Electric motors are being claimed to be a workable and desirable replacement of combustion engines due to certain inherent advantages. All brands have launched a frantic race to launch electric motors and are making efforts to make the most significant technical advances in this sector.
There are often doubts about the suitability of using an electric motor over combustion engine. It is currently a topic of debate due to a sharp increase in oil prices. It is therefore important to know the fundamental advantages of using an electric motor over the current combustion engines.
1. The electric motors are much more interesting in terms of design, because they are compact and can be placed almost anywhere in the vehicle.
2. From the point of view of mechanical performance, it is much more convincing than the diesel or gasoline model. The principle is simple: a power source (battery) is connected to an electric motor via a controller and a converter which is used to enable supply of AC to the motor, thereby requiring less number of mechanical components and causing less wear and tear of those that are still required.
3. An electric motor also has the advantage of not having a significant friction loss, as is the case with a thermal combustion engine. In contrast, the energy is directly converted into motion almost in its entirety, leading to an immediate and constant acceleration.
4. Electric motors require less maintenance and do not need coolants or engine oil.
5. Virtually, they make no noise while in operation and produce negligible heat.
6. Vibrations are imperceptible as the engine does not suffer during operation.
7. An electric motor requires no gears except some mechanism to distinguish forward and backward movement, which may well be the reverse polarity of the motor itself.
8. The absence of a tank filled with fuel to power the engine through a pipe, gearbox and cooling apparatus induces the possibility of decentralizing the movement generation and placing multiple motors instead of one “central motor” coupled to a transmission. You only need some software to synchronize the different motors.
9. When it stops, it does not need any clutch to exert torque. It is also easy to recover braking energy (or a part of it) to recharge the batteries, because a motor and a generator are essentially the same.
10. Talking of fuel efficiency, an electric motor has an efficiency of around 90% which is the percentage of energy consumed in motion when the battery is usable, while a diesel engine, due to the thermodynamic limitations, has efficiency below 40%.
Moreover, this latest technology is environment friendly and cheaper than the existing combustion fuel driven engines.
The main issue with motors of this kind is not themselves as such, but their power sources – current battery technology being the weak point within the larger systems. Of course batteries are improving all the time, along with the means of charging them.
Given the growing ecological awareness of modern societies, people these days are more than happy to sacrifice few benefits of the combustion engines over electric ones. In fact it is prudent to make these sacrifices if we wish to have a cleaner and greener planet.
Ok, we all know the most popular mini RC out on the market is the Traxxas mini E-Revo and its chassis sharing cousins: The Rally, Slash and mini Summit. So what is the best way to power these mini machines? Do we use a NiMh battery, LiPo, and what about parallel and series systems? We will break this question down for our readers and give some answers!
So the mini E-Revo from Traxxas is an interesting chassis in that it can accept two batteries and run them either in parallel or series. Parallel connected batteries add MAH (capacity) for more run time while series connected battery packs add voltage for more power and speed. Whatever the choice, we must make sure that the two batteries are the same brand, type, and capacity. Another choice is to simply run one battery pack…..though due to the design of the chassis, many people feel that their RC car will run lop sided due to uneven weight distribution.
Traxxas warns that two 7.4V 2S Lipos should not be series connected as the voltage with be too high, and cause the Traxxas ESC to possibly overload. Traxxas does not warn against using two 6 cell NiMh packs in series….so that is a common configuration that speed hungry people run in their mini E-Revos. The brushless versions can run upwards of 50 mph in this configuration. Speed does not come without compromise; the ESC and the motor will get very hot……so may the battery packs if they are not the better high discharge type Nimh. Be careful running this type configuration, and give some time for everything to cool down. I recommend a 5 minute break for every 10 minute run.
To take advantage of the Lipo’s lower weight, many people find 3S 11.4V packs that fit the mini E-Revo and run them in parallel. Make sure that they will fit before buying…..there are so many different choices on the market. Get at least a 20C rated type to prevent overloading the battery packs. Like the Nimh battery packs….give a 5 minute break for every 10 minute run. Over heating the motor will cause the magnets to loose power and render the motor unrepairable and less able to put out its original output.
Parallel running two battery packs gives two advantages: longer run time and shared load. With two batteries in parallel the power draw is distributed between the two packs so that they don’t get over stressed. So a pair of 20C 1800 mah the effective batteries for trolling motor 7.4V Lipos connected in parallel would act and perform like a 40C 3600mah 7.4V Lipo.
Series running two battery packs gives the advantage of higher top speed, and acceleration because the voltage is doubled. Running in series, two 7.2V 1500 mah battery packs would act like one 14.4V 1500 mah battery. The disadvantage is higher amp draw from the motor which also will create heat for the ESC, battery, and motor. So choose this option carefully and understand that higher speeds come with higher wear and chance for damage to all the components involved with running higher voltage power.