I've not used 964 for 5 weeks - it's 125 miles away. If it has a flat battery tomorrow morning I will use, unless I'm told not to, jump leads to start it. But it's years since I've used them and I can't remember the order of play re. which lead to attach first etc. etc.

What's the correct procedure? Thanks in advance!

Piers
1990 C4 Coupe
PS Can I push start it?

 

Piers

I had to do this recently when mine ate its battery after 3 weeks in Thailand (it was me in Thailand, not the car obviously. I don't mind paying £££ to give the car TLC, but not yet at the stage where I am sending it on holiday. Well not without me anyway).

You attach the cables with the ignition off - this is most important. I don't know if it makes all that much difference which order you connect the cables, but I believe I connected both the pos and neg on the 'feeder' car and then connected negative followed by positive onto mine.

 

Typically when you use jumper cables the proceedure is:

1. (+) or red terminal of donor (good battery)connected to the
2. (+) or red terminal of recipient (bad battery)
then
3. (-) or black terminal of donor (good battery)
4. (-) or black terminal TO A GOOD BODY GROUND NOT THE BATTERY POST.

The last connection (the ground) may 'spark' when connected. Do not ground to a painted/finished surface. I try to ground to the frame or a fastener (bolt head.)

The donor car should be running. It helps to gently rev the engine of the good car for a few minutes to allow the current to 'flow'.

Good luck.

Install a battery disconnect switch and buy a battery maintainer to avoid the problem in the future.

marc

 

Hi Piers,

The procedure for jump-starting your car is in the owner's manual. I believe it pretty much mirrors what Marc has written above. Just to be extra safe/careful, I always follow the owner's manual instructions (manual opened to the appropriate pages) when jumping my 911.

 

Thanks guys!
BR
Piers

 

I believe Marc has the basic sequence exactly right (secure both positive connections first, then secure the negative/ground connections).

The reason for this sequence (which might help a person recall the sequence when no manual is handy) is to minimize risk of accidentally creating short circuits as one handles the jumper cables.

If one connects the cables to both terminals (+, -) of the donor car before connecting to the receiving (dead) car, then there is a risk of creating a short circuit by accidentally brushing the free cable ends/claws together while connecting them to the receiving car. Connecting both positive ends of the cable before connecting the negative/ground ends prevents this.

The reason one connects the positive ends of the jumper cable before the negative ends is because most metal objects in the car are connected to ground (if anything). If the positive leads are connected and you are connecting the last negative lead, then if you accidentally brush that negative cable end/claw against something, chances are it will be grounded so the circuit will be completed properly with no short circuit. On the other hand if the negative leads are connected and you are connecting the last positive end of the jumper cable, then if you brush that positive end against something metal, most likely it will be grounded and sparks will fly because you just created a short circuit.

 

Marc,

Why not connect to the negative post of the receiving (dead) car?

 

I think they advise to connect to a ground away from the battery to avoid a possible spark near the battery. It shouldn't be a problem, but it is good to be extra cautious around things that can explode.