Boat Battery Cables Get Hot When Cranking – What to Do?

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Boat battery cables are cables that have circuiting wires and are used in boat applications and designed to resist water and corrosion when exposed to the water surface. They exist in many forms, such as GPTM. Sometimes boat cables can get hot while riding the boat, and you will have to make a quick stop to repair the cables before the whole ship is blown out.

Several reasons result in boat cable becoming hot, such as poor cable connections, cables have undergone corrosion and high voltage. Boat cables require immediate fixation to avoid blowing out the battery while in the middle of the ocean or sea.

Table of Contents

Reasons that cause boat battery cables to get hot when cranking

First, the boat cables may corrode due to accumulation on the cable terminals. If the cable terminals are dirty, a thin corrosion film is created on the terminals, which resists current from the battery to the boat engine.

The resistance made decreases the amount of voltage and increases the heat on the boat cables. The corrosion can blow out the boat engine or the batteries. Once your boat cable starts corroding, make a quick stop and try to fix the cable problem.

boat battery cables get hot

Secondly, too much power flows through the cable. Once your boat battery is damaged, many currents are transmitted to the boat engine, and if the current is more than that which the cables can handle, the wires become hot, and they can even blow out. Once you have noticed incorrect current flow, try fixing the battery by replacing it with the spare battery to prevent further battery and cable damages.

Boat battery cables can also get hot when cracking due to poor cable connection. If you disconnect your boat cables, the cables can get hot. Also, if you use faulty cables when connecting, the cables can drain a lot of currents. A large amount of current drawn from the battery starts damaging the boat cables, resulting in the cables getting hot.

Signs of a bad battery cable

The following signs will help you identify the boat battery cables are faulty.

  1. The car engine fails to start because the battery cables fail to transmit current into the engine.
  2. Engine functions are slower than usual due to limited current access.
  3. Decreased interior power in your boat.
  4. A dead battery that is not charging at all.

How the check the boat batteries to see if they have become hot

It is advisable to check the boat battery cables before you begin sailing.

  1. Check the positive terminals of the boat battery cables to see if the terminals are correctly connected. Examine the battery cables and ensure that they are in good condition for transmitting current to the boat engine from the battery. Finally, check if dirt has accumulated on the terminals and try cleaning the terminals using recommended material to prevent the cables from corroding.
  2. Inspect the negative terminals of the boat battery cables. Also, clean any dirt that has accumulated on the terminals. Check the connections if the terminals are correctly matched with the battery and engine terminals.
  3. Examine the cables if they have worn out. Check any cable cuts or breakages that can expose cable wires. Ensure you fix the damage or cut cables before using them. Moreover, ensure loose cables are tightened to enhance proper current flow from the battery to the boat engine.
  4. Replace your boat battery cables if they are completely damaged or once they start showing the signs above.

How to repair damaged boat battery cables

1. Identify the type of battery cable required

Firstly, read the manufacturer’s manual and see the type of boat battery cables required for your replacement. Buy the identified battery cables and try fixing them in the correct position. The battery cables for replacement must be of high quality and function as required.

2. Remove the boat battery

Before examining battery cables, remove the battery from its position to view the battery cables. Ensure you handle the boat battery carefully to avoid damaging the cables and even the batteries. Use correct tools like a screwdriver to unscrew the bolts from the battery terminals before removing the batteries.

3. Locate the position of battery cables and examine them carefully

After removing the boat battery, find the position of the boat battery cables. Examine the boats carefully and identify any problems affecting the cables, such as loose wires and blown-out cables.

4. Strip the cable using a wire stripper

Strip the cables using a wire stripper and examine the wires. Isolate the damaged wires from good cables. Ensure you cut off the wrong cables correctly to avoid interfering with the undamaged cables. If the cables are blown out, consider replacing the whole battery cables. After removing the bad wires, clean off the cables to remove any dirt that corrodes the cables or the wires.

5. Reinsert new cables into the correct location

Install new wires in the correct position and match them correctly. If you fail to match them as required, your boat engine will not start since there is no current flow to the engine. Also, tighten the wires while installing them to allow current flow to the engine. Finally, close the cables well as recommended.

6. Test the reinstalled cables if they are working well

Once you have successfully replaced the wires, test the whole battery cable if functioning as required. If the cable fails to work, recheck how you installed the new cables and check the terminals if they correctly match the battery and engine terminals. If not, try to reinstall the wires or rematch the terminals correctly.

7. Replace the boat battery cable

If your battery cable has been corroded or blown out, consider replacing boat batteries that the manufacturer recommends. If the problem persists, try contacting a professional to help you troubleshoot the battery cable problem.


Replacing boat battery cables results in several advantages, such as increased boat battery efficiency and prolongs lifespan of the boat. Sometimes you can experience boat battery cable problems which you are unable to troubleshoot on your own. Luckily, you can now troubleshoot the problem by following the simple steps above.

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