Charge it up, drop it in, and go. This sums up the average racing or bashing session with an electric powered radio controlled vehicle. Outside of advanced modifications and maintenance, this is about all you'll have to do to enjoy an afternoon running your R/C.
Which is better, electric or nitro? This question is probably the most heated debate since Ford vs. Chevy. No matter which side of the argument you are on, both have their advantages or drawbacks. As mentioned many times in this article series, which you choose is going to boil down to your personal preference and what places you have available to run your R/C.
But it is notable to mention - as of the writing of this article, the top speed of any radio controlled vehicle, at over 110 miles per hour, is held by two electric vehicles.
How Electric R/C's Work
Electric-powered radio controlled vehicles require five basic components, some of which are shared with nitro powered vehicles:
- A battery pack
- A radio system, composed of a transmitter to send signals to the vehicle and a receiver to receive them
- A mechanical or electronic speed control to regulate accelleration
- An electric motor to power the vehicle
- A servo to control steering
If a manual speed control is used, a second servo is required to control the MSC and a second battery pack, usually made of four rechargeable AA sized batteries, is used to power the receiver and steering servo.
Battery Packs, Charger, and Discharger
Most electric R/C vehicles use a rechargeable nicad (nickel cadmium) or nimH (nickel metal-hydride) battery pack made of six 1.2 volt sub-C* cells connected in series to produce around 7.2 volts ranging from 1.5 to 3 amps (1500 to 3000 mah.)** The two main types currently used in radio controlled vehicles are nicads, (nickel-cadmium) and nimH (nickel-metal hydride) cells and both require discharging and maintenance for the longest life and punchiest charge. You can buy pre-made packs or individual cells and assemble the packs yourself. For extended information, visit the article on batteries and chargers.
Be sure the charger you buy is compatible with the type of packs you buy. Today's chargers "auto-peak" and have specific settings for charging rate and type of battery. It is important not to charge nimH packs on a nicad charger. Use only a charger that is designed for nimH charging or you will damage your expensive battery.
About Connectors
One of the points at which electrical current can be lost is at the various connectors that carry the power from the battery, through the ESC, and to the motor. One of the first things you should do when fitting a battery or any other main electrical component on an electric R/C is remove the Tamiya type connectors and replace them with one of the many low-resistance connectors available on the market. For more information, see the article on batteries and chargers.
Radio System
The receiver in an electric-powered R/C accepts the signals from the transmitter and sends throttle and steering instructions to the speed control and steering servo. It usually has three plug-in slots, one for the steering servo (channel 1,) one for the speed control (channel 2,) and one for the battery. The battery slot is only used when a mechanical speed control is installed in the vehicle or on a nitro powered R/C. If an ESC (electronic speed control) is installed, the main battery pack supplies power to the servo.
The servo plugs have three wires: a positve power lead, a negative power lead, and the radio signal lead. The power leads sent the voltage to the servo/speed control, and the signal tells it what to do. Different manufacturers place these in different positions on the plugs. For example:
| Brand | Wire 1 | Wire 2 | Wire 3 |
| Futaba | signal | positive | negative |
| Airtronics | positive | negative | signal |
Most of the connector plugs have tabs or one corner angled to avoid incorrect connection, but you can remove the leads from the plastic plug and put different plugs on them, or rearrange the plugs in the holes. This allows you to use servos and receivers of different brands as long as you arrange the leads accordingly. If you power up a receiver with the servo/speed control leads incorrectly connected, it can permanently damage the receiver!
Speed Control
There are two basic ways to regulate speed of your R/C, a mechanical speed control or an electronic speed control. Least expensive and often provided with kits is the mechanical speed control, which regulates the voltage sent to the motor by way of electrical resistors. More efficient and providing a smooth proportional transition from stop to full speed is the Electronic Speed control. Any model of vehicle will run faster, run longer, and have throttle response unparalleled by any MSC. Racing level ESC's do not have reverse, but a braking mechanism.
When selecting an ESC, be sure to select a model that will safely run the number of cells in the battery pack you plan to use and the turn of motor you plan on using. For more information on speed controls, see the RC-Resources article on electric powered speed controls.
Motor
The electric motors used in R/C are usually Yokomo 540 motors, designed to run with 7.2 volt 6-cell packs, but like everything else in this great hobby, can be customized and modified to the moon!
Like any DC electrical motors, R/C motors are made from two strong magnets around the inside of the "can," a composite three-segment iron armature core with copper brush windings, and graphite/metallic composite brushes held to the commutator with springs.
In order to make an informed decision on buying an electric motor, or an electric RC in which you'll run one, you'll want to gain a little understanding of how they work. You may want to view the article on electric motors which explores motor turns, winds, cleaning, brushes, and springs.
Cleaning and Maintenance
The arcing of the high amperage passing through the motor causes the comm to blacken and reduces conductivity, which decreases the overall power available to the motor. A regular comm cleaning, every couple of runs, is a low-cost way to keep your motors running well between comm turnings. See the article on electric motor maintenance for more information.
Motor Gearing
Power is sent from the motor to the wheels by way of a small pinion gear mounted directly on the motor, against a larger spur gear, and either directly to the axle in the case of lighter pan cars or through a step-down transmission for heavier vehicles. The pinion to spur gear ratio is a very important part of geting the most speed and performace out of your R/C. See the article on electric motors for more information.
