Audi S5 2015 wont jump start other cars - why ?

[Tom_GGG]

Ive got an Audi S5 2015

Ive used the + and - terminals, details as per this article / diagram - https://www.auditech.org/acont-581.html

But when i connect the leads to another vehicle it seems as if no power flows to the other vehcile. If i jump the same other vehcile using a portable battery pack it works fine, which makes me think the audi is not outputting any power.

I note in the above article it states that "The two jump leads must be connected in the correct sequence." but this article is about jump starting the audi, not jump starting other cars from the audi.

Is there something im doing wrong / something else i need to do to allow the audi to jump start other cars ?

[bigandclever]

Are you doing this..?

If jump-starting another vehicle, you should not connect the negative lead (–) to the negative terminal of the discharged battery, but directly to the engine block or a solid metal part bolted to the engine block.

[Tom_GGG]

bigandclever said:

Are you doing this..?

If jump-starting another vehicle, you should not connect the negative lead (–) to the negative terminal of the discharged battery, but directly to the engine block or a solid metal part bolted to the engine block.

The audi is the charged vehcile. I connect to the + / - on the audi and then to the + and chasis on the flat vehicle. Is that not correct ?

[cuprabob]

Are you using good quality jump leads?

Sounds as if there is too large a volt drop either caused by bad connection and / or the wire gauge of the jump leads being insufficient for the current drawn.

[bigandclever]

Tom_GGG said:

bigandclever said:

Are you doing this..?

If jump-starting another vehicle, you should not connect the negative lead (–) to the negative terminal of the discharged battery, but directly to the engine block or a solid metal part bolted to the engine block.

The audi is the charged vehcile. I connect to the + / - on the audi and then to the + and chasis on the flat vehicle. Is that not correct ?

Well, I was attempting to clarify your linked article is also about jumping another vehicle from yours, at the bottom.

[Tom_GGG]

cuprabob said:

Are you using good quality jump leads?

Sounds as if there is too large a volt drop either caused by bad connection and / or the wire gauge of the jump leads being insufficient for the current drawn.

Could i test this with a volt meter by connecting the leads to the + - on the audi and then reading the values on the other end of the leads ?

If so what value should i expect to see on the volt meter ?

[Belle427]

Roughly the same as you would see across just the terminals.
I'm guessing it's as suggested,they can't pass the required current to start the car.
Normally its because the cable is too small gauge or the clamps are not making enough contact with the terminals.

[ninjag]

Tom_GGG said:

Could i test this with a volt meter by connecting the leads to the + - on the audi and then reading the values on the other end of the leads ?

If so what value should i expect to see on the volt meter ?

You should be able to test across the terminals of the discharged battery whilst connected to the booster car and it's running. I would expect to see between 13-14V as that is also what your booster car should be showing across the battery whilst running.

You could also do a continuity test of your jump cables first to make sure there are no breaks.

If not already done then you may have to leave it connected and running for a while first if the battery had been heavily discharged. If it still doesn't work then the battery may dead from damage / wear or worst case the alternator may be faulty.

Could even be a damaged or loose ground somewhere in the flat battery car. You could always pop your own good battery into the car temporarily to check all this.