Jump starting other vehicles

[Johnmed]

Hi all. Last summer I tried to jump start a lawnmower in France (as you do), with no luck. And today I tried to jump a friend's Qashqai thing. I wasn't expecting it to work, and it didn't! I had to tow her car to start it. She'd not done that before, so it wasn't as easy as you'd expect. But hers being a manual at least that option was available.

It got me thinking about if the D3 could jump start another car. I know the complex power management and the steel bar on the - terminal of the battery complicate things.

So, is it possible?

[paulrstaylor]

Originally Posted by Johnmed

Hi all. Last summer I tried to jump start a lawnmower in France (as you do), with no luck. And today I tried to jump a friend's Qashqai thing. I wasn't expecting it to work, and it didn't! I had to tow her car to start it. She'd not done that before, so it wasn't as easy as you'd expect. But hers being a manual at least that option was available.

It got me thinking about if the D3 could jump start another car. I know the complex power management and the steel bar on the - terminal of the battery complicate things.

So, is it possible?

Yes - Positive to the battery, neg to the big metal post, used to do it loads in my D3

In the D4 you have a +ive and -ive terminal under the bonnet, although the battery is in the boot under the spare wheel! Works just the same

[Johnmed]

I wonder why mine isn't kicking out enough juice then? I have tried two different sets of jump leads.

I've had better luck when jumping the D3 itself, after flattening the battery with VCDS (you live and learn).

[Delboy]

I haven't read the manual about giving a jump but i suspect the battery managers diodes are preventing it from working properly, is it not the case of receiving a jump or charging it goes to the post, giving a jump is direct on the battery posts engine running preferably?

Defo read the manual though as i could be wrong

[Adrian E]

Also note that tow starting a modern manual is not recommended - it results in a lot of unburnt fuel in the catalytic converter which can damage it (assuming it's petrol!)

The usual barrier to a successful jump start is decent thickness wires. I've used my S8 to jump start a Rover 220 which was pretty straightforward, but if the car has a chunky motor or is a diesel it needs a really good battery and thick cable

[Johnmed]

Originally Posted by Adrian E

Also note that tow starting a modern manual is not recommended - it results in a lot of unburnt fuel in the catalytic converter which can damage it (assuming it's petrol!)

The usual barrier to a successful jump start is decent thickness wires. I've used my S8 to jump start a Rover 220 which was pretty straightforward, but if the car has a chunky motor or is a diesel it needs a really good battery and thick cable

I didn't know that about tow starting a modern petrol. Thanks. I used my leads and my friend's. Both have worked to start her car and the D3 previously.

[snapdragon]

TBH, I wouldn't use the post for jump starting another car, just the battery terminals.
I think you only use the post for charge monitoring and maybe charge reulation (cut off) but it would be good to know for sure..
(I wouldn't even use it for jump starting the A8 itself)
Most jump starting problems are caused by the jump cables being to thin and long. That's why they are sold as 'booster' cables.

[Johnmed]

OK, just had a look at the manual. From what I can gather, it only mentions attaching jump leads to the (-tive) metal bar and +tive terminal of the D3.

I didn't see guidance anywhere saying that you could attach a lead to the -tive terminal. I'm busy at the moment tho, so I may have missed something in my haste.

When jump starting another car it suggests attaching the -tive lead to the engine block. (I tried that yesterday, to no avail.) So, Im still no clearer as to why it wouldn't work.

[Mechcanico Lee]

Be careful here , leaving the engine running on the jumping car can cause its alternator to go to full load in an instance as the dead cars starter cranks over .
The dead car because of its flat battery doesn't have the same 'buffer' effect to calm the surge down .

I've seen quite a few of ' my alternators packed up now since jumping my mates car '
The a8 having battery monitoring may be able to deal with this effect better than others though

[Johnmed]

Cheers chaps.

SEEMS NOTHING IS SIMPLE THESE DAYS!