This guide aims to give you a basic understanding of Electric Speed Controllers (ESC).
ESCs take the throttle signal from the receiver and control the power to motor in the model.
Brushless motors work on three phase signals being sent and received from the motor.
This can be seen with the three leads that connect the ESC to the motor, with the ESC sending signals to
the motor to make it turn as needed.
ESCs handle a lot of power when regulating the power to the motor. In doing this the ESC generates heat which is dissipated through the heatsink. ESCs should be kept as cool as possible to prevent them from overheating. Positioning them near air intakes where continuous air passes over the heatsink is
an ideal way to keep them cool.
Standard ESCs have features and settings that can be adjusted to suit the motor and model. These normally include:
- Motor timing - to adjust the timing the ESC sends signals to the motor.
- Brake - to stop the propeller rotating when at idle throttle or let it rotate
freely.
- Model type (car, plane or helicopter).
- Start-up acceleration speed.
- Additional settings are available for ESCs that have Battery Eliminatory Circuits (BEC) features.
The most common method to change an ESC setting is using the radio transmitter. With this method the ESC enters a programming mode and beeps a number of times to indicate the setting that can be configured. Through movement of the throttle, settings can then be changed. Programming via the transmitter can be a confusing process and requires a lot of attention.
If supported by the ESC, other methods are available to programme your ESC. Some of these include using a Program Card which involves connecting the ESC to a battery and the Program Card, then changing the desired setting on the Program Card. The new setting gets saved back to the ESC and the process can then be repeated for all needed changes.
Other methods include connecting the ESC to your computer via a USB cable and change the settings using the manufacturer supplied software.
There are two versions of ESC that are available. One that features Battery Eliminatory Circuits termed BEC and one without, known as OPTO.
ESC BEC aims to remove the need for separate equipment to power the radio control (RC) equipment in the model, namely the receiver and servos. The ESC BEC will power the receiver and servos from the connected main power pack.
OPTO requires you to have separate circuitry to power the RC in the model such as a Voltage Regulator (see right) or UBEC unit.
BEC comes in two forms, Linear BEC known as just BEC and Switch-Mode BEC which with also known as SBEC or UBEC.
Linear BEC is suitable for powering a low number of servos due to the low current requirements. As the circuitry is linear the amount of current falls as voltage increases so performance in the RC can degrade as load increases.
Switch-Mode BEC is suitable for a larger number of servos and especially several digital servos that require more power. As the circuitry is switch based a consistent amount of power is supplied to the RC equipment as the power load varies so performance can be predictable.
The ESC manufacturer should state how many servos the built-in BEC can safely support so it
is best to check these specifications.
Choosing a RC power setup has many factors. Here we'll try and look at each concern:
Weight
If you require a lightweight setup then ESC BEC is the best solution to keep the weight at a minimum.
Redundancy
If you want peace of mind in case of an ESC failure then an OPTO based solution with a Voltage Regulator or UBEC powering is best for you. For another level of redundacy you may also add a separate battery to power the RC through the UBEC, but this is at the expense of additional weight.
Servo Performance
To guarantee the peformance of your servos then either an ESC Switch-Mode BEC or an OPTO based solution should be considered. Linear BEC is not recommended.
No, you can always connect your Voltage Regulator or UBEC to your main battery. Just check
that your unit can handle the output voltage of the main battery pack. The UBEC will draw power that the motor could be using, but this is a lightweight alternative to a separate battery pack just for powering the RC.
If your ESC doesn't have a programmable option to turn the BEC on or off, you can simply pull the red wire out of the connector on the lead that goes from the ESC to the receiver. This method prevents the ESC from sending power to the receiver and you can then use your separate BEC. Pulling it out rather than cutting it means
that you can reconnect it if you want to use it at a later date.
For ESCs that have a switch fitted, just leave this turned off.
Have a browse of our ESCs by clicking here. If you need any help, just call us on 0845 539 2103 (local rate) or email us at Shop@TopProps.co.uk where we'll be glad to advise you.
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