Starting vehicles with a jump pack ?

[Smallfry]

I have a NOCO jump pack, and it works a treat. I have used it to start several different vehicles with no bother, BUT............

I am being told by various people that they can cook ECUs, unless the negative lead is directly connected to the engine/gearbox (I don't imagine anything on positive earth has an ECU)
The leads on the unit are way too short to do this, and there is nothing in the operators manual regarding this.

So, is this "a thing" ? First I have heard of it, and if it is a risk, I will have to stop helping anyone, as I don't want to held accountable !

Any ideas ?

 

[Morrisman]

I can’t see how it could possibly cook anything, it’s simply putting 12 volts or so into the system, like the original battery does.

 

[Smallfry]

I can’t see how it could possibly cook anything, it’s simply putting 12 volts or so into the system, like the original battery does.

This is exactly what I thought. Even the vehicle battery when charged is capable of delivering a lot of amps, so I cannot see any difference either

 

[optima21]

it used to be that if jump starting from another battery you didnt connect the batterys together directly as the current could damage one and by connecting one of the leads to the engine/gearbox, would introduce a tiny amount of resistance to stop this happening. this would depend on the quality of the jump leads though

 

[Kayos]

I was trying to jump start a tiny Corsa with my Discovery, twin 110ah batteries.

Would not spin it over until I put the negative on the engine, then it turned over like a 1ltr Corsa with 2 110ah batteries

 

[Johnnybravo]

There probably is something to it. I remember in the 1990’s having a E30 BMW 325is and that had a whole procedure outlined in the owners manual on what you had to do if you wanted to jump start it. Headlights on etc to load it up as much as possible, supposedly to protect all the ecu’s it had in it.

 

[brightspark]

nowt like a good surge for knacking stuff

 

[qwakers]

I was trying to jump start a tiny Corsa with my Discovery, twin 110ah batteries.

Would not spin it over until I put the negative on the engine, then it turned over like a 1ltr Corsa with 2 110ah batteries

bad engine to body or body to battery ground then.

 

[Kayos]

bad engine to body or body to battery ground then.

No idea, the stupid thing was blocking the road. Plan B was to use the Disco to drag it out of the way

 

[Agrismith]

Several makes recommend switching sidelights on to avoid any damage.
Vauxhall movano/Renault master if you muck up the connection when getting ready to jump start then you have to take the passenger footwell apart to access the battery (jump points are under the bonnet) take the terminals of the battery and hold them together. It resets something.
I have no idea the reasons why it went have 5 Renault masters and have had to do it quite a few times.

 

[sg66]

Jump packs are safer than jump leads from another car, they don't supply power till it senses power draw, jump leads and smart alternator throw out power instant it's connected.

 

[Red'n'Black]

I was always taught to make the neg connection to the dead car last, and to the block rather than the battery terminal so any sparks happen well away from the cell vents.

Apart from that, I've never bothered with any special precautions. Automotive electrics are spec'd to cope with much worse than a jump start, google 'load dump' if you want all the gory details.

 

[Ubique]

I have a NOCO jump pack, and it works a treat. I have used it to start several different vehicles with no bother, BUT............

I am being told by various people that they can cook ECUs, unless the negative lead is directly connected to the engine/gearbox (I don't imagine anything on positive earth has an ECU)
The leads on the unit are way too short to do this, and there is nothing in the operators manual regarding this.

So, is this "a thing" ? First I have heard of it, and if it is a risk, I will have to stop helping anyone, as I don't want to held accountable !

Any ideas ?

The starter battery is a capacitor, electrically, so any 'spikes' caused when the vehicle starts and the alternator kicks in will be minimised by it. Any jump leads / jump start battery should only be connected to the provided connection points, connecting anywhere else may cause problems with the battery monitor system. All 'modern' vehicle control units are designed to accept a forward voltage of at least 30VDC for five seconds, so I'd suggest that the armchair / pub scaremongers information is out of date at best.
The dealership I used to work at were happy to let the sales mongs loose with NOCO jump packs with no adverse effects, so on that basis alone, they're 'safe to use'.

 

[Ubique]

There probably is something to it. I remember in the 1990’s having a E30 BMW 325is and that had a whole procedure outlined in the owners manual on what you had to do if you wanted to jump start it. Headlights on etc to load it up as much as possible, supposedly to protect all the ecu’s it had in it.

Jump starting from a running vehicle is a different prospect entirely. Best advice is connect both vehicles for 15-20 mins, turn off engine after this time but leave connected, start casualty vehicle, turn on loads on casualty vehicle (lights are usesless on modern vehicles for loading the alternator, heated screens and blower fan / heated seats are high current loads), disconnect donor vehicle then reduce loads on casualty vehicle. Most batteries are sealed & vented well away from the terminals so connect / disconnect arcing shouldn't be an issue, it's still good practice to connect the ground last & disconnect first though - the idea is you avoid any arcing if you accidentally touch the positive to any bodywork.

 

[Matchless]

Main thing with jump starting with another vehicle or a jump pack is to make sure the dead vehicle is switched off before connecting jump leads or a pack to avoid the initial surge damaging ecu's. if using jump leads I always connect the leads with both vehicles off, then start the good vehicle and leave them connected for 5-10 mins before turning on / attempting to start the dead vehicle.

 

[Barking Mat]

I always attach the negative jump lead to the engine block not the battery. Positive yeah.

 

[Pigeon_Droppings2]

I've never had an issue with jump starting cars...maybe just been lucky!

I'm trying to follow the logic here...a car that wouldn't start got damaged by an attempted jump start. Would have thought it's more likely the problem was already there?

Reckon a simple caveat can be applied....I'm happy to try to jump start your car on the basis that any damage caused isn't my responsibility as some cars might not like it.

 

[Agrismith]

I've never had an issue with jump starting cars...maybe just been lucky!

I'm trying to follow the logic here...a car that wouldn't start got damaged by an attempted jump start. Would have thought it's more likely the problem was already there?

Reckon a simple caveat can be applied....I'm happy to try to jump start your car on the basis that and damage caused isn't my responsibility as some cars might not like it.

I think with the Renault/vauxhall at least, it is something built into the system to protect itself, either from hashed jump starting or maybe a theft immobiliser. It's definitely there as they fire straight up after following the procedure. But nothing is broken as they run fine afterwards. And it always happens after an attempt to jump start them.

 

[awemawson]

So that’s another vote for not running a modern vehicle then. I’ll stick with my 24 year old Landrover with no fancy electronics then thank you.

 

[Ubique]

So that’s another vote for not running a modern vehicle then. I’ll stick with my 24 year old Landrover with no fancy electronics then thank you.

In terms of vehicle technology, your circa 2000 MY Landrover is definitely 'Modern' - welcome to the current century! (and it will definitely have 'fancy' electronics )