Can a Starter Drain a Battery? (Surprising Truth)

A battery can drain for various reasons, but can a starter also drain it?

A starter can drain a battery if it’s bad, especially if you keep starting your car several times with a bad starter. It draws high power (90-200A for 5-10 seconds) from the battery each time you start, even when faulty. If confirmed as bad, you should fix or replace the starter before it damages the battery.

It can also drain a battery when not starting the car; I will cover this more below.

Let’s see what a starter does, how it functions, what happens when it’s faulty, and how to tell if the starter is draining your battery.

What a Starter Does

A starter is an electric motor that helps the vehicle to start when starting the ignition.

Turning over an engine and cranking it requires a lot of effort. The starter helps rotate the internal combustion engine and initiate related operations. It includes letting air flow inside to allow fuel to combust.

Starters can be either electric, hydraulic, or pneumatic.

A Normal and Faulty Starter

Starting a car with a normally functioning starter only draws some charge while the engine starts.

The starter stops once the engine has started running, but the initial power draw is high. It usually draws between 90 and 200A for between 5 and 10 seconds, depending on the engine and starter motor sizes.

If you try starting a car several times for whatever reason, the total power draw is so significant that it can quickly flatten a weak battery.

A faulty starter that fails to stop working drains the battery even after the engine is switched off. That’s how a starter drains a battery. It’s usually the fault of the starter’s solenoid, but it could also be the starter relay or ignition switch getting stuck.

So there are four main reasons for a starter draining a battery:

  • High initial current draw
  • Faulty solenoid
  • Stuck starter relay
  • Faulty ignition switch

car starter motor solenoid
Car starter motor solenoid

How to Tell the Starter is Draining the Battery

Now that you know how a starter can drain a battery, you’ll want to watch it to ensure it always works properly.

Here are some things to check to know you must fix or replace the starter before it completely drains the battery:

Check 1: Accessories

Disconnect heavy and especially unnecessary accessories to see if the battery stops draining quickly. If it does, it might be the accessories, but if it doesn’t, then continue with further checks before suspecting the starter.

Check 2: Battery Connections

Both battery terminals must be clean, corrosion-free, and have good contact with the cable. Dirt, corrosion, and loose contacts can prevent the battery from charging properly.

Check 3: Battery

Monitor the battery’s voltage level and, if necessary, conduct a load test to see if it’s in good condition.

A bad starter is only one reason for a drained battery. The battery may be partially charged, weakening, or deteriorating due to age, overload, lack of maintenance, leakage, etc. A starter doesn’t normally drain a fully charged battery in good condition, despite the high current draw.

Check 4: Alternator

Ensure the alternator is charging the battery.


Video Reference

Cody the Car Guy

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About Alex Robertson

c3c9d43f1f0d14c4b73cb686f2c81c4e?s=90&d=mm&r=gCertifications: B.M.E.
Education: University Of Denver - Mechanical Engineering
Lives In: Denver Colorado

Hi, I’m Alex! I’m a co-founder, content strategist, and writer and a close friend of our co-owner, Sam Orlovsky. I received my Bachelor of Mechanical Engineering (B.M.E.) degree from Denver, where we studied together. My passion for technical and creative writing has led me to help Sam with this project.

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