Unable to jump start car with leads

millsy

My mother rang me the other day to jump start her car for her. She had left her lights on so I knew it was just a dead battery. I called over and followed the steps from the AA website using jump leads.

They state for the red lead:

" Use the red jump lead to connect the working battery’s positive (+) terminal to the flat battery’s positive (+) terminal. Never touch the ends of the red and black leads together as this could create sparks and cause vehicle damage"

For the black lead:

" Take the black jump lead and attach it to the negative (-) terminal on the working battery. Then attach the other end to an earthing point (unpainted metal on the engine block or chassis) well away from the flat battery and fuel system"

black jump lead.jpg

So following this advice I connected the black lead to the black battery terinal on my car, and the other end to a piece of metal in her car (see attached photo). I couldn't get her car started. I tried various locations in her car for the black lead and all caused a spark, before I settled on this location (which also sparked).

I've no idea why it was sparking nor why it wouldn't work. In the past I would have always connected the black lead on both ends to each battery, and it always worked, even though going by this guide (and others online) you shouldn't do this.

In the end I had to leave. One of the neighbours happened to pass as I left and offered to help. He brought his van over, and connected the black lead ends to the negative terminal on each battery (one to his black battery terminal and the other to my mother's black battery terminal), and he got it working.

Anyone know why I'm doing wrong and why it was sparking? And if the sparking is dangerous (they were only small sparks)?

10-10-20

If you got a spark then you made a circuit. The sparks are normal - things are powering up when you connect batteries.

I wonder was it your battery, and maybe the van was diesel so had a battery with a higher CCA value. Was his van running when jumping, and was your car?

o1s1n

You probably just didn't ground it properly, there could have been paint somewhere you didn't see or the metal you attached it to just wasn't a good ground.

I've jump started cars countless times and have always just gone to the negative terminal on the flat battery.

Rather than jump off another car I just use one of these now:

https://www.amazon.ie/NOCO-GB40-UltraSafe-Powerbank-6-0-Liter/dp/B015TKUPIC/ref%3Dsr_1_2?adgrpid=170118186410&dib=eyJ2IjoiMSJ9.pUStyv3xvMKlcxlQN1ITGi3mnS0d24QCg1awYAvpkAibUfFYoqMlp-MI5-DiMh0UrS34VF5m3ZtO4lyIXNI8vpcy0ce_lqYnrhJnquFoi8HoIGAD88m-P6yUSEi0RG62C9watEkJHMhbo4Edcc4v9rWQaskDZ3SUoMwNZwmy4DpN41beXz6G4M7ZiBVQOAL37DnrY2hXcvYNt5b1Q0uw7RzZULykkHATPRMHQo4QR67SNKPSqz4EyeaQz85J9DbN4DXx0DEXSvyaQJITvLyhdm3M9-BXKqFYAIbqE-q8FPU.jaWg67LP_OTuqk3gYyrOcfWqys8TlWm5iHvtP1PalEg&dib_tag=se&gad_source=1&hvadid=739737660656&hvdev=c&hvlocphy=9196675&hvnetw=g&hvqmt=e&hvrand=2176700288201911747&hvtargid=kwd-301239610504&hydadcr=27372_2423295&keywords=noco+battery+charger&qid=1761046721&sr=8-2

The NOCO instructions also have you just clamp black to the negative terminal

https://no.co/support/how-to-jump-start-using-gb40

10-10-20

I always wiggle the leads when I clamp them, helps to settle them into the metal and past any rust etc.

pjdarcy

The way your neighbour did it, is the way I've always done it too. Connect red terminal to red terminal and black terminal to black terminal.

Buffman

Sounds like you didn't get a good connection OP, while a spark indicates some connection it probably wasn't good enough to charge the dead battery enough to start.

Each vehicle owners manual will have the specific location to jump start that vehicle listed, just randomly connecting to some random parts based on generic AA advice isn't a great idea.

Personally I'd always go for the battery if it's easily accessible, but on the vehicles that's not easy, the manufacturers specified location always works.

millsy

Thanks for responses.

https://www.boards.ie/discussion/comment/123924293#Comment_123924293

My own car is a 2.0l petrol. Not sure what her car is. It's a Clio so that's likely 1.0l petrol too. No idea about the van; I'm guessing diesel. I would have thought any battery could charge up any battery enough to get it started.

Good to know that the sparks are normal.

https://www.boards.ie/discussion/comment/123924334#Comment_123924334

Good advice. Her car is fairly new so no rust (as can be seen in the attachment) but something to keep in mind in case there's any oil or dirt impacting the contact.

https://www.boards.ie/discussion/comment/123924360#Comment_123924360

I'll take a look at the manual (assuming she still has it) and see what point they specify. Worse case scenario, I'll connect directly to the black terminal (and hope the battery doesn't explode in my face :-) )

coylemj

I'll take a look at the manual (assuming she still has it) and see what point they specify. Worse case scenario, I'll connect directly to the black terminal (and hope the battery doesn't explode in my face :-) )

Connecting the black clip to a metal part of the car is fine but, in electrical terms, its the same as attaching the clip to the black (-) pole of the battery. Which is what your neighbour did.

In some cars, the battery can be in an awkward spot where the black terminal isn't accessible, it's really only in situations like that where you have to find an unpainted metal spot to use for the negative/black connection. Otherwise, if the four poles on the two batteries are all accessible, just go ahead and connect positive to positive and negative to negative.

Orban6

Make sure you have your engine running when trying to start the other car.