Understanding Electricity – For RC vehicles

Introduction – Understand Electricity

Your complete Guide to understanding Electricity specifically for all Radio Control Applications.

If you wish to learn more about the electric side of Radio Control Vehicles such as RC Planes, Boats, and Cars, you have come to the right place. Here we will discuss everything from the basics of electrical terms to avoiding that discouraging component failure.

Electrical Vehicles in this day and age are full of excellent advantages over other power sources. They are clean, quiet, land generally offer low maintenance. However, there is the one aspect of electrical systems. If you are modifying, or piecing together your own power system, it is necessary to have a basic knowledge behind the electronics in any system or to get the required help necessary. Over the next several pages several key relationships will be identified. To read further, visit the relevant section on the left side bar or follow the given order.

If you are familiar with basic terms and the difficult to understand definition of electricity but want to read further, skip to the Theory, Relationships, Concepts and Formula page. Here will be the majority of all major concepts that effect your complete power system in a Radio Control RC Planes, Car, Boat.

Electricity Definition – Understanding Electricity

Electricity is one of the more difficult concepts of today that is often difficult to understand. The term electricity is one of the hardest terms to understand. Although it is used often, it has several meanings depending on how one would use it.

For the simplicity and sake of Radio Control Boats, Cars and Planes, we will define electricity as the flow of charged particles called electrons, through a conductor. Electricity in this manner is difficult to understand for several reasons. The main reason is visibility. Flow of electricity through a wire is impossible to visually see. Since electricity occurs more at an atomic level, it is impossible to see it flow through a wire. It would probably be very difficult to learn how to drive a car if we could not see, so how do we grasp the basic concepts of electricity in its flow type form?

To help us with detecting when or how much electricity is present, we have tools and special formulas, laws, and concepts to use. Common tools we could use to measure electricity in different ways are an ammeter, voltmeter, also known as a multi-meter or a device used a lot in Radio Control boats, planes and cars called a data logger. How to use these items will be covered in the Measuring Electricity link.

Formulas, laws and relationships will be covered next .

Electric Theory – Understanding Electricity

Here we will discuss all Relationships, Formulas, and Concepts that relate electricity and Radio Control Planes, Cars, and Boats.

Ohms Law – Understanding Electricity

This law is the most popular and well known concept or relationship. It is typically taught and remembered from high school. Ohm’s law takes voltage, current and resistance and applies a direct proportional relationship between them. It is best defined as V = I R where V represents voltage in volts, I represents current in Amps and R reperesents resistance in ohms.

The second most well known formula is the power equation. The power equation relates the voltage, current and power variables. It is said that P = I V where P is power in watts, I is current in Amps and V is voltage in volts.

The manipulation of these two very simple equations can yield several other equations.such as:

V = IR or I = V / R or R = V / I
P = I V or V = P / I or I = P / V

We can derive other equations by substituting both equations
For example, substituting the formula V = IR in to the formula P = I V will result in the following formula of P = I I R ( I squared )

Just from these simple formulas, it is easy to see that if R remains constant (R could be a motor) and V increases, the end result to current is it increasing as well. This would be a simplified state of what is actually happening. The actuality behind this is that a motors resistance is always changing as the voltage and current in a system. The main point to understand is we can use these simple formula’s to determine or predict what may the outcome be.

Another example is if we wish to reduce current in order to reduce heat but keep power levels the same, we can see that if voltage increases, current must decrease from our P = I V formula.

How do we know decreasing current, decreases heat? – Understanding Electricity

Well let’s look at the formula we derived earlier. Where P = I I R. We will assume the resistance will be the total resistance in our ESC and the power will then be related to the resistance in the ESC. It is important to understand what we are working with here. The Power will be the power dissipated by the resistance in the ESC.

What does a resistor provide in terms of power? – Understanding Electricity

A resistor of course gives off heat. So that means if the ESC has the same resistance as before we thought of this idea (which it should) we can use the formula to determine if we are in fact reducing our heat output. If R remains constant and I decreases, we can see from the formula that the Power output must also decrease. This is true even if the reduction in I is only slightly reduced. Reduced Power in our resistor ( ESC ) represent and confirms that decreasing the current can improve the heat output of the ESC at the same given power level.

Before I continue I want to be sure no one is confused on how we are using the power formula. When we think power, it’s easiest to visualize power from mechanical motion. However we are using the resistance value of the ESC. If we want the power created by the motor which resistance value would we use? Of course, the motor.. Although this is correct, the resistance in a motor is always changing. It is the lowest at the lowest RPM. That means at 0 RPM the motor will draw the most power. This makes sense as we know Brushless motors produce lots of Power in the low RPM range. Low resistance at constant voltage means amperage is high. As the motor begins to spin at higher RPM’s the resistance of the motor increases.

This makes our formula that we derived, much too hard to use here as the variable needed is constantly changing. This is where we would use a formula that is better suited such as the original P = I V. On the next tab, measuring electricity, we will discuss how to get this information as it is very useful to us.

Ultimately the changing resistance in a motor defines the way it operates in terms of power output. If we take any motor and connect 10v it will spin at the RPM equal to it KV multiplied by the 10v. At this value there is a certain Current produced. If we load the motor with any load such as a brake on the shaft, we know that the slower the motor rotates the lower its resistance will be. From this we can conclude that the increased load placed on a motor will increase the current demanded by the motor.

Why is all this important? – Understanding Electricity

We are after a certain power output in order to correctly power our models. In some cases you may want to up the power and do so by increasing voltage. If the load is equal we now know the current will increase. We also now know that increasing current will in turn increases heat output.
Heat in our motors, ESC’s, and Batteries is ultimately what reduces their life span or lets the magic smoke out.

If we have the proper knowledge and equipment we can nearly be certain that are hard earned cash will go towards more power and not more smoke.

Common Electric Terms

Before establishing the relationships and concepts of basic electricity it is important to explain all the common terms that are used. Terms will be listed in order of the most simple or common to terms that are not as used as often. These terms may be used in the other pages. Battery – The battery …

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Measuring Electricity – Voltage, Current, Power

Being able to measure electrical values is a great way to confirm and check over your power system. This may be essential if you are building an RC model where you have chosen the power system gear. Keep in mind all electrical components worst enemy is heat. Making certain your motor, ESC, and LiPo batteries …

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