Can You Jumpstart a Car with a Bad Alternator? (Explained)

Can You Jumpstart a Car with a Bad Alternator

Alternators are designed to last long, between 7-10 years provided nothing else is wrong in the engine but it is not uncommon to see them go bad faster.

If the alternator goes bad and can’t recharge the battery, the last resort to getting the battery charged and the car running may be to jumpstart it. This leads us to the question, can you jumpstart a car with a bad alternator?

You can jumpstart a car with a bad alternator and the engine will run fine provided the battery is in good condition. However, it is only a matter of time before the battery drains and the car stop running. You need a good alternator to charge the battery while the car is in use.

What is an Alternator?

An alternator is an electronic device in a car’s engine responsible for powering the battery and other electrical through the conversion of mechanical energy to electrical energy.

Alternators are usually most active when the car is running in that it works actively all things being equal to ensure that the battery does not run. A car battery and alternator can be said to be two pieces in a pod.

Although a battery can run without an alternator, it definitely won’t last long. Without an alternator to recharge it a battery can last a maximum of 2 hours.

With proper maintenance, an alternator can last between 6-9 years, however, if something were to go wrong with it, it will give signs.

As part of maintaining the alternator, you can test the state of the charging system to know whether it is still working or weak.

In replacing a bad or worn alternator, you can either buy a new one aftermarket or have it rebuilt. Rebuilding a bad alternator is cheaper than getting a new one.

What Does it Mean to Jumpstart a Car?

Jumpstarting a car means starting the car by temporarily using another source of current or electrical power. This is usually done when the car’s battery doesn’t have enough power to start the car as it ought.

When jump-starting a car, you would need a ‘Jumper Cable’, which is used in the transmission of current from other sources into the car.

Jump starting is a process of boosting a car’s battery from an external power source long enough for the battery to recharge and start the engine.

Once the battery has regained some electrical power, it shouldn’t be hard for it to continue charging from there provided the charging system is working well.

Can You Jumpstart a Car with a Bad Alternator?

Yes, you can jumpstart a car with a bad alternator. Jumpstarting a car is a short-term way to get the engine up and running and can be done even when the alternator is bad or faulty.

The alternator is solely responsible for recharging a car’s battery when it’s running and also provides power for the proper functioning of other electrical components of a car like the; headlights, interior lights, etc.

The car will run fine if you jump start with the alternator bad provided the battery is in good condition. However, irrespective of whether the battery is in a good condition or not, jump-starting won’t make the car run for long unlike having the alternator in place to keep recharging it.

With a bad alternator, the car is running solely with the battery and this won’t keep it running for a long period. Jump starting is recommended when you are probably going on a short drive.

Although it is possible to jumpstart a car with a bad alternator, there are certain dangers attributed to doing so, especially in newer cars.

How to Jumpstart a Car with a Bad Alternator

There is a safe way to jumpstart a car with a bad alternator, the timing, when and how to remove clamps, etc. The procedure for jumpstarting a car with a bad alternator is the same with a car with a good alternator.

Here are some procedures to consider in jumpstarting with a bad alternator;

First thing First: Before Jump starting

  • Be sure both cars are not in contact
  • Remove ignition keys from both cars
  • Locate the positive and negative wires on the battery
  • The clamp should not touch at all

Attaching the Clamps

  • A red clamp should be connected to the dead battery
  • While you connect the other Red clamp to the good battery
  • A black clamp should be attached to the good battery
  • The other black clamp should be grounded to bare metal e.g. bolt head nut etc.

Start the Engine

  • You should start the engine with the good battery
  • Run the engine for 3 minutes at 2000rpm as a minimum
  • Let the engine run for a minimum of 15 minutes at 2000rpm if you are driving with a bad alternator
  • You may need to run for much longer if the engine is colder
  • Crank the car with the bad alternator, if it isn’t working, try another 3 minutes

Remove the Clamps

  • First, remove the black clamp from the dead battery
  • The red clamp on the dead battery should be removed next
  • Next, remove the red clamp on the good battery
  • Lastly, have the black clamp on the black battery removed

The Alternator Should be Fixed

Just because the engine is running doesn’t mean you should delay fixing or replacing the alternator. The engine’s continuous running depends on your fixing the alternator.

Jumpstarting a car will not damage the alternator, but you need to have the alternator fixed or replaced in no time.

Pros of Jumpstarting a Car with a Bad Alternator

Jumpstarting a car may be all that a car needs to get it up and running till the real problem of a bad alternator is fixed. Alternators go bad all the time and should be fixed as soon as possible in order to keep the car on the road.

There are some benefits and advantages of jumpstarting a car with a bad alternator. These are;

  • You can Run a Few Errands: Jumpstarting a car even with its alternator bad affords you the opportunity to run a few errands or as long as the recharged battery can go. The number of errands you can go on will depend on the battery’s condition and provided other components of the car are not using the battery.
  • The Car isn’t Completely Useless: By jumpstarting the car, the car won’t be idle with no use and waiting for when you come around to fixing or replacing the bad alternator.
  • It’s a Way of Knowing the True Condition of your Battery: Jumpstarting a car with a bad alternator means the car relies on the power in the battery to run. If the battery lasts a little longer then it’s in a good condition but if it doesn’t, you know a change is in order.


Jumpstarting with a bad alternator may not be the best option because of some of the dangers that come with it, but If you have no choice but to jumpstart your car, do it the safe way.