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Newbie, Dead Battery... HELP.

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Hi all, newbie to Porsche so bear with me. I read up quite a bit last night on this forum regarding batteries, and related issues. It seems that usually it is either time for the battery to go, or that there are ignition switch issues.

Either way, here is my problem: Bought the car Wednesday, drove it home. No issues, stopped, started, bought gas, etc. No issues the entire 350 mile trip home. Next morning, battery dead. Jumped, drove it around to make sure it charged and parked it again in the garage. Today, after being parked for about 18 hours, dead again.

There were no lights left on, the only thing that I can think of is that I used my Garmin on the way home, and installed the cigarette lighter back in it's home on the dash. When I got in today I saw that it was pushed all the way in (as if to heat it up). Does anyone think this could possibly be the problem? Seems awfully odd.

I should also say that the battery is what appears to be the original, it is in beautiful condition, and looks essentially new.

Here are the details of the car:

2000 986, manual

27.5K miles

full service history, one owner, truly remarkable condition, adult driven / never tracked, etc.

Any thoughts?

Thanks in advance!


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Not sure what you have for a GPS but my handheld until would take two months to kill a decent battery. I doubt that is the issue, they just don't pull enough amps.

It could be do to a failing (common) ignition switch but you tend to get other issues. For example the car may have issues starting (connecting) or some systems don't get power or stay on from the contact points changing.

Sounds like you are charing fine but you may very well have a poor battery. They can die in many different ways with different symptoms. Never rule it out.

The best solution is low tech but effective. Make sure you have your radio code.

Put a voltage tester on the battery terminals and record the voltage and how slow it drops with doors open and all systems off, turn your interior lights off. Something that is draining it will be slowly pulling it down. YOu can start pulling fuses and when you get to the feature that is to blame you'll see the voltage jump up 0.1 or 0.2 volts. I've done the same thing but backwards before which is pull all fuses (did this on a Saab) and added them in one by one until something was seen to severely with the system.

If you don't have a way to test amperage this low tech way can be effective if you are systematic. As far as guessing which system is to blame, I don't have much experience with this failure or know enough of the cars history to pick it.

But for example I know the horns are prone to fail and blow out fuses. Also horns pull a voltage all the time to them but often less then 12v. Although I don't know how they work I figure they could be very well to blame if a short is leaking voltage.

Just some thoughts.

Do you have any after market stereo equipment or such that may be incorrectly wired? Something the previous owner did?

Lastly don't be afraid to take that battery to FLAPs and have them load test it, they will do it for free. I had a battery in my boat last year that would charge great and be down to 10v the next (bad cell?). I brought my $40 load tester from home and it told me the battery was failed. If you think your battery is to blame test it first.

Edited by rsfeller
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If a battery has an internal short, bad cell, it can work fine one day and be dead in the morning. Nothing is going to cure it. As rsfeller, a GPS unit does not draw enough amps to kill a battery that fast.

Get it fully charged then take it to a place for a load test.

If you need a new one then. http://www.renntech.org/forums/index.php?s...&hl=battery

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Thanks for the insights. The GPS unit was removed and the lighter was placed back in the dash. Again, that should not draw that much so I doubt it was that.

I am going to replace the battery first (it is the original, so no surprises there) tomorrow and see how it does.

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mikefocke: I actually have already used your list and ended up getting an Autozone Duralast Ultra 48-DL . The installation was easy, though it would be easiest with a second person to help guide the battery back in.

It was indeed the battery. I was able to use my battery booster to keep the electrics online during the exchange.

After a couple of days of worrying about it, it was over in 15 min!

Thanks for the advice everyone.

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