Black993

Consistently getting a dead battery. Battery isn't that old (08). If the car sits for 3 days or more it won't have enough juice to start. Just checked after sitting for about a week and the battery was at 1.2% according to my charger. I've done a bit of searching and will start with what I've found, but wanted to get the best way to test these common battery draining items (electronics isn't my strong suit):

-CDR-210 head unit
-CCU fan (don't hear it running)
-Alternator/Voltage regulator.
-Ignition switch

Will also check the trunk light, which I can figure out. Not sure the best way to test the others.

Has just recently started doing this over the last month, until then it had been great.

Thanks

95_993

Check the CCU. Known the drain battery.

IXLR8

You might have a dud battery or a faulty charging system. Another possibility is a faulty starter, starter solenoid or wiring to the starter.

You can't do any testing unless you havet a Digital Multi Meter (DMM) which can be bought for well under $50 and has uses far beyond your car. Make sure it has a 10A DC setting.

A battery's state of health is done by performing a load test and capacity test. If you are unsure about how, ask.

The charging system can be easily tested while the engine is running. Check the voltage across the battery and have someone bring the RPMs to above 2000. You should read low 14s.

Now you know why I installed a voltmeter in my Carrera. They are handy while driving and while parked...


If you suspect a current drain due to some device staying on, you can measure what it is with a DMM by placing it between the negative battery post and the negative cable. Start in the 10A mode. If the current draw is less than the next lowest current position (usually 200 mA), you can switch to that mode.

To isolate the culprit, you remove one fuse at a time and check to see if the current has decreased substantially. Reinsert the fuse and remove the next one till the problem is found.

North Coast Cab

I have the same issue. It seems at times I can hear the CCU doing somehting. It is not a cooler fan or anything, but a crackling/humming type thing. My CCU is a fairly new replacement.

Denise993

My car has the same problem ... I have to keep it on the trickle charger at all times, or I pull the negative on the battery. It's annoying.

I'm taking her to the shop at the end of the week for brake pad and will leave her with my mechanic so he can track down the drain. I'll report back on what he finds ...

Felix

Don't forget the glove box light - you can diagnose it and the front compartment light using a cell phone or digital camera in video mode to see if the light really goes off.

And the window relay sometimes sticks on - if you can operate the windows with the doors closed and ignition off something's not right.

mstolo

I had the same issue...mine was a faulty window switch. Seemed to be working fine, then the battery started draining like yours, then the switch stopped working all together, replaced it, battery drain gone. i guess I was just lucky.

Bouzoukikid

Never thought of that. Great idea

Mine last's a week. Not good enough. I have added a screw type thing to the earth and it's easy to disconnect the battery for longer periods.

TMc993

[QUOTE=IXLR8;7945214]Now you know why I installed a voltmeter in my Carrera. [QUOTE]

Alex,

That's a really well done DIY...Thanks!

Terry

IXLR8

Terry,

That voltmeter was supposed to be mounted on my BMW motorcycle, but some cell phone yapping kid wrote it off for me, so it went in the Porsche...where I could have used it earlier this year when my alternator belt failed.

It would have been nice to know how low the battery was going as I was driving on battery power for about 110 miles. Thanks to a month old battery, I made it home with the battery sitting at 11.4V.

Black993

[QUOTE=TMc993;7949417][QUOTE=IXLR8;7945214]Now you know why I installed a voltmeter in my Carrera. Indeed. Thanks!
Will start pulling fuses tomorrow on the hunt for the evil draw and report back.

trojanman

same problem here and ended up diagnosing the cdr-210 as the culprit... replaced it and no more problem

Denise993

My mystery is solved! It was the CCU fan. I couldn't hear it, but that was the culprit. Super-expensive for a new one, so mine is being sent out for rebuild.

Good luck!

Black993

So I haven't been able to get around to looking at this until this morning. Charged the battery to 100% last night, showing 12.4 this morning.

Hooked up the multimeter and the only draw I can find is .26 and it is from the fuse labeled "Interior lights". Pull the fuse and I'm down to no draw. From what I've read, that is a normal draw (anything up to .35 is acceptable, though I'm not sure about that for Porsche)

With car running at 2500 RPM its right at 14 volts with all other electrical components off.

As soon as I hook the battery up to the car, I can watch voltage drop on the meter, point by point. It went from 12.47v to 12.46v in about 2 or 3 seconds, and continued this way, discharging. I assume this is NOT normal.

Is the .25 draw my problem? Is this in the acceptable range, and why would it be from my interior lights? Hood latch shut, the light goes out. All interior lights are off, only thing I'm unsure of is engine compartment light. What else is on that circuit?


EDIT: didn't think to check the glove box light. It has been staying on. Looks like the hinge is goofy and its not pressing the glove box door into the plunger to turn off the light.
Is that enough to kill the battery in a day and a half?

cmat

What range are you using for measuring current draw? If you are reading 0.25 amps, you are way too high. You should be closer to 0.025 amps or 25 milliamps.

Just saw that your glove box light is staying on. That will definitely drag your battery down quickly.