M1ndfr3ak

Hello.
My Audi S8 D2 battery recently died because I forgot to turn off the lights and now I am facing a problem: the trunk won't open and I have no idea where the jumper post/box is located under the hood. Cannot call the service either because of the holidays and some random car trouble companys just tell me to look near the windshield.

So, where is the jumper post or box located under the hood and what does it look like.

SCL

Did you find your answer? I have a couple suggestions. You can clamp the positive jumper cable to the starter (not so easy) or to alternator if you can get at it, although the gauge of the conductor from the alternator to the starter is smaller and may heat up if you try to start the engine. But if you allowed the dead battery to charge for a few minutes, the alternator conductor would be relieved of some of the work.

The other suggestion is to charge the battery thru the cigarette lighter, or thru the fuse box, at least enough to start the car. The lighter fuse is only good for 30 amps, so if you were to jump start the car thru the lighter I think the fuse would pop. But the battery will charge this way (unless the cigarette lighter is switched with the ignition). You can also plug a paper clip or stiff wire into one of the fuse receptacles to have a way to put voltage on it. You'd have to know which side to connect to though, and do not connect to a circuit that you do not want to have power, such as the engine ignition or lights or wipers.

I have found that a great DIY battery charger is a common laptop charger. Those (older) black IBM power supplies, for example, put out 16 volts at 4.5 amps. The newer Lenovo PS's put out 20 volts, so I would not use those unless I had no other choice. The charger can be higher than 12 volts...something in the 12-16 Volt range works fine. To use my laptop charger or something with a similar connector, I push a wire into the middle of the charger connector (positive) and wrap a second wire around the outside, and tape it up. You can put a voltmeter on it if you are not sure of the polarity. And when connected to the car battery, the voltage will drop to around 12 volts. Other consumer chargers in the 12-18 volt range will also work, but most chargers are 100-500 mA so would require an overnight charge. Obviously these chargers are not made to charge a car battery, so I would not leave it unattended and do not leave it connected for an extended period of time.