Steering Servo
The steering servo is a miniature electric motor that rotates a splined shaft connected to the steering linkage, allowing the vehicle to turn to either side and back to center. Like many other R/C options, there are hundreds of different servos available and the speed, strength, and durability is proportionate to the cost. The steering servo you choose should be based on the type of vehicle you own, not whether you're putting it in an electric or nitro. Lighter vehicles, such as onroad cars or electric buggies, will do fine with most of the lower-cost average servos. A heavier vehicle, such as a stadium truck or monster truck, should run a high-torque servo, one with 89 oz/in. torque or better.
When selecting a steering servo, keep in mind that the power it receives is determined by the power source applied to the receiver. This affects the servo speed and torque. For example:
- 89 oz/in., .15 sec. 60° @ 4.8V
- 110 oz/in., .09 sec. 60° @ 6.0V
The higher the supplied voltage, the faster and stronger the servo will be. If you're running an electronic speed control, or a 4-cell AA receiver pack with a mechanical speed control, the voltage supplied to the servo will be 4.8 volts. If you're running an MSC with more than four cells in your servo pack, this will be determined by the voltage in the pack. You can speed up your servo by simply running a 5-cell pack (6 volts) if you plan on using a mechanical speed control. Some recievers come with a 6.0 voltage output too, a factor to keep in mind when selecting a receiver.
What You'll Need
In addition to the vehicle itself, a basic checklist for what you will need to own and operate an electric-powered radio controlled vehicle:
- Reliable electronics. If you opt for a kit as opposed to an RTR, choose the best electronic equipment you can afford, and the fastest servos available.
- Transmitter batteries. Use nicad or nimH rechargeables, and keep them in good shape. Transmitters require 8 AA sized batteries. If the radio system doesn't come with a charger, you'll need a method of charging these too.
- Electronic Speed Control. As above, if the RTR or kit didn't come with one, an ESC is going to be the best long-term investment you will make.
- Batteries, batteries, batteries. The battery pack and it's quality is the heart of electric R/C fun. Buy the best batteries you can afford, and build your own side-by-side packs if you can. Most likely you will want to own and maintain at least three good packs.
- Good discharger. For the reasons mentioned, battery maintenance and getting the best charge require a discharge after each run.
- Charger. Your battery charge is only going to be as good as your charger. Do some shopping and ask questions and find a charger that will last you a while and provide consistent results.
- Motors. It's a good idea to have several motors. Use older ones for practice, and save your good ones for racing.
- Comm cleaning brush and motor spray. As described, a good comm cleaning will provide longer run times, more available power, and make your motors last longer.
- Tools. Beyond the normal tool set for maintaining your R/C, a soldering iron and rosin core solder are used frequently. A turnbuckle wrinch is good to have for making suspension adjustments. Most importantly, a hardened tip pinion driver is very important to get the pinion gears good and tight.
- Low-resistance connectors. Replace the standard Tamiya-type connectors on your batteries, ESC, and motor with low-resistance connectors.
- Replacement brushes. Keep these handy and replace them when they begin to shorten or after every comm turn.
- Marvel Mystery Oil. Works great for lubricating bearings, motor bushings, and all other points of your R/C. If MMO is not available, any quality light grade lubricant is sufficient.
- Optional: commutator lathe. If you plan on sticking with the hobby for a while, investing in a comm lathe will allow you to recycle wearing motors and get the most out of them for racing.
- Optional: different pinion and spur sets. Expiramenting with gearing is critical for getting the most out of your electric powered R/C under various track conditions. Most racers have a full set of pinions from 12 to 26 tooth, and a few spur sizes to dial in the perfect gearing for any track conditions.
Bringing it All Together
As you can tell, there are hundreds of ways you can customize an electric vehicle for speed and performance, ony a few of which are touched on in this section of this article. Electric R/C vehicles are by no means short on technology, speed, or FUN!
If we were to boil it down to three things that make electric vehicles a good choice over nitro-powered vehicles:
- Quiet. Electrics make very little noise. If you live in an urban or suburban area, your neighbors are more likely to be annoyed by your hooting and hollering over the fun you're having than the RC itself.
- Affordability. While there's no doubt you can spend as much or more on the hobby with an electric, you can certainly get into it and stay in it for less if you start out wih electrics, as opposed to nitro.
- Cleaner. Let's face it: no fuel fumes, no drips, and you can keep it in your room. Although there are cleaners and other chemicals you may use in wrenching on your electric, you certainly don't have to worry about your wife or your mom telling you to get that stinky thing out of the house. Well, less chance of it, anyway.
And of course, there are a few drawbacks . . .
- Charge time. Depending on battery capacity, it can take from 15 to 30 minutes to charge a single pack. The higher the capacity, the longer it takes to charge.
- Run Time. Depending on the battery capacity, the weight of the vehicle, the motor and gearing you are using, and the speed control, run time can be from five minutes to 20 minutes, tops. With incorrect gearing and modified motors, expect lower run time. In this author's experience, run time is right around 1/4 the time it takes to charge.
- Battery Maintenance. Either you expend a lot of time with battery maintenance - discharging, cycling, and other conditioning - or you spend a lot of money on new batteries more often, but either way, the battery is the heart of the electric R/C and demands the most attention.
If any of the details here spark your interest, perhaps an electric powered vehicle is your style. But before you jump over to the Where to Buy listings, perhaps you should take a look at the adrenaline-pumping roar of nitro powered vehicles, the last section of this article.
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