fpena944

Going to pick my car up today from the dealer and they said it needed a jump this morning.

Battery was just replaced about 8 months ago, it is always garaged so no temperature extremes. Battery was a high quality brand but wondering, what would cause a battery to start losing the ability to hold a charge so quickly? Or was this just an instance of something being left on accidentally?

Never had any indication that there were any problems as the truck always starts right up without incident. So what might be happening here?

Tom M

My battery "died" one time overnight and when I measured the voltage it was in the 3's so really not good. I stuck it on a charger and it ran w/o incident for another 2+ years before I finally replaced it.

Any 3rd party electrical items that could draw power without shutting off?

CAVU

Possibilities:

1. Alternator is on the way out.

2. Luck of the draw battery going bad

3. If they were diagnosing or servicing the vehicle that required the ignition to be on and they did not hookup at least a 40 amp battery charger power supply (seems it is now much higher, 70 amps? anyone?), then that can run the battery down pretty quick. Left in that state over night with parasitic drain, it might have needed a jump.

4. #3 and they fired up your music maker to the maximum base pounding mode

Hope that it is just a one time event.

fpena944

Now they're saying the vehicle needs to be on the charger continuously and will require jumping before I take it home. WTF?

I basically have no choice here and need to have them replace it. It just sounds suspect because again no issues before this.

EDIT - Decided I'll just take it home and return the battery I installed previously. Don't want to purchase a new one when the old is still under warranty.

CAVU

I am suspicious by training and nature so I am not trying to drag you down.

You are on the right path to take it home. Ask them to provide you a copy of the battery test and alternator report since they are wanting to sell you a new battery and being a professional shop they would have tested the battery and alternator. You might give the car a good looking over with it running, test the jumper points under the hood for output voltage before signing for it. If the charging voltage is about equal to the battery voltage then something has happened in the charging circuit. If the charging voltage is down by about 1/3, 8-9 volts, then someone crossed up the jump cables and took out one of the diodes on the alternator.

garrett376

The dealer has fancy inductive current drain equipment that ties in with their PIWIS system to determine if there is current drain when the Cayenne is just sitting. It takes them very little time (5-10 min) to assess "if" there is a drain. Finding it would of course be a different story, but at least you know "if" there is a drain, or if your battery is just a dud.

fpena944

They did offer a test of some sort but at just under $300 didn't want to have them run it as I hadn't observed any symptoms of electrical issues before taking it in.

They had to jump the CTT when I arrived to pick it up.

I drove the car home about 35 miles. Kept an eye on the voltmeter which was registering 13.5v during the whole trip.

Once I parked the car I went ahead and shut it off and then a couple of minutes later restarted it. It started without incident so hoping that it is now holding a charge.

Now I'm going to give them the benefit of the doubt and assume that maybe they kept the ignition on overnight and killed the battery (my wife did that once) because since we have the dummy key in the ignition that can happen. The other thing I observed is that when vehicles are parked in the garage overnight they usually keep the tailgate and/or hood open. Not sure if this can cause voltage to get drained but maybe that might have something to do with it.

In any case I'll see what it's like in the morning and see if this was a legitimate problem or not.

fpena944

It started right up this morning after sitting in the garage overnight.

Having a hard time believing my battery wasn't holding a charge at the dealer now.

CAVU

Very glad that you trusted your instincts and that all is well, battery wise. You might put it on a CTEK or other "smart" AGM charger for a few nights to bring it up to full charge.