I am new to Electrathon, and starting a team this year. From my research, I see that most teams run with an ME-909 motor, but I'm wondering why. Is it price/efficiency, price/wattage, etc.?
I also do FRC, and have a couple extra CIM motors lying around, and I'm wondering if they're comparable to standard Electrathon motors.
I have also happened upon a bunch of Brushless electric steering assist motors from modern cars. However, I am unable to find good specs on them.
If anyone has any thoughts on brushed vs. brushless motors for Electrathon, I would love to hear them.
From what I found in the CIM motor it is 337 watts (767 watts per hp, I think)at max power which in Electrathon we don't run at that since it's not the most efficient. The Me-0909 no one uses in Tampa but I was thinking about getting it. It's stays are in ElectricMotorSports.com and runs 24-48v. In Tampa we have 4 motors. Me708, Me709 (I run this), the etek, and there are 2 cars with brushless hub motors. My schools sister team has one and have not been doing well. They also only run 40lbs of batteries 88ah.
Running the same motor, battery, controller combination as everyone else might help when you are just getting involved because other teams can help you solve problems and get you running. This also helps you sort out your chassis by allowing you to compare it to other teams.
That being said, I believe there is a great deal to be gained by running a brushless motor. Our Super Coupe runs an AC motor and has been very competitive.
The motor you list is a 12 volt motor with a maximum rating of 337 Watts. Lower voltage is less efficient than higher voltage. Most teams run 24 volts. We had great results with 48 volts in lead acid and have moved to 60 volts for Lithium.
A good battery pack should have a 1 hour capacity of between 600-1,000 Watt-hours. That means that the motor will need to run an adverage of 600-1,000 Watts. in other words, the motor should have a continuous rating of 600-1,000 Watts. if you are running on a tighter track where you must slow for the corner and accelerate out, the motor will benefit from a higher peak rating. We run our motor at around 4 times our average power, so around 4,000 Watts. This gives the driver excellent acceleration when needed.
It is just as important to have the right controller as the right motor. The two need to work well together. It is best if you find a motor controller combination that have been tested together. While many modern controllers are very adaptable, fiquire out the right setting for a new moter can be a nightmare.
There are brushless RC motors that weigh less than 1kg with a power of 5.2kw. I'd like to know why heavier brushed motor's weighing 8-15kg are preferred when much lighter and less expensive brush-less alternatives exist?
I believe the biggest reason larger sized motors are preferred is that the R/C brushless motors list peak ratings while the larger motors we traditionally use list continuous ratings. I have doubts that the R/C motors could last through an hour race without burning up.
The output cycles of RC motors don't line up very well for us either. RC tyres spin at a much faster speed than ours, so while they have good power, it's at a much faster shaft speed and lower torque than we desire. To use a traditional chain drive, you'd then need quite an array of gears to step-down the shaft speed to a useable velocity, so the weight benefit drops away, as does the efficiency.
On top of that, there's the problem of load cycling. The very small axle sizes don't like having sudden, large loads placed on them, and there's a fair difference between a ~3kg RC car and a 200kg fully-laden Electrathon car.
It could be done, but with great care for the motor and drivetrain packaging. Reduction of shock loads would be critical to ensure you get to the end of the race.
