The most important tool that every RC Electric Hobbyist must own is a temp (temperature) gun of some sort! You ask why? Well it will save you lots of money, that is why.
It doesn’t matter if you build your RC models or don’t. Having a temp gun in your toolbox will certainly help out. Heat is the worst enemy for any part of our electric power system. Managing the heat that is generated by our RC components is what will help save them. Too much heat that builds up in any electrical part of the power system can certainly destroy that component.
There are many temp guns out there that you can pick up. I have been using the Duratrax Flashpoint infrared temp gun for so many years. It is very easy to use and very cost effective.
How to use a Temp Gun Effectively
Periodic spot checks must become a standard for you as you run your RC vehicle. What you will want to do is every 5 runs of your RC vehicle, check the temperature of the brushless motor and electronic speed controller. To get an accurate reading, the measurement must be completed within 30 – 60 seconds of the RC vehicle coming to rest. Waiting too long may allow your heat sinks to remove heat providing you with a false reading. Next, you will want to use the temp gun as instructed in its manual. For best results, take measurements of many different locations on the motor and ESC. Allow the temp gun to read and retain the maximum temperature as you are taking readings from multiple different locations.
As your LiPo batteries begin to age, you will want to make certain that you are measuring the temperatures once every few runs. LiPo batteries will produce more heat when their internal resistance begins to rise as they age.
Factors that influence Temperature Readings
Keep in mind that there are many influences on the temperature of these components. These factors will skew your readings. What you want to watch out for is any sign that the power system is under higher then normal load. Here is a list of factors that can influence your running temperature.
- Higher Ambient Temperatures (outdoor temperature for example)
- Increased load on motor with aggressive throttle use
- Binding of Driveline Components
- Aging LiPo batteries
- Length of Run Time
Using a Temp Gun for the First Run of a New Build
When running your setup for the first time, you want to be certain that you have selected conservative gearing or prop sizes. In RC Airplanes it is much easier to bench test your system. You are able to run up your motor and take measurements every 45 seconds. For an RC car or boat build, you will have to run bring the vehicles in after 45 seconds. At this point take measurements of the motor, ESC and LiPo batteries.
If all components are well under 140F/60C, run the vehicle for another 45 seconds and return to take measurements. Keep increasing the run time by 45 seconds if all components are under 140F/60C up to the maximum run time for your system.
If the temperature exceeds the safe limit, either the maximum allowable run time or maximum continuous load has been exceeded. Reduce the load and or run time and check the system again.
Determining Maximum Run Time
In the process described above, determine your total run time that will drain 80% capacity of your LiPo’s. Each time you run the vehicle for the 45 second period and reach about 3 total minutes, it would be a good idea to record how many mAh is placed back in to the LiPo Battery. Determine the amount of mAh that is placed back in the battery by charging the single battery and recording the value on the charger.
For example – If you were to get a 4 minute 15 seconds run time and replace 4000mAh from a 5000mAh battery, this should be considered your maximum run time. 80% of the batteries capacity has been drained. This is to ensure Long LiPo life while getting the better part of a batteries discharge curve.
To the run time calculator to help calculate run time based off of elapsed time and capacity placed in to the pack.