ricm

This has been discussed ad nauseum, but once again, here's my ongoing adventures with battery drain ('09 997S).

Business abroad for twelve days in April, I returned to a dead battery. With cold weather and an after-market battery, I installed a new one (Walmart). PASM would not reset so a visit to the dealer for reprogramming. All good.

Returned yesterday after two weeks abroad to another dead battery. Drove the car about 25 miles the day before departure (and 1200 miles since the last episode) and left it in sleep mode. I assumed it would be fine with a new battery and ambient 90-100F temps No luck. Trickled it for about 12 hours, started the car and drove it about 25 miles. The airbag light is on so back to the dealer it goes.

The dealer states that they aren't surprised and that I should ALWAYS trickle charge for "prolonged" downtime. Defined: FIVE DAYS or longer!

Called PUSA - they recommend driving the car at least 15 miles/day or trickle charge for "prolonged" downtime. Defined: A week or longer. And battery drain occurs even in "sleep" mode.

I can see the flames coming and the expected yuck-yucks that these vehicles are daily drivers and expected/acceptable for such a stellar marque. But it's amazing that P can't engineer a vehicle that will withstand down times longer than a week or so! And specify that a CTek is MANDATORY and include one as standard equip with the battery harness preinstalled.

Upcoming visit to the dealer for more reprogramming and a check of the electrical system/battery.

Cheers!

schip43

Hmm well I have a 85.5 944 and a 89 TS...it sounds like nothings changed battery wise.

petee1997

Why do you refuse to use a battery tender. My car is plugged in unless I plan on driving it daily. The car is flawed and no amount of complaining will solve the problem.

GSIRM3

What is sleep mode? Doors locked or unlocked?

No HTwo O

For the car to go into sleep mode, the doors need to be closed, locked and the alarm activated. After about 5 days, the car enters sleep mode to save battery life. You will not be able to open the doors with the remote key fob. You need to unlock the door with the actual key, and within about 30 seconds you need to insert the key into the ignition, and turn to position 1. If not within about 30 seconds, the alarm will sound. You do not have to actually start the car. This reawakens the car. It will go back into sleep mode again in about 5 days.

To circumvent the sleep mode, you can "awake" the car prior to day #5 with the key fob, by just giving it a quick lock or unlock (remember, it will re-lock itself if a door is not actually opened).

Bob112233

AFAIK, there should be nothing mysterious about it.

There is a specified amount of current the car is supposed to draw when it's been parked long enough for it to go into "sleep" mode. If it draws more than that, then there's something wrong.

Get that info from the dealer (it's in their service manual) and then measure it yourself with the ammeter in your VOM meter.

FWIW: http://www.ehow.com/way_5218043_volt...-tutorial.html

BTW, I always use a QUALITY battery maintainer for my cars (CTEK is industry standard AFAIK). Why not have the battery always keep it's full charge: can't hurt.

ELUSIVE

Battery maintainer for me if the car sits for more than 5 days.
Do you have anything aftermarket installed?
I had some battery issues with my Tooki Bluetooth module. Even when the car was off, it was searching for my phone and killed the battery. Nav/TV replaced the unit with a newer model and i've been pretty good since.

Battery maintainer is just piece of mind and super easy to stick into the cigarette lighter outlet.

Para82

I'm not surprised. My 997.1 sat for 5 months came back to a dead battery, replaced it - still had issues. Front end electrical had to be replaced. Roughly $940 at the dealership. No issues since but I make sure to use the Porsche trickled now for anything longer than a week.

Bijan

My 09 997S would start easily after 3 weeks of non driving, with many original options and battery. I do now use the CTek maintainer but only for a few days if idle for more than a week.

USMC_DS1

I plug in the CTEK every day out of habit. I fly out of town on business every other week typically for 3-5 days. No problems after 18 months of ownership. BTW, I did not have a trickle charger on my old M3... always had issues. Felt the same way the OP does about the Porsche but towards my M3. Now my '92 Toyota 4Runner is a different story. Leave it for a month or two and start her up... fires right up. Of course, the 4Runner has minimal electronic wizardry. Get a trickle charger and all will be much improved.

Yet anothercrisis

It is really aggravating that we have to give in to poor engineering and keep these cars on a trickle charger. Corvettes are bad too. So bad that many on the forums use a Priority Start. It hooks to the battery and isolates it after the voltage falls so far but not so far as to fail to start. I don't see the Priority Start mentioned here for the Porsche so I have not tried one on my 997.2. I am afraid that the results will be to affect something that would not be under warranty.

I, too, have other cars, some with what seem to be the same amount of electronic wizardry and they never fail to maintain a charge. I left my new Subaru Outback unplugged and untouched for three months this spring and it started right up when I needed it.

It is sad that Porsche handles this as though it is our problem.

Fred R. C4S

You should try driving a Ferrari! Porsche treats you like the king of the world compared to the Scuderia. I guess it's all relative depending upon the view from where you stand.

Spokane5150

Well, I took my car in last week for this problem and they replace the alternator and a starter cable. I didn't realize the car would turn over so fast. Does your car turn over slow all the time? As you may already know....Low voltage causes the air bag light. See below: Technical Bulletin

The battery tender that Porsche makes that plugs into the lighter socket near the foot well is the best way to go. http://www.suncoastparts.com/product//95504490054.html

Per Porsche's technical bulletin.

Issue: Battery discharged and/or will not charge properly. Voltage drop due to alternator-starter-battery harness damage at starter terminal. This issue is often mis-diagnosed as a bad battery, bad alternator, or bad starter, and these parts are often replaced in multiple repair attempts before the harness is determined to be the cause of the issue.

Before ordering or replacing other parts, have the car professionally inspected. Check the voltage drop between the alternator and battery. Bring the car to normal operating temperature. Turn on as many power consumers as possible (AC, headlights, radio, defroster, etc.). Use the same grounding point for the following voltage measurements:
- Measure the voltage at the "B+" terminal on the alternator.
- Measure the voltage at the battery positive terminal.

If there is a voltage drop of greater than 0.5 volts between the alternator and the battery, and all of the connection points are tight, check the harness terminal at starter. It is possible that the crimps on the starter terminal where the two cables are joined together incorrectly, causing an excessive voltage drop between the alternator and the battery. This voltage drop does not allow the battery to charge properly, and as a result, the battery will continually discharge until it will no longer start the vehicle. There may be no visible damage to the harness, and more measurements may be necessary to determine which cable or part of the cable is responsible for the voltage drop.

ricm

Thanks! I'll mention this to the service writer.

ricm

Nothing other than an Escort hard wired to a switched circuit which I unplug when I leave.