When RC Motor wires melt or get very hot it usually means one thing; more current is flowing through the wire than it is designed to handle. The solution is as simple as upgrading to a larger gauge (larger diameter) wire. However, there may be a problem elsewhere that needs looking at, so it is best to check things out first.
Why does the motor wire get hot?
When a current flows through a wire there is a certain amount of resistance to the current flow. When current is resisted, the wire heats up. The thinner the wire, the less current it can handle (more resistance to current flow) and the hotter it will get. If the wire gets too hot, the outer casing can melt off. If this happens, the wires can short out (touch together) and damage your electronics.
Common reasons for high currents flowing
- When you upgrade to a more powerful RC Motor / ESC system
- If the car is binding somehow
- If you are using a very high gearing setup (low gear ratio) for top speed
The solution to the problem depends on what is causing the high current:
ESC/Motor upgrade
Standard or stock motors (such as the silver can 540 motor) don’t demand a great deal of power and current so are usually fitted with fairly thin wires – which are fine for these motor types. If you’ve just upgraded your Motor / ESC but used the old thin wires from the 540 motor, the new motor is probably drawing a lot more current than the thin wire was designed for.
Solution
Simply replace the motor wires with a larger gauge wire (thicker diameter) that can handle more current.
Wheels, bearings or parts binding and putting extra strain on the system
If there is something binding/jamming or stopping the wheels from rotating freely, the motor will have to work a lot harder. Harder work for the motor means drawing more current causing the motor wires to get hotter than they normally would. This will also drain your battery quicker, so you will have shorter run times each charge.
Solution
Check free movement of bearings, wheel bolts are not over-tightened, check that the wheels spin freely and that the gearbox is also free and smooth with minimal friction. Check any drive shafts or belts are working smoothly.
Make sure that the car rolls along the ground freely and easily when no motor is engaged (temporarily remove the pinion to check free movement). This will not only improve performance, but it will also give you longer run times due to higher efficiency.
Gear Ratio too low (geared for high speed)
If you are using a very low gear ratio (largest pinion and smallest spur gear) to get maximum top speed from your RC vehicle, this will make the motor work harder on acceleration, meaning higher currents. The motor itself will also get hot due to the hard work it is doing.
Solution
Change to a slightly higher gear ratio – this will help keep the motor and ESC cooler, and should also reduce the currents that flow through the motor wire.
This is particularly important when using the RC car off road – rough terrain equals more rolling resistance and more work for the motor. Higher running temperatures and higher currents can flow when running your rc car off road.
Conclusion
Soldering larger gauge wires is an easy way to solve the problem when RC car motor wires get too hot or melt, but it is always best to check and ensure the RC vehicle is running smoothly and freely as it should.
Also see when battery connectors melt or overheat.