How to Check If ESC Motor Pads are Short-Circuited

Ensuring that your motor pads are not short-circuited is crucial for the proper functioning of your drone. Small drones, in particular, have tiny solder pads that can easily harbor dirt or become short-circuited. In this guide, I will share a simple and effective method to check if your ESC motor pads are short-circuited, using both practical and technical insights.

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Why Multimeter Is Not Useful In This Case

If you’re working on a small drone, you know how tiny and delicate the solder pads can be. Dirt and other contaminants can easily cause issues. Sometimes, even if you use a multimeter to check adjacent motor pads on an ESC, you might hear a beeping sound indicating a short circuit.

However, this is not always a reliable indicator when the motor is soldered to the ESC, because the internal resistance of motors is typically very low, often less than 100 milliohms. This low resistance can cause the multimeter to incorrectly signal a short circuit. Therefore, relying solely on a multimeter can lead to false conclusions. Instead, I will show you a more reliable, practical method to check for short circuits in your motor pads.

The Practical Method

A practical method to check for short circuits involves spinning the motor manually. Here’s how you can do it:

1. Spin the Motor by Hand: After soldering the motor wires to the pads, try spinning the motor with your hand. Pay close attention to how it feels.
2. Check for Continuous Spinning: A motor that is not short-circuited should spin freely and continue to spin for a short while after you stop applying force.
3. Feel for Damping: If the motor stops spinning almost immediately and feels like it has a damping effect, this is a strong indicator that the motor pads are short-circuited.

Try it Yourself

You can actually try this by connecting two of the motors wires together to simulate a short circuit at the pads. Try spinning the motor by hand. You will notice that it cannot spin continuously and stops almost immediately. Now disconnect the motor wires and spin the motor again. This time, it should spin freely and continue to spin for a while.

What to Do If There’s a Short Circuit

If you notice that your motor pads are short-circuited, you should:

1. Inspect the Solder Pads: Check for any visible dirt or solder bridges that might be causing the short circuit. Clean the area thoroughly.
2. Check the ESC: If cleaning the pads does not resolve the issue, the problem might lie with the ESC. Inspect the ESC for any signs of damage.
3. Test All Motors: It’s a good practice to spin all four motors by hand after installation to ensure that none of them exhibit damping. This simple check can save you from potential issues when you power up your drone.

Conclusion

Checking whether your soldered motor pads are short-circuited is a straightforward yet essential step in maintaining your drone’s health. By using the method of spinning the motor by hand, you can easily detect any short circuits that might be present. This practical approach, combined with careful inspection and cleaning, ensures that your drone’s motors are functioning correctly and helps prevent potential damage to the ESC.

Remember, the key is to look for that smooth, continuous spin. If you feel any resistance or damping, take the necessary steps to address it immediately. This simple check can go a long way in ensuring the longevity and performance of your drone. Happy flying!