Why Do Battery Cables Get Hot? (Here’s What To Do)

When operating a vehicle, you will want to make sure you have working battery cables. Battery cables transport energy between the battery and starting systems. Without them, you cannot start your car.

Each time you use your vehicle, the battery cables handle large quantities of electricity. By checking them frequently, you can prevent any issues with them. However, many of us fail to check the battery cables until it’s too late. That’s when you might experience your battery cables getting hot.

Why do battery cables get hot? Here are some key points that I’ll cover in this article:

  • Positive and negative battery cables
  • Glowing and melting battery terminals
  • Caring for a hot battery cable
  • Signs of damage

Keep reading until the end to learn all you need about hot battery cables.

Car battery connected to cables

Why Are My Positive and Negative Battery Cables Getting Hot?

There are several reasons for a battery cable to get hot. It may have corrosion, a loose connection, or an issue with the starter or engine.

Corrosion

Battery cables typically have copper, lead, brass, or bronze compositions. 

Copper is an excellent material choice because of its high electrical conductivity and corrosion resistance. However, they are pricey to manufacture and challenging to find.

Lead cables are the most common due to their strength and low cost. Nevertheless, they have relatively low current conductivity. Furthermore, lead is moderately susceptible to corrosion when exposed to oxygen.

Brass cables have high corrosion resistance, but you need to install them carefully to avoid breaking them during tightening. Bronze has higher corrosion resistance, strength, and durability than brass.

The electric vehicle cable market has an expected compound annual growth rate of 25.4% from 2021-2027. These developments could lead to new materials for cables that may prove better than the existing options.

Many vehicles have lead battery cables, which are likely to develop corrosion that creates resistance to the flow of current. 

When you increase resistance in metal, you increase the temperature. The metal’s ions will vibrate with an increased speed and collide with free electrons, which drives up both metrics. As a result, corrosion can cause your wires to get hot.

Loose Connection

Loose connections also tend to increase the resistance in a cable. If you do not tightly secure the cable, the current will not flow through the starter.

Instead, the ions and free electrons will build up at the end and collide with one another. The fast vibrations of the ions generate heat, which can cause your positive or negative battery cable to get hot.

Starter Troubles

The starter places the largest electrical load on the battery because it draws a substantial amount of current from the battery. If you have a new cable and a tight connection, you may have starter troubles.

Sometimes, starters have body grounds rather than grounding wires. You can check if your starter is having issues by connecting it to an ohmmeter reading with two-ohm accuracy. 

Connect one lead of the ohmmeter to the red wire on the starter solenoid. Then, attach the other lead to the body. Turn the starter gear manually and see if you experience a dead short.

The starter should have a resistance reading of around one ohm. Anything that drops below 0.6 ohms indicates that you need a new starter.

Why Is My Battery Terminal Glowing Red?

Your battery terminal may glow red if it corrodes or has a loose connection. When it glows red, you still have time to fix it. Ensure you turn off your vehicle and disconnect the cables to clean or tighten them.

What Would Cause a Battery Terminal To Melt?

A battery terminal may melt if the temperature increases past the melting temperature of the metal. The resistance has exceeded a critical point, and you can no longer save the cable. If it starts to melt, you will need a new cable.

What Do I Do If My Battery Cable Is Hot?

If you have a hot battery cable, start by turning off your engine and disconnecting the cable. You will need to clean any corrosion and secure it tightly.

Cleaning Corrosion

Mix baking soda and water in a bowl. Using a brush, scrub any corrosion off the surface of the wire, starting with the negative terminal. Wash off the baking soda with water. Ensure you rub a little wheel bearing grease to increase the corrosion resistance.

You can also use drinks with carbonic acid like soda. Pour soda on the terminals and rub off the residue with a sponge.

If you have an extreme case, soak each terminal in a baking soda and water solution for 20 minutes. Then, use a brush to scrub any remaining residue. You may need to soak it again in soda and rub off what remains.

Wipe them clean with a damp cloth and let them dry before reattaching them.

Tight Connection

When reconnecting a battery cable, rub some grease on each terminal. Start attaching from the positive end. Screw it until you cannot go any tighter.

Be careful when working with brass cables. These are more susceptible to breakage from overly tight connections. If possible, try to invest in a copper or bronze cable for durability.

What Are the Signs of a Bad Battery Cable?

You might have a bad battery cable if you experience any of these troubles:

  • Corroded battery terminals
  • Issues starting the vehicle
  • No power transfers from the battery to the vehicle
  • Clicking noises when you start the car
  • Visible damage

Keep in mind that these issues can occur on cars, boats, golf carts, and any other vehicle.

Do I Need To Replace My Battery Cables?

Even after you tightened the connections, cleaned the corrosion, and checked the starter, your cables might not work. In this case, you will need to replace your battery cables.

Time

Generally, battery cables last between 50,000 and 100,000 miles.

Cost

Paying for a battery cable replacement will cost between $299 and $329. This price estimate includes the cost of components ($223-$232) and labor ($76-$96).

High-quality cables typically cost more. If you want to minimize the troubles you experience with your battery cables, avoid lead ones. They may cost less upfront, but they need more frequent maintenance.

Also, you can spend less by performing the replacement yourself.

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