While power system computation programs are a good start in determining anticipated loads on the various components, ultimately directly measuring the electrons coursing through your model is the best way to ensure that you aren’t overstressing your motor, ESC or battery.
The DCM is the Wattage version of a multifunction, multi display unit that will give you important measures. This is out of production now but there are several similar units out there. You insert the DCM inline between the battery and the ESC. When you run the power system, the DCM measures voltage, amperage, watts and mAh used. The instructions demand that the battery connectors be replaced if you plan on using systems pulling more than 10 amps. Unless you limit your fleet to small park fliers, you’ll want to do that. Clip, solder and you’re good to go. Why high capacity connectors aren’t used is a mystery to me. The warning is well worth abiding, however. I plugged adapter wires onto the DCM to connect my Dean’s connectors. After a quick test run on a new motor I discovered that though the amps reading had been low, the motor was quite hot. After changing out connectors I discovered the reading was WAY more than indicated with the adapter wires. Imagine that, the engineers who build it actually knew what they were talking about.

The specifications state the following measurement ranges:
Minimum input voltage: 3V
Maximum Voltage: 60V
Amperage: 0 – 99Amps
Watt-Range 0 – 6000
mAh used: 0 – 9999mAh

Using this or one of the similar models out there is very important to your models’ power system longevity. Your motor, your ESC and your battery all have amp limits. The propeller you choose impacts this measure. You may want to experiment with props to get the speed and power combination that fits under the amp limit of the lowest rated component in the system.

The measurements are also helpful in anticipating performance. Watts per pound is often used in anticipating performance. Many suggest a watt per pound ratio of 50 – 75 watts per pound for trainers, 100 watts per pound for sport models and 150 watts per pound for aerobats and 3D.

This is not a tool that you’ll be using every day. Unless you really get a kick out of wringing the most from your power system or changing props to meet the requirement of the day, you’ll probably check your configuration once and let it go. Not checking it at all, however, would be a mistake for all but the RTF park flyer beginner kits.

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Visit modelaircraft.org/gov to learn about pending federal regulations on model aircraft.