johneecatt

Went to jump in the car this morning to go down to the shop to do some brake work. And the battery (just a few months old) was stone dead - nothing! Had to carefully open the door, because the window wouldn't drop. So I hooked up another car to jump it. Now the windows and dash worked, but not enough juice to start the car. Left the other car run for about 15-20 min, then I could start the Porsche, and it ran fine.
But what would cause this? I drove it on Saturday, got it up to temp, got gas, etc. After I gassed, got an ABS CEL, but that went away after a minute or two.

What would drain a relatively fresh battery completely dead after sitting for two days?

Ahsai

It doesn't have to be a large drain. Our battery has about 70Ah capacity. Even the drain is 1A, the battery will be low enough that it can't start the car.

Any aftermarket accessories on the car? Forgot to unplug something? Fastest way is to use a clamp meter to check the battery cable
Could also be a bad alternator (you can clamp the "+" main cable in the engine compartment to check that).

Hurdigurdiman

If the car was left unlocked, that too could drain a battery. I believe when cars are left fully locked up, the battery uses less juice than it does to keep the car unlocked. I suggest that you recharge your battery overnight.

Gonzo911

Could just be a bad battery. Take it back to where you bought it and have it tested (should be under warranty).

Then hope and pray that it is just a bad battery.

rainmn

Really? I'd like to hear more about that one, and what specifically causes the drain on an unlocked car...and what the hell Porsche was thinking if it is true.

My car spends the majority of time in my garage (I work from home), and it's never locked.

psha8224

I've had similar issue. New (Oct.2014), dead after 24 hrs. of non-use. Bought car (2002 996) a month ago.
Clean (?) PPI - E-Mail to PPI Indy shop:

On 3/2/2015 I brought in a 2002 Porsche 911 for a pre-purchase inspection (your invoice #000088134).
There were a couple of observations but apparently noting mechanically earthshaking. However, there were two faults identified by the Autologic Diagnostics test:

Instrument Cluster 23 - 9130 Power Supply

Alarm System 148 - 42 Wrong key or wrong transponder pill.
21 W lead (DME immobilizer), open circuit.

There was no comment or recommendation in the written report or during our discussion.
I’ve found that my battery drain after only one day of leaving the car idle requiring a call to AAA for a start. Luckily, I have a trickle charger which keeps it charged but there is clearly an electrical issue.
Since the only fault codes seem to have an electrical system relevant I suspect that one or more of these may be the source of the problem.

I need to know how to interpret these fault codes as Porsche fault codes as they merely list parts numbers.

Response from Indy: I'm just confirming that I got your email and I will ask the tech about the fault codes that were in the computer system when we performed the PPI on the Porsche.

23-9130 normally means that sometime in the past the voltage to the car's system was low enough to trigger a fault code that the instrument cluster didn't have enough power to run properly. The car's computer does not retain a date of when this problem occurred and if no complaint was logged about the instrument cluster the first step to reset the code and see if it ever returns. It is common to see this fault in used cars sitting on car lots because the battery will go dead at the car lot due to non-use.

148-42 tells us that someone tried to start the car with the wrong key or the key transponder failed. (Are all your keys working okay?)

14-21 is the one that I'm not sure about. I will have to ask my tech what that one means. However I do know that the immobilizer is the alarm computer and if faulty your car would not start at all.

I'm currently in Europe for two weeks. I disconnected the battery to maintain a charge while I'm gone.
Hopefully no negative issues as a result - (no radio code due to after-market radio and amps).

I'll be interested in any further info./outcome.

johneecatt

Thanks for this info. We'll go over these codes, and I'll get back to you with what I find.

johneecatt

I've heard of this (in the Cayman forum), but I think it's a matter of weeks, not days.

In any event, it was locked.