Can a Bad Battery Cause Rough Idle?

It is pretty easy to know if your car is having an issue, from how it starts to how it runs, Which can be caused by several reasons. One of the most common parts that affect how a car runs is the battery. A bad car battery can cause the vehicle to run rough and affect the overall car performance. You can look out for signs to determine if your vehicle has a bad battery; read on to find out more.

Signs of a bad battery

There are many reasons a car can run rough, and it may not be the battery. However, the car shows any of the symptoms listed below, and then you’ve got a bad battery.

  • The electrical component of the car

The battery cranks the engine and supplies power to the car’s electrical components once the car is started. Some of these components include the headlight, the car radio, the dashboard light, the windows, etc. If the car can’t power up the radio or the car’s headlight is dim, it may be that the car battery is low and not supplying enough power to these components. The car should be taken to a mechanic for testing of the battery.

  • Clicking sound 

The car sends an electrical current to the starter when you turn on the ignition. The current is sent through the battery. A failing or low battery will cause a clicking sound due to the low current sent to the stater from the battery.

  • Pressing gas to start the car

For most cars to start, the driver only needs to press the brake and turn on the ignition. If you need to press the gas pedal before starting a car, this can indicate a bad battery.

  • Engine backfiring

A bad battery may lead to slower processing of fuel pump or improper openings or specific injectors, which may cause an engine to backfire.

  • Car check engine light 

Most of the car dashboard has an icon that looks like a battery. If the check engine light or the battery icon light is constantly blinking, it is a good sign that shows that the battery is low and may not be charging correctly and needs to be checked out.

  • Slow start

A lot of people are familiar with how fast their car starts. If the car seems to be starting slower than usual, it may be a battery problem. The battery supplies power to start the car, and if there is any sluggishness in starting, the battery needs to be checked out or possibly replaced.

an old car battery

What does rough Idle mean?

Idling is when the car is at rest: the engine is running, and the electrical component of the vehicle is working, but the transmission is not in gear, so the car is not in motion. Rough idle means the car is at rest, but the engine shakes and rumbles. You have a rough idle when the car idles unsteadily but drives smoothly. Some major pointers of rough idle include:

  • Shaking during idle
  • Inconsistent RPMs
  • Skipping sounds
  • Idling below 600 RPMs. 

If you have any of the listed symptoms, consult with a professional as soon as possible.

Can a bad battery cause rough Idle?

A bad car battery will not allow the car to run, but there is still the risk of stalling out. Without enough power from the battery, the alternator will try to power the engine, which causes extra stress in the car engine and cause it to stall out.

Can a bad battery cause Electrical problems?

There is a possibility a bad battery will not charge properly, which can affect the voltage regulators and the alternators. The loss of power and low voltage can cause intermittent electrical problems that occur at random times.

Can a bad battery have an affect engine performance?

A bad battery does not necessarily affect the performance of the engine. However, it can cause high temperature if the power supplied from the alternator to the engine has high amperage. This can cause engine overheating, which may damage the engine.

Can a bad battery affect acceleration?

A bad battery does not affect the car’s acceleration since the alternator takes up most of the electrical load as soon as the car starts. The bad battery can affect the start of the car but not the car’s acceleration.

Can a Bad car battery affect transmission?

Yes, a bad battery can cause the transmission to enter a fail-safe mode in the event of low battery voltage. This will eventually lock the transmission in the third gear and cause the loss of power to the car.

Can a bad car battery cause engine to shake?

Since the bad car battery may not supply enough power, the alternator tries to provide the needed energy for the engine to work. This extra load on the alternator causes the car engine to stall, creating a domino effect.

Can a loose battery terminal cause Rough idle?

Although it is slim, there is a possibility. The alternator will provide enough power for the electrical components and make the car run. The load, in turn, causes a lot of stress for the alternator, which can cause rough idle. Also, the voltage regulator or the alternator may be bad or going bad, increasing the possibility of a rough idle.

What else can cause a Rough Idle?

Although a bad battery causes rough idle, it isn’t the only cause of rough idle in a car. Some other causes of Rough Idle include dirty fuel injectors, clogged air filters, bad spark plugs, and various exhaust system issues.


Bad Car batteries are one of the leading causes of rough idle or car stalling a driver might face. Knowing the state of the car battery on time can help prevent the car from stalling and electrical problems. Once you notice any of the signs of a bad battery, it is best to consult with a professional mechanic to consult on the car battery.

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