When testing electronic speed controller (ESC) temperatures in RC vehicles, you might assume that lower throttle results in less heat. However, real-world testing shows the opposite. By measuring current outputs at 100 amps (100% throttle), 75 amps, 65 amps, and 50 amps, the temperature results revealed some surprising patterns.
ESC Temperature Testing
The chart below tracks ESC current at full throttle (100A) and lower throttle levels. Interestingly, operating at partial throttle produced higher temperatures than at full throttle. Even at half current, the ESC ran hotter than at full throttle.
| Throttle / Current | Average Temperature (°C) | Peak Temperature (°C) |
|---|---|---|
| 100% / 100 A | 39–40 | 45 |
| 85% / 75 A | 57 | 63 |
| 80% / 65 A | 50–53 | 59 |
| 75% / 50 A | 47 | 53–54 |
Why Partial Throttle Generates More Heat
This occurs due to how the ESC manages power at partial throttle. At full throttle, the ESC applies 100% voltage to the motor without turning off any part of the phase. At partial throttle, each phase is turned on only part of the time—for example, 50% throttle means the phase is on half the time and off half the time. The ESC rapidly switches the voltage on and off thousands of times per second (around 8,000 Hz in this test), which requires additional work and generates extra heat.
System Efficiency Observations
Measuring system efficiency across throttle levels revealed on the chart below. This confirms that ESCs work harder at partial throttle than at full throttle, generating more heat despite lower current. The system is most efficient when the throttle is at 100%. Data collected here was on a motor dyno measuring electrical and mechanical performance.
| Throttle Percentage | System Efficiency (%) |
|---|---|
| 20% | 35 |
| 50% | 50–55 |
| 85% | 78 |
| 100% | 77–78 |
Final Thoughts
Testing ESC temperatures demonstrates that running full throttle is actually safer for your speed control than running at partial throttle, provided you stay within safe limits. Understanding how your ESC handles different throttle positions helps maintain system performance and prevent overheating in your RC vehicle. It also gives you that peace of mind, knowing that your ESC actually is not working as hard at full throttle! Why is this important. Well, of course, we love full throttle!