My car doesn't start even after a jump start please help :(


I purchased some jump leads which are significantly better than the previous pair. Now when I tried to get the car jump started I hear the engine turning a few times much stronger than before as if the car is about to start but it just doesn't start up. I tried with two different cars and the same thing happened. Is it still possible that the problem is with the battery or is the problem definitely elsewhere?
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...but the quality of the leads wont stop the car starting.. they will get hot and eventually melt and burn but they should still start the car unless there is another problem somewhere else.

i admit, that the hotter they get the more resistance in the conductors, but ive had insulation melting and dripping off a set of leads but the car always started!

You can jump start a car with the dead battery completely removed - just join the battery leads directly to the jump leads, and onto the good battery. It still works, so the suspect battery wont be preventing the car starting when jumping. It just wont charge / hold any charge if the battery is completely knackered.
you will get a voltage drop in the cables, especially if they are thin.

I have a huge set of jump leads in 25mm copper cable. It would be rated at 100Amps for a house supply to the meter. My car battery is rated at 420 Cold Cranking Amps. So I bet a weedier set of leads would not be up to the job.
yes your right, because the resistance will increase, but as said ive had the insulation melting and burning off the conductors whilst jumping but its always started the car even if its destroyed the leads!
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As already been said, you won't jump start a car with a flat battery with cheap jump leads.

You need 25mm2 to do this, ESP with a diesel.

Also if the battery is duff it will be sapping the amps while it's being jumped, so it won't get to the starter motor.

If your battery went from 11v to nothing in a few days, it's no good to anyone and your wasting your time jumping it.
The jump leads I bought from B&Q today are 40mm2 so I thought that should be big enough to do the trick.
they certainly should be, unless the old battery is sucking the power out of them.

Are they copper or aluminium?
It says copper clad aluminium cables with PVC insulation. The battery is relatively new. I bought it from ATS about 6 months ago.
I did buy a battery charger but when I connected it to the battery the charging light didn't come on. Not sure if it is because mine is a calcium battery or the battery is dead but ATS told me battery seemed good and it was just low on voltage so I'm not sure what the problem is.
I have had massive problems with jump leads in the past....

Basically if you need a pair you can rely on don't pay less than £45...

Make sure you're leaving them connected for a while to pass enough charge before you go trying to start the car.

For the sake of £40 I would just buy a new battery to be honest?
P.S after 6 months no battery should be "low on voltage" unless something is draining it.
I've had instances in the past wher i've bought a brand new one off the shelf and it's been dead.
P.S after 6 months no battery should be "low on voltage" unless something is draining it.
I've had instances in the past wher i've bought a brand new one off the shelf and it's been dead.
Exactly. A battery that's "low on voltage" is either flat, and needs charging, or it's duff, and needs changing. If your's won't accept a charge (and assuming the charger is OK) then it must be duff. If it's six months old take it back to ATS and ask them to either charge it up or replace it. Either way you'll eliminate the battery as a problem.
Just to add my 2pence worth.. have you checked the alternator and leads?
the reason i ask is that if you've got a replacement battery, the previous battery might have been suffering from not being charged by the alternator or by being drained in the same way.

although, as others say a duff battery if charger is working it won't charge.
Hi, you could have a thing called parasitic draw make sure everything is turned off and all door lights are going out when you leave the car. Also a car needs 12.5 voltes to start the engine. It sounds like a bad battery. I would start there not least because it's the cheapest and easiest thing to fix!
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