What are the Symptoms of a Loose Battery Cable?

So what problems can a loose battery cable cause? A loose battery cable can cause excessive resistance to build up which can cause issues with the electrical system in your car.  You can have issues with your battery not charging all the way, problems starting your car, and dim headlights.

What Does Your Negative Battery Cable or Ground Strap Cable Do?

The negative battery cable attached to the battery in your car is there to provide a ground connection to the metal frame of your car.  With electronics, you need to have a positive and negative connection to complete the circuit.

You can connect something to the positive terminal of a battery but if there isn’t something connecting the two terminals together or a connection from the negative terminal to something metal you won’t be able to power your electronics.

That’s why it’s crucial for your negative battery cable to have a solid connection to the battery terminal and to the frame of your vehicle.

What are the Symptoms of a Loose Battery Cable?

1. Problems Starting Car

It doesn’t matter how many volts are stored in your car’s battery if it doesn’t have a strong ground connection you won’t be able to start your car.  Just because your car won’t start doesn’t mean that there is something wrong with the car battery.  If you’re currently having problems trying to get your engine running then you should inspect your battery cables to see if one of them is loose.  Sometimes the battery cables can become loose at the battery terminal connections and just need to be tightened up.

2. Low Voltage Car Battery

Another symptom of a loose battery cable is a low voltage car battery.  Battery cables need a strong connection to be able to transfer the electricity being generated from the car’s alternator to the car battery.  If your battery cables are loosely connected to the battery terminals all that electricity won’t be able to make it to the car battery.

3. Hot Ground Wire Cable

If you remember from science class electricity flows through a metal conductor due to an exchange between molecules and atoms.  As these atoms and molecules pass through the metal conductor some of them collide producing heat, this is called resistance.

As you should now know your negative battery cable or the ground wire connects to the frame of your car.  But if your negative battery cable is loosely connected to the battery terminals on your battery it can increase the resistance, thereby heating up your negative battery cable in the process.

4. Headlights Flicker

A loose battery cable can also contribute to having your headlights flicker or be dimmer than normal.  As you can imagine your headlights draw a lot of electricity to be able to illuminate the road ahead of you.  To be able to provide a steady flow of electricity to the headlights you need a strong and stable connection to the car’s battery.

If you have a loose battery cable it can allow your battery terminal connection to move around when driving over bumps or potholes which as you can imagine is not good for your headlights that need a constant flow of electricity to keep working.

How Do You Diagnose a Loose Battery Cable?

To diagnose a loose positive or negative battery cable you would want to open the hood or trunk (wherever the battery in your car is located) to be able to inspect the battery terminals.  Both the positive and negative battery cables should be connected securely to their respective battery terminal.

If you can easily move around the battery terminal connection or pull the battery cable off of the battery terminal then that’s an indicator that it’s not tightened enough.  You can tighten a loose battery cable in most cars by using a Phillips screwdriver or a socket designed to fit on the bolt at the battery terminal connection.

You may need battery post shims to allow your battery cables to connect securely to the battery terminals without leaving play in the connection.  To learn how to install battery post shims and to see if this could possibly be your problem check out the video below.

Can a Loose Battery Cable Drain a Car Battery?

A loose battery cable won’t typically drain a car battery but it can contribute to not allow the battery to charge properly.  Typically if your battery is draining after sitting for a while there is something drawing a charge from the battery while the car is off.  But there could also be a problem not allowing the car battery to be charged up all the way.

This sort of problem could be due to a loose battery cable but it could also mean that your alternator is going out.  To learn more about how an alternator works and determine if there is a problem with the alternator on your car check out my other article

-Link how to troubleshoot an alternator

How Do You Know If a Battery Cable Is Loose?

The easiest way to determine if your positive or negative battery cable is loose is by inspecting the connections of the battery cables on both battery terminals.  Both connections should not have any play in them or allow you to wiggle them around.  If you determine that one or more of your battery cable connections are loose then you would want to tighten them using the process outlined below.

How To Tighten a Loose Battery Cable?

The good news is that tightening a loose positive or negative battery cable is fairly easy and can be done by anyone that knows how to turn a wrench.  On most cars, there will be a nut attached to the battery terminal that needs to be turned to tighten up the connection.

You will need to tighten the battery cable connections using a socket, on my car I need a 10 mm socket to tighten or loosen my battery cables but your car could need a different size socket.

How Tight Do Battery Cables Need To Be?

Your battery cables need to be tight enough that you can’t move around the connection to the battery terminals.  If you can twist the battery terminal connection or move it around then it needs to be tightened.  You shouldn’t be able to move the end of the battery cable connection at all if it’s properly tightened to the battery terminals.

If you’ve ruled out problems with your battery and battery cables you may want to take a look at your alternator to see if it has a problem or is going bad.  But what are the signs of a bad alternator?

What Are the Signs of a Bad Alternator?

Your alternator is responsible for charging your battery so if it’s not functioning correctly your car won’t have enough voltage going to the battery to keep the battery charged.  This can lead to a whole slew of electrical problems.

Some signs or symptoms of a bad alternator are dim headlights, a check engine or “ALT” light on your dashboard, low voltage battery, or problems starting your car.  If you’d like to learn more about alternators and how to diagnose a faulty alternator check out my other article what are the symptoms of a bad alternator.

When Should You Replace Battery Cables?

You should replace your battery cables if they are visibly frayed or damaged, you should also replace your battery cables if they have signs of corrosion on them.  Corrosion can spread from the battery terminal connection throughout the battery cable increasing the resistance of the flow of electricity through the cable.

Another sign that you should replace your negative battery cable is that it is hot.  Hot battery cables are a sign that there is increased resistance in the battery cable and it needs to be replaced.  Under normal circumstances, your battery cables connected to your car battery should not be hot.  To learn more about the symptoms of a bad battery cable and when they should be replaced check out my other article.

How Much Does It Cost to Replace a Negative Battery Cable?

Usually, if you have a problem with one of your battery cables it’s going to be a problem with the negative battery cable. Negative battery cables are typically short enough to be connected to the frame of your car somewhere near the battery so they are relatively inexpensive.  You can expect to pay anywhere from $10-20 for a replacement negative battery cable.

Replacing the negative battery cable on your car should be relatively simple.  I’d recommend looking up the process on Youtube first to get a feel for how difficult the process should be.  From there you would need to determine if you want to attempt to replace the cable yourself or have a mechanic do it for you.

Why is my Negative Battery Cable Hot?

Having a hot negative battery cable is a sign that there is increased resistance in the battery cable.  This could mean that the battery cable is loose and needs to be tightened or it could indicate that there is something else causing the increased resistance like a corroded battery cable.

If you notice that your negative battery cable is hot to the touch (and it’s properly secured to the battery terminal) while your car is running or after shortly shutting it off that is a good sign that the battery cable is bad and needs to be replaced.

Can Car Battery Terminals Get Hot?

Car battery terminals will only get hot if one of the cables connected to them gets hot or there is a short somewhere in the circuit causing the cables to get hot.  Battery terminals and cables will only get hot if there is increased resistance in the cable causing the cable to heat up.

What is a Ground Strap or Ground Cable?

A ground strap or ground cable is essentially just another name for a negative battery cable.  In the UK most people refer to them as ground straps.