Can I help my mate jump start his focus with my E39? Urgent.

[sparks_E39]

I am with him now. By using the battery in the boot? I thought the terminal in the bonnet was only for jumping my car. I don't want to damage the electrics in my car...

[Loominarty]

No problem. Crack on.

[Loominarty]

No problem. Crack on.

[Stu R]

Used my E38 to jump a mates focus and another mates punto, no probs with either - yes battery in the boot is fine too

Edited by Stu R on Saturday 29th October 17:36

[IainZ]

sparks_E39 said:

I am with him now. By using the battery in the boot? I thought the terminal in the bonnet was only for jumping my car. I don't want to damage the electrics in my car...

Suggest connect it straight to the battery in the boot.

[Robb F]

You can just disconnect the battery from your car and use it. No risk to your car then.

[sparks_E39]

The positive is by the red cable in the boot right? It's a Bosch and its not marked. Thanks

[E30M3SE]

Yes, red cable, but just use the connection under the bonnet.

[sparks_E39]

Thanks all, we used my battery connected to the car, alas Focus is still dead so I've done what I can

[Cemesis]

For maximum cranking power, your car needs to be running.

Start the car, let it run for a minute, turn the sidelights on and then connect it to the other car using the terminals under the bonnet. Then try and start the Focus.

[phumy]

Cemesis said:

For maximum cranking power, your car needs to be running.

Start the car, let it run for a minute, turn the sidelights on and then connect it to the other car using the terminals under the bonnet. Then try and start the Focus.

Why turn on the sidelights? Is that side kind of magical sign?

[sparks_E39]

Engine was running and we tried for around ten minutes, didn't have the lights on though.

[Pothole]

phumy said:

Cemesis said:

For maximum cranking power, your car needs to be running.

Start the car, let it run for a minute, turn the sidelights on and then connect it to the other car using the terminals under the bonnet. Then try and start the Focus.

Why turn on the sidelights? Is that side kind of magical sign?

no it's something his (insert dozy old codger details here) told him and he's never questioned it.

[Cemesis]

You do get some witty people on here don't you. To avoid potential voltage spikes which can damage modules in the car you can turn the sidelights on. Not an electronics engineer so cannot be sure of the effect but I'd sooner do that than risk toasting a unit.

If you tried it with the the engine running thats all you could have done.

[rumple]

phumy said:

Cemesis said:

For maximum cranking power, your car needs to be running.

Start the car, let it run for a minute, turn the sidelights on and then connect it to the other car using the terminals under the bonnet. Then try and start the Focus.

Why turn on the sidelights? Is that side kind of magical sign?

its the thing to do, prevents any overload whilst jumpstarting, ive knackered a ecu jumping someone, only do it if the cars gonna start, i did a old sherpa van and cost meself alot of bucks

[gizlaroc]

You want to use the jump terminals under the boot and not direct to battery, unless you have disconnected the positive terminal, on any BMW from this era onwards.
You can easily fry your ecu modules going direct.

[bmthnick1981]

Jump started my Clio with the battery in the boot of my E38 today. No problems.

[MarkwG]

gizlaroc said:

You want to use the jump terminals under the boot and not direct to battery, unless you have disconnected the positive terminal, on any BMW from this era onwards.
You can easily fry your ecu modules going direct.

Yep, paricularly e39s, as there's an explosive bolt which disconnects the battery cable in the event of a shunt inline with the positive cable; it has been known to trigger under such circumstances. Requires a new loom (& new underpants) to fix.