How do I jump start a car?

Random · 14-04-2009 10:31PM #1

Can someone just tell me if I have this right?

- put the 2 cars bonnet to bonnet or side by side.
- Start the engine on the car that you're using for the jump start.
- whack the +/- on one battery and onto the +/- on the other battery.
- rev the engine on the car being jump started.
- disconnect cables and off you go.

Simple as this?

What happens if I put the +/- on the wrong spots on the battery or something?

Thanks

SAABMAN · 14-04-2009 10:40PM

Not really the way to do it.
+ to + OK
but - on donor car to an earthed point on the car to be started.
Not all cars are safe to jump start and can suffer computer problems related to the power surge when the second car starts.

Masada · 14-04-2009 11:21PM

best thing to do it attach the black cable from chassis to chassis on both cars, and the red to positive pole on both. leave it for a few mins to get some power into the dead battery and it should start no probs, you dont need to rev the engine.

Dartz · 14-04-2009 11:25PM

Alternate method, provided you have a second strong friend and a manual gearbox.

Turn on ignition. Put car in 1st. Push in clutch. Have friend push car to speed. Dump clutch and hope it fires. Unless the batteries absolutely bolloxed, you should at least have fuel and ignition available.

Random · 14-04-2009 11:27PM

I should have the engine on in the car that is "giving" the jump start right?

congo_90 · 14-04-2009 11:27PM

positive to dead battery
positive to good car.
Start good car and let run
connect negatives up
give her a min
start em up and disconnect in reverse order

I do this all the time as I don't drive my car much and regularly have to jump her. I'm sure there's other ways and people worried about damaging the ECU etc but no harm has ever come to my car or the donar

DONT let the cars touch or you touch both at the same time! you will get a nasty shock!

Put em on wrong and the car wont start but in fairness most cables are colour coded and labelled RED (+) and BLACK (-) and on some new cars the positive cable has a red cover over it.

SAABMAN · 14-04-2009 11:28PM

Dartz wrote: »

Alternate method, provided you have a second strong friend and a manual gearbox.

Turn on ignition. Put car in 1st. Push in clutch. Have friend push car to speed. Dump clutch and hope it fires. Unless the batteries absolutely bolloxed, you should at least have fuel and ignition available.

2nd gear and a spare cat.

Masada · 14-04-2009 11:29PM

If theres no power at all then some cars wont start like that because the ECU isnt getting anything from the key to let it start, it can also be done by towing.,

Edit, post directed at Dartz.

Random · 14-04-2009 11:31PM

Another thing as well - what damage can be done to my car by letting someone jump start theirs off it? (in a car park for example).

congo_90 · 14-04-2009 11:54PM

Random,
As i said in mine. I've never damaged either cars ever. You've no worries just make sure your engine or whoever's car is the good one has it's engine running or else you may find yourself with 2 dead cars lol. which isn't fun. never happened to me. But it could.

Random · 14-04-2009 11:57PM

Should I have the engine running BEFORE connecting the leads to the battery?

Darragh29 · 14-04-2009 11:58PM

Random wrote: »

What happens if I put the +/- on the wrong spots on the battery or something?

You create a complete mess, you can even start a fire or cause the battery in either or both cars to explode due to rapid discharge, as well as melting the wiring in the car or blowing fuses.

If you even think you are going to do this, get someone else to do it.

congo_90 · 15-04-2009 12:00AM

It's optional. I rather it. but definately have the good car running BEFORE attempting to start the dead battery if ya get me.
Is your car dead or ya just curious? if ya don't mind me asking.

Random · 15-04-2009 12:05AM

congo_90 wrote: »

It's optional. I rather it. but definately have the good car running BEFORE attempting to start the dead battery if ya get me.
Is your car dead or ya just curious? if ya don't mind me asking.

I came out of a shopping centre the last day. Lashing rain. Some poor chaps car wasn't starting and he'd ran into the SC to get some jump leads. He can out and asked if I'd help him out.

I'm not a complete idiot but having never done it before I just opened the bonnet and told him to sort it out.

He hooked the leads up. Started his car. Unhooked the leads and off we both went.

I never started my car the whole time, nor did he tell me to.

Yah, maybe I'm an idiot for letting some near my engine without knowing what's going on fully but what can I say ....

No problems with my car after but just trying to broaden my knowledge

Masada · 15-04-2009 12:14AM

you'll be grand, it can cause problems sometimes if you start the car while connected to the dead car, my 2004 civic will throw an airbag light if connected to someones car without the engine running.

Rowley Birkin QC · 15-04-2009 12:31AM

I fcuking hate jump starting cars or tractors, anything to do with electricity really.

Spent two recent summers driving tractors on motorway construction sites and always played dumb when it came to refueling at a bowser that didn't have a working battery.

Esel · 15-04-2009 02:10AM

Best advice is never connect negative terminal to negative terminal! Always connect negative to an earth point away from the battery on the dead car.

