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What is a ESC for on a RC Car
By Joe Rich
What is an ESC? When I was building a RC car recently i was getting ready to set up the electronics and a question popped into my head. What is an ESC or electronic speed controller and how does it work? Are they easy to set up? What is the difference between a brushed and brushless ESC? Can brushless work with a brushed motor? Or vice versa?
Well today we are going to find out.
- What an ESC actually is.
- How an ESC works.
- Brushed and brushless ESC what is the difference.
- How to test an ESC.
- How to waterproof a ESC.
- Can you repair an ESC.
Before electronic speed controllers
A few years ago speed controllers were manual this required the controller to be connected to a servo.
When the throttle was moved forward or backwards the servo would move a arm along a metal contact this would make the car accelerate or reverse.
Electronic speed controllers did away with all this no need for the servo and all the wiring and set up that it required.
The biggest problem with the manual speed controller was that they were prone to getting jammed especially when the battery was running down.
I have crashed many times this way.
Manual controllers are still popular with some old school RC car people.
So it was a great advance when electronic speed controllers were introduced.
What is a electronic speed controller
An electronic speed controller is a device that allows the user to control the speed and power to an electric motor.
This principal is the same for brushed and brushless ESC.
Most modern brushed and brushless ESC’s incorporate a circuit to regulate a stable voltage to run the receiver this removes the requirement to have to carry an extra battery pack in the model.
How an ESC works
What an ESC does and how it works is really quite simple.
The ESC receives a input signal form the receiver which is set by the throttle position on the transmitter.
This signal is PPM Pulse Position Modulation.
What it does is take this signal and transforms it into a current to be drawn from the battery to power the motor.
So it is in effect a power manager.
This current is then fed to the motor and away you go.
They are also capable of providing a suitable supply of energy to power the steering servo.
Brushed and brushless ESC what is the difference?
One of the most common questions asked is can you use a brushed ESC with a brushless motor and can you use a brushless ESC with a brushed motor.
Well the simple answer to that question is NO.
Brushed ESC with brushed motor and brushless ESC with brushless motor.
So what is the difference between a brushed and brushless ESC?
We will start with the brushed ESC.
Brushed ESC are DC brushless re AC.
As we said earlier the ESC manages the power sent to the motor.
When the motor begins to spin the armature inside the motor there are little brushes in the stationary portion of the motor these make contact and provide voltage to the commutator which energizes the terminal for each pole or electromagnet of the motor. As the motor turns the voltage supplied to each pole changes.
To control how fast the motor spins a brushed ESC simply turns the voltage on and off very rapidly several times a second.
To increase the speed, the ESC simply increases the amount of time that the voltage is turned on while decreasing the amount of time that the voltage is turned off.
When you want to slow the motor down, this process is reversed.
ESC’s for brushless motors are very different to ESC’s for brushed motors neither are compatible with each other.
You must use a brushless ESC with a brushless motor and a brushed ESC with a brushed motor.
To identify which is which as a brushed ESC has 2 motor wires and a brushless ESC has 3 motor wires.
Brushless ESC are AC brushed are DC.
Brushless ESC are vastly more advanced than brushed they can be programmed with different firmware for many types of applications.
On a brushless ESC there are 3 wires as opposed to a brushed ESC having 2.
This is because there are 3 pick up magnets every 120 degrees on a brushless motor.
This is basically a 3 phase motor.
When the motor spins each magnet is energized with a pulse of current by the ESC to move on to the next magnet.
The biggest difference you will see with a brushless ESC and brushless motor is a major increase in power.
How to test a ESC
If you think you have a problem with your ESC here are a few tips to check to see if repair or replace is required.
One thing to bear in mind it could be the motor that is at fault.
The first thing that I would do is check all the wiring check that no wires are broken all soldered wires are in good shape.
Does the ESC make any noises when powered up?
Check the physical condition of the ESC.
Smell the ESC is there a burnt smell? if there is then probably it is toast (no pun intended).
How to waterproof a ESC
Back when i started in RC cars you had to either avoid water altogether or try some homemade methods to waterproof your electronics.
This would involve some really messy work.
What you would do is remove the casing and paint the boards with liquid electrical tape.
This method works really well one thing to note that if you try this do not get any of the liquid tape on the heat sink or fan if fitted.
It is possible to waterproof your ESC with a balloon it is a bit of a fiddle to get the ESC in or you could use a plastic bag and elastic band.
Balloons are better because they are a good tight fit.
This is a very cheap and reliable way to waterproofing but be careful not to split the balloon when fitting.
But these days most manufactures make their ESC already waterproofed.
Using your RC car in the wet is a lot easier and quicker so the fun does not have to stop.
Can you repair a ESC
Well that depends on a few factors.
On an environmental stand point it would be great, better to repair and recycle than rip out and throw in the refuse.
But you may think the cost to effort is not worth it.
Do you have the skill set to pull apart and repair very delicate intricate wiring and soldering.
Are there spare parts available for the make and model you want to fix.
The ESC is one of the most important of all your RC car components it takes a lot of punishment with dirt, dust, water, vibrations and temperature variations.
So it is important to keep the dirt and dust build up to a minimum.
This will ensure a long and reliable life.