating the draw.

 

The car uses slightly more power if the alarm is not engaged.
My experience with stuff like this is when a light or turn signal is left illuminated it runs the battery down overnight,
lights in the frunk, engine compartment, glove box or the dome lights.
It tends to crop up more with an older battery that already has diminished charge capacity.

• Check all your lights are out.
• Check the cells in the battery to verify the plates are fully submerged in the electrolyte liquid.
• Disconnect clean and reconnect the battery clamps.
• Jump the car or let it sit overnight with a two amp charger to get it going in the morning.
• Once running for a half hour or so the running voltage should be 13.5 or greater volts
• Immediately after shutting the car off the battery should be at 12.5 or more volts.

If the battery is at less than 12.5 volts at shutdown it is in marginal condition and may be contributing to rundown to below a functional starting charge overnight.
If your car has an unusually large resting drain/loss you may want to consider purchasing a Volt/Ohm meter to search out the errant load.
Andy

 

pp000830, you are not correct when saying the car systems drawing higher current when unlocked. All systems will eventually shut down as if locked after some seconds.
The Climate Control Unit may have a fault that prevents it from shutting down, but beware, it takes up to 20 minutes after ignition off for it shut down. It is designed to do this to ensure correct temperature regulation after short stops.

See our web page for a DIY test procedure and details on the most common cuplrits regarding current draw, and how to find them:
https://www.bergvillfx.com/porsche-9...-measurements/
Cheers,
Tore

 

Culprit was the Climate Control Unit. I didn't have the temp all the way to the left and it was running the fan when I did a test this morning.

Thanks for the tips and tricks

 

 

X2

 

The diagnostics @Tore shared was super helpful. I thought I had a parasitic drain problem. Did Tore's tests and confirmed I didn't have it.

How hold is your battery? I had a relatively new interstate and one of the cells failed. I would charge my battery overnight and could not crank my engine that well. Brought the battery into of their "Interstate battery centers". They ran a diagnostic and within a few minutes they figured out the battery was done and gave me a new one.

 

So, I do plan on bringing the battery in to an interstate battery facility to get it checked but the nearest one is about 60 miles north of me in Denver so it's difficult to plan that hike during a work week. I'll update if I find anything on that front. Still also messing with the climate control as it does continue operating the fan after a shutdown if I do not move the temp gauge all the way to the left when I shut the vehicle off. It does shut that fan off if I enable the alarm though and leave the temp at anything other than far left.

Hopefully if I have time after work when it warms up Wednesday I'll have an opportunity to play around with the voltmeter on the individual fuses when parked to check for drain.

 

I've never heard that the temp **** should be set to full CCW position to reduce battery draw...am interested to hear the final results of this issue.

 

Final answer: The two year old Interstate battery failed. I finally had a chance to take it down to the local Interstate Battery distribution facility and they tested it and walked out within 30 seconds with a brand new battery.

Before taking it in I tested every single fuse and found the only one drawing power was the light in the frunk when I left it on intentionally to be my known variable. I also ran the vehicle with the old battery and verified that with it running I showed 14.4 volts on the bad battery. It would die within 24 hours anytime it wasn't in use or on a trickle charger.

Thanks for the quick responses though, I found it educational to dig around in the cars electrical.