In this video, I tested a simple idea: adding extra magnets to my previous brushed DC motor. The goal was to see whether stronger magnetic fields could improve performance, especially torque, without changing the coil or increasing the voltage.
This is part of my series where I test different improvements to homemade DC motors. In this article, I’ll explain what I did, what worked, what failed, and what I plan to do next.
Why I Added Extra Magnets
Every brushed DC motor runs on a balance between current, magnetic field strength, and coil design. Since I already tested brush upgrades and coil changes, I wanted to experiment with magnetic enhancement.
I reused the same motor I built earlier (see how I built it here). Aluminum tube as commutator, soft copper brush, and a simple coil with 2 neodymium magnets.
I used neodymium magnets, placing them directly on top of the existing ceramic magnets inside the motor housing. These magnets are very powerful and easily available, so I wanted to find out if they could increase torque just by boosting the magnetic field strength.
Stronger Torque – Yes!
As soon as I started the motor, I noticed an improvement. The motor was harder to stop by hand. It resisted more, meaning that torque had increased. This is exactly what I was hoping for.
A stronger magnetic field gives the coil more force per amp of current, which means the rotor turns with more mechanical strength. This could be useful for driving heavier loads.
No Increase in Speed
While the torque increased, the RPM (speed) didn’t change much. That’s expected. Speed in brushed DC motors mainly depends on applied voltage, back EMF, and brush-commutator efficiency — not just magnetic strength.
If you want higher speed, you’d need to improve coil design, reduce internal resistance, or increase input voltage.
The Commutator Failed Again
Unfortunately, the aluminum commutator I used for this test failed again. It burned out after a few seconds of running. The heat caused it to oxidize and lose conductivity. This is a major limitation I keep running into when using aluminum instead of copper.
It also turned black and stopped transferring current to the coils. This stopped the test earlier than I planned.
Lesson Learned: Don’t Use Aluminum
Aluminum may be lightweight and easy to shape, but it’s not suitable for commutators. It overheats fast, doesn’t conduct well under pressure, and wears out quickly.
In future upgrades, I’ll definitely switch to a copper commutator, even though it takes more time to cut and shape. Copper is more durable, conducts better, and won’t burn out during short tests.
My Motor Setup
- Insulated copper wire (0.6 mm) for two rotating coils, 40 turns each
- Thin copper wire brushes (0.5 mm)
- Aluminum commutator
- Power source: by 12V, 1.6A
Join My DIY Motor Journey
This is just the beginning. I’ll keep sharing more upgrades, fixes, and fun experiments with motors and DIY builds. If you’re into simple science projects, electronics, or just love creative hands-on ideas, come along!
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