Can A Bad Starter Drain a Battery?

There are many components of the car responsible for the car to start. One of the essential parts is the car starter. A lousy starter can affect the car ignition system, which may not allow the car to start. Since the battery is one of the components that helps the car start, you may be wondering if a bad starter can drain the car battery. The article will help you better understand the role of the starter and its effect on the car.

What is a car starter?

A car starter comprises an electric motor and a Solenoid that aids in the correct start-up of a vehicle. The starter aids in the rotation of the internal combustion engine and commences the start-up procedures for a vehicle. The car starter can best be understood by knowing the components that made it up. The components are:

  • Armature: This is an electromagnet attached to the driving shaft and bearings for support. It has a soft iron core that is laminated and wrapped with multiple conducting loops or windings.
  • Commutator: A portion of the shaft at the rear on which the brushes conduct electricity. It is made of two plates connected to the axle of the armature. The plates provide the connections for the electromagnet’s coil.
  • Brushes: they run along the commutator in the back of the casing and help to conduct electricity.
  • The solenoid acts as a switch to complete the electrical circuit and connects the starter motor to the battery. It consists of two wire coils wrapped around a moveable core.
  • Plunger: this works in contact with the battery and Solenoid and helps to engage the moving pinion gear.
  • Lever Fork: it is connected to the plunger and mimics the acts of the plunger. If the plunger moves forward, so does the lever fork. It helps activate the pinion.
  • Pinion: this is a combination of gear and springs. The starter is activated, the gear is stretched into the gearbox case and connected with the flywheel. This helps start the combustion process by spinning the engine.
  • Field Coils: The starter field coils are held in place by screws in the housing. This can be made up of two to four field coils linked together in a sequence. The coils are converted to an electromagnet by the battery, which then turns the armature.
car starter

How a car starter works

When you turn the key to the on position, a current passes through the starter motor, activating the electromagnet in the body. By activating the electromagnet in the starter, an electric trigger in the solenoid component pushes forward a plunger, which pulls out the pinion gear. The plunger also makes touch with the electric motor component, which contains an electromagnetically rotating armature. After that, the rotation output is sent to the pinion gear, which engages with the flywheel. This movement gives the engine rotational momentum to spin over. Electromagnetic forces propel the plunger, rotate the armature inside the motor, and lock the pinion gear with the flywheel thanks to many bearings and gears within the Solenoid and electric motor parts. The starter disengages, and the electromagnet ceases as the engine spins over. The rod reverses back into the starter, preventing damage to the pinion gear by removing it from contact with the flywheel. If the pinion gear stayed in touch with the flywheel, the engine would spin the starter extremely fast, thereby damaging it.

Can a bad starter Drain a battery?

The simple answer is, Yes, a bad starter can drain a battery. When starting a car, the starter uses a lot of battery energy. A bad starter’s repeated attempt to start a car can drain the battery entirely as it draws a lot of power. This is one of the leading causes people might change their batteries periodically. A lousy starter can be difficult to notice as it shares symptoms with a drained battery and a faulty alternator. A bad Solenoid can also cause a battery drain as it is part of the starter.

How to Know if you have a bad starter

You can lookout for a few signs if you have a bad starter, as this can prevent it from completely draining the battery. Some of these symptoms include:

  • Strange noise: pay special care to the sound you hear when you are about to start your car. If there are unseal whirring and grinding noises when you turn the key, it is an indication that the starter may be faulty. Also, if you hear the sound but the engine refuses to crank over, it is most like the starter.
  • Light coming on but car not starting: if after turning the vehicle, the dashboard light and the car headlight come entirely on, but the engine does not start, it is most likely that the starter is not working. However, if the headlights are dim, the battery may be faulty. Call a professional for help to be sure.
  • The engine does not start: the most apparent reason that the starter may be faulty is if, for whatever reason, no matter how many times you try, the engine is not coming on. The starter helps power the engine before it can start, so if the engine is not coming on, the starter may be faulty.
  • Smoke or strange smell: if you notice a peculiar smell or smoke from the engine every time you try to start the car, the starter may be responsible. However, other causes can cause a strange smell or smoke, so it is better to consult a professional on time before more damage is done to the car.
  • Battery test: open the car hood and remove the battery terminals. Reconnect the terminals starting with the negative. Then turn on the headlight and cabin light. If it is dim, it is the battery; otherwise, it is the faulty starter.

Can a bad starter drain a battery overnight?

Ideally, it is not possible as the starter only engages the battery when the car is about to start. Even though the possibilities of something like this happening are incredibly remote, it is nonetheless possible. A defective starter motor can drain your car’s battery over time. As a result, even though the engine was turned off, the battery would be dead in the morning.

Things that may drain a battery

One of the things that drains a battery is the starter, but it isn’t the only car component that causes a drain. Some of the other things include:

  • Leaving headlight on
  • Battery connection lost or corroded
  • The temperature 
  • The alternator is not working
  • An old battery that won’t hold a charge

Tips to extend the car starter’s life.

The only solution to a bad starter is to replace it, but there are ways you can ensure the starter works for a long time. Here are some tips to maintaining your car starter:

  • Tighten the mounting bolts: the mounting bolts help keep the starter in place to prevent movement. Check the bolts periodically and make sure they are tight. Loosened bolts can cause the starter to shift and cause damage.
  • Clean the connector: Connecting rods and wires are essential in ensuring that the circuit is completed when starting a car. Clean off dirt, grimes, and corrosion as soon as you notice them. They can quickly reduce the current strength and weaken the starter.
  • Clean the Solenoid: the Solenoid helps connect the battery and the starter. Dirt accumulation debris may reduce the efficiency of the Solenoid, which can cause issues for the starter. It is best to regularly check the battery, terminals, starter, and engine and clean them out as best as you can.


A car starter is an essential part of operating a car as it is needed to start the vehicle. However, a lousy car starter can drain a battery due to the amount of power it draws from the battery when the car is about to start. Although other factors may cause battery drain, the symptoms of a bad starter can easily be looked out for and help prevent further damage to the starter and the battery. Car owners can help prevent damage to the car starter by closely monitoring the components involved in starting the car. However, if you suspect that your vehicle has a bad starter, it is advisable to seek professional help as soon as you can.

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