Battery light coming on!

[geoff]

Driving home through the canyons from the German AutoFest in Ventura, my battery light came on a few times. On solid for a few minutes, then went out for a minute or two, then back on for a while. Original battery on a 2001 2.7 5 speed. Never had any problems starting, don't use battery maintainer, battery never drained, no radar detector, doors never locked at home, so basically no drain from alarm. Owners manual says it's either "defect in the battery charging system or broken drive belt" - no real helpful at narrowing down the problem. Car wasn't overheating.

Any thoughts / suggestions? I'll call the dealer in the AM (it's not under warranty - 4 years were up in February), but better to be armed with some knowledge in advance.

[spine911]

Its either a bad Alternator or Battery. Id first bring it to your local Auto Zone and have them check your Battery and Alternator(Charging) for free. They can tell you whether either of them is failing.

[geoff]

Here's the update so far; I'll provide the answer when I find out...

Car sat from Monday to Thursday in my garage when I was out of town. Spoke with the dealer service manager on Friday - couldn't get in, but he suggested hooking up a battery charger, or at least the Porsche battery maintainer (I used the battery maintainer). Car had been starting just fine, but figured it couldn't hurt.

Go out for a drive on Saturday. Car starts fine, but battery light is on. Drive a few miles, during which the light occasionally goes out, then comes back on. Head up a canyon road, then the ABS light comes on, then a little while later the airbag light comes on, go into a tunnel and all dash lights come on and the car dies. Coast over to the side of the road, car won't start. Didn't lose the radio code, and fortunately the emergency flashers still worked.

Flatbed tows are expensive ($8 / mile) after the free AAA 8 mile tow :o

[Loren]

From the service manual:

Battery warning light

Lights up as a check when the ignition is switched on. If it lights up with the engine running, stop the vehicle immediately and switch off the engine. The cause can be a fault in the battery charging device and/or a torn drive belt.

[geoff]

From the service manual:

Battery warning light

Lights up as a check when the ignition is switched on. If it lights up with the engine running, stop the vehicle immediately and switch off the engine. The cause can be a fault in the battery charging device and/or a torn drive belt.

<{POST_SNAPBACK}>

Dealer service manager said to keep battery charged (or at least use the Porsche battery maintainer) and drive it in when I get a chance. Said no problem driving it in the meantime. What he should have said is no problem driving it until it completely dies! :(

[ar38070]

Flatbed tows are expensive ($8 / mile) after the free AAA 8 mile tow  :o

<{POST_SNAPBACK}>

Subscribe to the AAA Plus service. You get up to 100 miles of free towing.

[geoff]

Dealer service manager called today after they looked at the car. It started for them, but the battery light was still on (good that they could quickly see the problem). Alternator has gone bad and needs to be replaced. 4 1/2 years old, just under 38K miles. Replacement alternator is $900+ for a rebuilt one, or over $1,100 for a new one :( Labor to install is extra. This sounded ridiculously high, so I called Sunset, and was quoted $607 for a rebuilt one and $795 new. Ouch!! I'm on the east coast for the week, so not much I can do now except eat the cost.

They said I probably will need a new battery also, but this sounds like a good excuse to get an Optima if the battery has problems.

Is there anything else I should have checked or done with the alternator being replaced? Serpentine belt?

Thanks

[spine911]

Piece of advice to save you $$$ with your Alternator issue...ALMOST ALL Alternators that are sold by a part shop or your local Porsche dealer are Rebuilt. Rebuilt Alternators also carry some warranty(approx. 6mo-1yr) depending on the dealer. The quality of Rebuilt Alternators are as good as your Brand New Alternator....I once purchased a Rebuilt Alternator from VERTEXAUTO.COM(Miami,Florida) for my 86 944 which i completely rebuilt about 4yrs ago(4yrs/85k miles since) and still performes like Brand New...Another alternative would be to find a local Starter/Alternator repair shop(Auto Electric Shop) in your area and have it rebuilt.--will probably cost you below $150 to rebuild(same quality with warranty as well). Rebuilding/Reconditioning an Alternator is not Rocket Science and is extremely cheap/and easy to repair ...Im sure your local Porsche Dealer would take your core to be rebuilt by a local shop and resold for 10x the orig. repair cost....Having owned 3 previous Porsches before my Box, ived saved tons of $$$ just ordering quality Porsche parts from VERTEXAUTO. They are very knowledgeable with Porsches and has competitively priced high quality parts....BTW, any reputable independent Porsche repair shop can install a 986 Alternator besides the overpriced $tealer.