Why Your Car May Not Start Even with a Jump (5 Checks You Can Do)

Having a good set of jumpers can give you peace of mind knowing that in the event that you are unable to start your car, your neighbor or partner can use their car battery to jump start yours.

Sometimes, your car can fail to start even with a good set of jumper cables and a known good battery. You turn the key in the car with the dead battery and probably all you are hear clicks or nothing at all

So, I have put together this guide to give you some ideas of likely causes (sometimes the solution is easier than you think) and what you can do in each case to get your car starting again.

Why Your Car May Fail to Start

If the car only clicks or cranks slowly or there is no click at all after connecting the jumper cables, then you should check if:

# 1. Jumper cables are wrongly connected. As simple as it may seem, confirm that the red jumper cable is connected to the positive terminals and the black cables to the negative terminal posts of the two batteries.

Some jumper cables have reverse polarity protection and will not work if connections are reversed.

# 2. You have loose or corroded battery contacts. You need to get solid good connections between the jumper cable clamps and the battery posts so that a high enough current to start the car can flow through.

Car Wont Start Clicking Noise - How...
Car Wont Start Clicking Noise - How To Fix It?

You may have to twist the jumper cables a little so that they bite the battery posts.

# 3. You have damaged or thin gauge jumper cables that are not able to handle the car’s starting current.

If the cables are undersized, particularly with cheaper cables or there is a break along the cable length then they cannot conduct a large enough current to start the car.

# 4. The car battery voltage is extremely low, has a fault – damaged or one or more cells are shorting.

Also, if the battery is damaged or deeply discharged, it will draw a lot of current leaving insufficient current available to start the car.

Is the dead battery warm or hot when you connect jumper wires to it?

If so, you may have an internal short-circuit that is drawing current from the good battery and starving the car of enough current to start.

Consider replacing the battery with a new one.

# 5. The car starter is faulty. If you confirm that the car is receiving power after connecting the jumper cables by, for example, checking that the sound system or the lights come on but when you try to start, there is no click and the car does not start, then there is a good chance that the car has a faulty starter.

Starters can fail as a result of repeated attempts to start the car or holding the ignition key in the START position for too long.

You may also be interested in the article: Car Starter Burn out, what you should know

Final Thoughts

If your car is not able to start even with jumper cables connected to a known good battery, start off by checking the seemingly obvious – make sure the jumper cable contracts are firm, cables should be thick enough to handle the high startup currents and should be connected the right way.

Then you can proceed to check if the battery is damaged and if the starter is in good condition.

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