Porsche Enthusiasts Club Forum

As you can see from the following photo, I have been a busy geek: I now have a tiny 7" netbook as a car MP3 player. This is bluetooth controlled from my phone. A line-in to the back of the Sony head-unit is on the top-left of the glove box. On the top-right is a 12v supply from the battery with an illuminated switch (also fused near the battery). I then dismantled and reassembled the netbook's miniature 2 amp car power adapter (now sitting on top of the netbook).

I was very happy with this at the weekend. Today however, I couldn't start the car. I had the netbook and the head unit on. Power was going to all accessories, and the battery is brand new. The start position on the key yielded nothing. Not even a click from the starter motor solenoid. So I turned off my red switch supplying power to the netbook. Car started perfectly!

How is a 2 amp draw interfering with the starter? All my connections are insulated crimped bullet connectors, or soldered and shrink-wrapped . My new power wires go through the firewall grommet with most the standard loom. I welcome your thoughts on the problem, or just your geeky appreciation!

From experience with older cars, the starter motor usually uses quite a bit of power and if any electrics are on, they usually dim or switch off temporarily while the car is started. Have you checked that your battery terminals are clean and tightened up? you can use some vaseline on the terminals to help contact. Personally, I wouldn't worry about it - just treat it like one of the quirks of owning an older car and make sure you start the car before turning any electrics on.

Other things to think about are, are you sure your altenator is charging the battery correctly? Maybe you have an electrical fault somewhere and it leaks power (for example - an interior light that doesn't switch off) when not in use and therefore drains the battery before start up?

Hope you enjoyed my help...lol...maybe I could be a mechanic after all

You don't have to worry about the glove box light, a usual culprit for power drain

Sean Smallman wrote:You don't have to worry about the glove box light, a usual culprit for power drain

Incidentally, this doesn't work anyway, even with a new bulb.

I was concerned that I had shorted something out, and that turning my switch on with the car running will blow up the ignition or something ridiculous!

Advice is always good Kat!
The battery is definitely charging, I've had it a month or so now, and the engine turns over really fast since the new battery.

the starter motor usually uses quite a bit of power and if any electrics are on, they usually dim or switch off temporarily while the car is started

Yup, certainly, so a 2 amp laptop transformer should simply be cut off when the starter motor is engaged. The car can quite happily start with the radio and lights on.

UPDATE: I had a chat to my auto-electrician today. He reckons my netbook power adapter is interfering with the immobiliser, either through a noisy transformer, or a possible ground loop via the audio connection and the head unit.