BrianD3 · 15-04-2009 08:48AM

bigkev49 wrote: »

I fcuking hate jump starting cars or tractors, anything to do with electricity really.

Spent two recent summers driving tractors on motorway construction sites and always played dumb when it came to refueling at a bowser that didn't have a working battery.

I'm also wary of jump starting. If I have a flat battery in one of our cars I will generally take it out of the car and put it on a mains charger. Or else just disconnect it and bring the charger to the car if the car is within about 50 metres of a mains socket. Obviously those are not always practical solutions to a flat battery.

Also, if doing anything with car batteries you really should wear eye protection. If the battery explodes and sprays sulphuric acid everywhere you'll be glad you did :eek:

david · 15-04-2009 09:24AM

esel wrote: »

Best advice is never connect negative terminal to negative terminal! Always connect negative to an earth point away from the battery on the dead car.

Any particular reason for this, I've always done this but never knew why really...

Esel · 17-04-2009 02:11AM

david wrote: »

Any particular reason for this, I've always done this but never knew why really...

Something to do with sparks and possible battery explosion.... :eek:

yuloni · 17-04-2009 02:25AM

This post has been deleted.

Richie15 · 17-04-2009 05:42AM

Says on the instructions, red lead to dead +ve, other end of red to healthy +ve, black to healthy -ve, other end to dead engine block. Then start the dead car and remove them in the reverse order.

AFAIK, if the dead car's alternator's ok you don't need to start the healthy car and even if it's not, the amount of time taken to figure out you have a problem beyond a dead battery is usually not enough to run it down. If you're push-starting it, put it in second and press the clutch. When you've built up a bit of momentum, let it off as though you were changing gear and, presto (again, as long as your alternator's ok).

My first car needed a new batt and alt, second just needed a new batt and I learned my lesson, third died of natural causes. :P

Fiona500 · 17-04-2009 06:00AM

Random wrote: »

Should I have the engine running BEFORE connecting the leads to the battery?

I am not an expert, but I would be afraid getting a shock by doing that. I have jumped batteries hundreds of times and have never attached the cables when the engine is running.

Tip: While the leads are attached to one of the batteries NEVER let the metal on the opposite leads touch. They will spark off each other and could set you on fire, or worse.

Pkiernan · 17-04-2009 07:12AM

As a few people have posted above, the SAFEST way is:

Positive to Positive.
Negative of good car battery to grounding point in bad car chassis.

The reason for this is, if the cables are going to spark, it will most likely happen when connecting the final negative cable. If there is a spark at a bad battery terminal, and that battery is leaking Hydrogen gas, there will be an explosion.

Jip · 17-04-2009 09:09AM

Pkiernan wrote: »

Negative of good car battery to grounding point in bad car chassis.

Yip, not like as many people say - to - of each battery.

+ of dead battery to + of good battery,
- of good battery to a metal part of the dead car, I usually stick it to the body work inside the engine bay somewhere

and work backwards in removing them.

mickdw · 17-04-2009 09:24AM

I agree with the + to + and - to engine block of flat car. However, once on a building site we had a flat forklift. An auto electrician was on site so he pulled his van over to start it. He connected up as stated above with his van started. He would not allow us to then start the forklift. He insisted that he leave the van there for about 20 mins to charge the dead battery. He then disconnected and started the forklift with its own recharged battery. This guy reconditions starter motors/alternators for a living and he said damage to alternator is very likely with the typical method of starting while still connected.

Richie15 · 17-04-2009 04:46PM

mickdw wrote: »

He insisted that he leave the van there for about 20 mins to charge the dead battery. He then disconnected and started the forklift with its own recharged battery.

My sister told me that once and I didn't believe her. In my defense, she doesn't recondition starter motors for a living though. :P

groupb · 17-04-2009 05:07PM

Dartz wrote: »

Alternate method, provided you have a second strong friend and a manual gearbox.

Turn on ignition. Put car in 1st. Push in clutch. Have friend push car to speed. Dump clutch and hope it fires. Unless the batteries absolutely bolloxed, you should at least have fuel and ignition available.

New cat needed after this method. It used to be fine years ago but now its a no no. Same goes for tow starting.

Richie15 · 17-04-2009 06:25PM

groupb wrote: »

New cat needed after this method. It used to be fine years ago but now its a no no. Same goes for tow starting.

As in catalytic convertor? I've done that a few times with no problem (as far as I knew). Older cars, does that make a difference?

Carawaystick · 17-04-2009 07:29PM

first time the battery died in a 94 corolla I push started it every morning for 10 days till payday came to get a new battery. passed 4 nct's since and I'm hoping to get another 1500 miles to roll over 200k.... no cat issue.

So the negative lead just connects to the engine to avoid a spark setting off the H2?

How do I jump start a car?

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