Car Starts with Jumper Cables only? (What to Do)

It can be so limiting and frustrating if each time you have to start your car you have to rely on a friendly driver and use a set of jumper cables, then open the hood to jump your car.

What causes a car to be jumped each time? Is this something you may be able to fix and if so how?

If these are the questions you’re looking to find answers to then read on. This post explains why your car may need to be jumped each time and what you can do to get it working reliably again.

Quick Answer

If your car needs to be jumped each time, it might be because the battery is damaged, low on charge, or even a case of battery cable terminals making weak contact.

Read on to find out how this contributes to the car’s inability to start without jumping, possible fixes, and what else could stop your car from starting without a jump.

5 Reasons Why a car may only Start with Jumper Cables

If the car is only able to start with jumper cables, it might be because:

#1. The car battery voltage is low or the battery is damaged. The car battery needs to have sufficient voltage and be able to hold charge under load to supply enough current to turn the engine over successfully.

Use a good quality voltmeter to measure the car battery voltage. A fully charged car battery has a resting voltage of 12.6-12.7 VDC. If the battery voltage is considerably low, about 12V or less then charge the battery.

If the battery is unable to hold charge, there might be a parasitic load drawing power from the battery or the battery is damaged.

It might be that the alternator is not charging properly. With the engine running, the voltage at the battery when the alternator is working properly should read in the range of 13.5 – 14.5 VDC.

Both the battery and alternator can be tested at a reputable auto parts store.

#2. The battery connections are loose, corroded, or damaged. Corroded battery terminals limit how much current can flow to the battery for charging or how much current the starter is able to draw from the battery when attempting to turn the car over.

Make sure the battery terminals are clear of any corrosion and are firmly connected. Are the battery cables including the ground cable connections still in good condition?

Beware that cables can appear to be in good condition when the inner strands are heavily corroded and only a few strands are left in the cable.

Conduct a voltage drop test to rule out any damaged cables.

What you need: Good quality multimeter, set to read DC volts.

How to test the Negative ground circuit for voltage drops

  • Start the car engine. Place the black probe of the multimeter on a known ground connection for the car such as a stud on the car’s metal chassis.
  • Next, connect the red meter probe to the battery post’s negative terminal. The voltage reading should not exceed 0.2V. If higher, confirm that the connections are clean and firm connections.
  • While keeping the black probe of the multimeter connected to the chassis, next, connect the red meter probe to the car’s engine block. The voltage reading should not exceed 0.2V. If higher, confirm that the connections are clean and firm connections.

If the voltage drop is higher than 0.2V with either the car chassis or engine block even after confirming the cable connections, then there is probably a broken or damaged cable connection that you need to identify and replace for a good ground connection.

If cables show signs of damage, replace them. If the alternator test fails, replace it too. Check if this clears the problem.

Related Questions

Why a Car can Start with Jumpers and then Die Down?

If your car (with a flat battery) cuts out shortly after a jump start, when the jumper cables have been removed, it is possible that there is a problem with the alternator or the battery not being able to power the car’s electrical system. You may be interested in this post Tips to Fix a Car engine that Stops after Jumping

Why a Car needs to be Jumped yet Battery is New?

There are several possible reasons why the car needs to be jumped each time yet the battery is new. Confirm that the battery is sufficiently charged (the car battery may still be new but because of a battery cable connection issue or a failing alternator may not be charging properly)

Also, check that the battery terminals are clean and firmly connect to the battery posts and that the battery wires are in good condition too.

Closing Thoughts

If your car only starts with jumpers only then at a minimum check and confirm that the battery is sufficiently charged and not damaged and that the battery cables are in good condition, clean, and firmly connected to the car battery tests.

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