Why your Car may not Start and has no Power (even with Jumper cables connected) (+Fixes)

Your car may have a dead or drained car battery for a number of reasons – age, poor quality or it’s just that they may have suffered damage from prolonged deep discharge and other reasons.

When your car has a dead battery, the solution that is usually recommended is to jumpstart it with a set of jumper cables and for good reasons, it is low cost and effective!

But what if your car still cannot start when you turn the ignition to the “START” position?

What if it shows no signs of power – no radio, interior or dashboards lights with the key turned and the jumper cables properly connected?

What do you do?

Read on for suggestions of what you can do if your car is not able to start even with the jumper cables connected and also what may be stopping it from starting.

Quick answer. If your car is not able to start and has no lights even after connecting jumper wires then its electrical system is not receiving power from the battery.

Assuming that its battery is dead and you’re relying on another car (with a charged battery) to charge it then as a first step:

#1. Check and confirm that the jumper cables are intact and not damaged along their length.

You may have to swivel then so that they cut into the battery post for a good firm connection.

#2. Also, inspect and clean the battery posts of the dead battery and remove the greenish-blue powder that may have built upon the battery cable clamps and posts.

Make sure that the battery posts are firmly connected.

Read on for other likely causes of why the car may have no power at all.

4 Simple Checks you Can Do if Car has no Power (with Jumpers Connected)

#1. Inspect the jumper cables along their length to confirm that there is no damage and make sure they are firmly connected to the battery posts.

On the car with the flat battery, confirm that the black jumper cable is connected to the exposed metal of the car chassis.

#2. Make sure that the battery posts and battery clamps on either of the car batteries are clean, have no corrosion, and firmly connect to the battery posts

#3. Confirm the battery ground connection on the dead car’s battery is firm and makes clean contact.

#4. Confirm the drained battery is not shorting. You may have to take it out, charge it and have it load tested too.

Why your Car may not have Power even with Jumper cables connected

#1. It has Loose or corroded car battery terminals. If any of the battery cables is loosely fixed or corrosion has built up around the posts or cable clamps, then current flow will be restricted because of the high resistance created, and the car will have no power at all.

Fix. Clean the powdery residue off the connecting wires by pouring baking soda mixture over the terminals and brushing it off.

Finally, apply dielectric grease or vaseline on the clean battery terminals to protect the metal from fumes before reconnecting the wires back to the battery terminals.

#2. The car has a loose or broken battery ground connection. If the battery ground connection is damaged then your car will not receive power at all.

You can also measure the voltage with the positive probe of a good quality meter connected to the battery positive and the negative, first at the negative battery post and then at the engine block.

The voltage should be the same. A difference in the voltage indicates a break in the ground cable.

Fix. Replace the damaged cable.

#3. The car battery has an internal short. If the car battery is shorting, then it will starve the rest of the car’s electrical systems of electrical power even with the jumper cables properly connected.

You’ll likely see a large spark when the last battery connection is made if the drained battery is shorting – a sign that there is a high power draw from the charged battery.

Another sign to look out for is the temperature of the battery. A battery with an internal short will become hot when connected to a charging source like a charged battery.

Fix. Have the battery tested at an auto repair shop and replace it with a new one if confirmed

#4. Damaged jumper wires. Though not common with good quality jumpers, a break in the jumper wires (under the insulation) stops the flow of power to the car with a dead battery.

Fix. Replace the damaged cables with a working set or you can use a battery-based jumpstart box.

You may also be interested in this post: Can jumper cables go bad?

Final Thoughts

If you connect a set of jumper wires to a car with a drained battery and there is no sign of power at all when you turn the ignition on, then you should check the following: broken jumper cables, jumper cables not firmly connecting to the battery posts, corrosion on the battery posts, bad car ground or a shorting battery.

Any of the above can stop your car from receiving electrical power.

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