Jump Starting A Car

[ed300zx]

most cars jump start in the same way but before we start it would be wise, if possible to check the owner's manual of your car as some things may vary.

WARNING

Before we start there are some warnings you should ad hear to, jump starting a car does sound simple but there are lots of things that can go wrong, such as;

Make sure the two batteries are rated to the same voltage.

The battery may explode (which will NOT end well for the person standing directly in front of the battery at the time, let alone the engine itself as the internals of the battery can disperse in the direction of the explosion) even though this rarely happens it is still a possible hazard if things aren't done correctly.

this leads us to our next precaution. make sure both batteries are well ventilated, for example make sure both bonnets are open all the way and in a ventilated surrounding area

make sure you use some good quality jumper leads. common sense will explain why

also be sure that the two cars are not in contact with each other as this would create a potentially hazardous electrical connection. If it does happen while the two batteries are connected, disconnect one of the clips again, but be extremely careful you only touch the clip’s insulation, and under no circumstances touch any parts of the car.

make sure that both cars are in park or neutral with the handbrake on (dont laugh, it happens )

make sure that your battery isnt dead and discharged. you can find out if it is by turning on your interior light. if it doesnt come on then your battery is dead and a new one is in order.

make sure that the ignition in both cars is off and no electrical items are turned on.

now that you have taken these precautions you are now ready jump start your car.

firstly connect one end of the positive lead (this lead will be red) to the battery that DOESNT need the charging. if the terminals on the battery are not colour coded or do not have a + or - symbol on it (a good battery will) then the positive terminal is usually the larger of the two terminals.

now connect the other side of the positive lead to the discharged battery.

now connect the negative (this will be the black lead) lead to the negative terminal on the battery that DOESNT need charging.

you have now got three (3) leads connected

NON DEAD BATTERY
positive (red)
negative (black)

ALMOST DEAD BATTERY
positive (red)

this leaves one black lead. now with this final lead, connect it to somewhere in the engine bay of the car with the dying battery, that is not painted, in order to earth it. make sure none of the leads come in contact with each other at this time as this may cause a short circuit. DO NOT CONNECT THE LAST LEAD TO THE LAST REMAINING TERMINAL

now it is time to start the car that DOESNT need the charging. let the car idle for a few minutes.

now start the car with the flat battery. allow both cars to idle for a few minutes until it starts to idle smoothly.

once this has happened it is time to disconnect the leads. this must be done in the reverse order that the leads were connected. do this with both cars still idling. so;

firstly disconnect the black lead that was earthed on part of the car with the dead battery.

secondly disconnect the black lead that is connected to the negative terminal on the car that was doing the jumping.

thirdly disconnect the red lead that is connected to the positive terminal on the once dying battery.

fourthly and finality disconnect the red lead that is connected to the positive terminal on the car that was doing the jumping.

the car that was doing the jumping is now fine to switch off.

the car that was jumped should be taken for a 15-20 minute drive to ensure that the battery gets a good charge.

and that is all. good luck

[dan300zx]

i was told about the earthing of the lead way back in my days of high school automotive workshop, long before i ever owned a car.

but the rac dudes told me it makes no difference if you earth it or connect it directly to the other negative terminal and i have jump started my car this way on their advice..

[ed300zx]

Originally Posted by dan300zx

i was told about the earthing of the lead way back in my days of high school automotive workshop, long before i ever owned a car.

but the rac dudes told me it makes no difference if you earth it or connect it directly to the other negative terminal and i have jump started my car this way on their advice..

yeah i used to always just put it back onto the remaining negative terminal but asked around and it seems more people did it the earthing way so i just wrote that one instead

[Cpt. Ash]

much of a muchness I thinks....

Niall might be able to clarify this, but upping the revs of the car used for trying to start the other has no effect. Apparently a change in the design/output of modern alternators contributes to this.

Another thing aswell is to buy a set of good leads, preferrably ones with a safety cutout. I have been victim of touching leads and these ones will prevent them from shorting out something.

[Niall]

My contribution.

The reason they say not to connect the earth lead to the terminal on the battery is that dischargd batteries release a potentially explosive gas and the spark whn you connect the lead could set it off, connecting the lead away from the battery removes this danger.

The other thing i would suggest is to leave the leads on for a good 5 mins if jumping from a running car as a large voltage spike can occur when removing them which can damage electronics.

Ash is right that most modern cars have very effective voltage regulators and will not increase the charge voltage as you rev them.

I would also suggest not using one of those high voltage booster pack things as i have seen them fry a few control modules in very expensive cars!

[DattLefs73]

Hi Lem.
I usually post on here when were going out. I dont think Ill have many pointers for you Ive just about mastered the upwind thing and as I have said just starting to jump.
What board are you using? Im on a 139 SX which poves the chop Thank god Your welcome to have a shot on it.
Be good to meet up though...Its just a matter of when