Electronic Speed ControlWith technology continuing to develop light-weight and efficient power supplies, it’s not surprising to see an increase in popularity of the number of electric powered rc airplanes, helicopters and gliders. Combined the demand with continuing drops in cost you soon realize that electrics are a great way to get into the world of rc.

Electronic Speed Control (ESC)

Think of an electronic speed control (ESC) as acting like a 1) power manager, 2) and a brake.

First, the power supplied by your batteries, to your motor, is either “on” or “off”. So without something between your motor and the battery, regulating the current, you are either running at full power or not. An ESC acts like a power manager and allows you to control the amount of current (or power) that you want to go to your motor giving you your throttle.

So why would you need a brake on an electric motor? You need a brake on your motor if you are using, for example, a folding propeller on a powered glider. Activating the break (via the ESC) ‘locks’ the motor in place and prevents the motor from spinning. This, in turn, prevents your propeller from spinning freely, allows it to fold, and helps increase your aircrafts aerodynamics.

An important thing to remember when choosing an ESC is to properly match an ESC to your motor. Most all electric rc motor manufacturers provide this information for you in the manual. Additionally, be sure to purchase the right ESC for the right motor. You cannot use a brushed ESC with a brushless motor or vice versa.

Battery Eliminator Circuit (BEC)

The battery eliminator circuit (BEC) is designed to deliver electrical power to other electronics in your aircraft without the need for a separate battery. Unlike the ESC which allows you to vary the voltage (i.e. throttle) to your motor, the BEC maintains a fixed voltage to your radio and servos ensuring you have control over the aircraft.

So what happens when your battery is dead or nearly dead by the end of your flight? Do you loose control of the aircraft? Go into a death spiral? No. All BEC equipped ESCs have what is called a low-voltage cut-off feature preventing you from draining the battery so much that you no longer have control of the aircraft.

When your battery voltage becomes critically low, the BEC will continue to provide proper power to the controls but, at the expense of the motor. In turn, the power reduction to the motor tells the pilot it is time to land before they completely loose all power to the aircraft.

On thing to keep in mind: If you are using LiPo (Lithium Polymer) batteries to power your model, you never want to completely drain the battery during flight. Completely draining the battery can result in battery damage to the point where it will no longer hold a full charge or not charge at all.

It’s always best to land immediately once you begin to realize you are loosing power to the motor.

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