Quote:
Originally Posted by ToddF
I'll take our shooter from last year as an example. We used a pair of RS-550 motors ($7.25 ea) driven by a pair of Jaguar drives ($119 ea), for a total of $252.50 system price.
That motor is 36mm in diameter, has a Kv of 1608 rpm/V, max current draw of 85A and max power of 254 Watts.
For an apples to apples comparison, Hobby King has a 36mm diameter brushless inrunner (S3674-1660) for $39.20 each. This motor has a Kv of 1660 rpm/V, a max current draw of 60A, and max power of 1600 Watts.
To drive it, we would need a 60A ESC. The HobbyKing Red Brick 60A ESC is $13.20 each. This ESC is a fraction of the size and weight of a jaguar, though it is controllable via PWM only.
So, using the motors and power drivers mandated by last years rules, we had a total of 508 Watts of power available at our shooter wheel for $252.50 total cost. If we were allowed to use brushless motor technology, we could have had 3200 Watts of power at our wheel for $104.80 total.
More power, less weight, less than half the cost. Note that the real driver of the cost difference is the drastically lower cost of the drive electronics. They can get that cost so low by removing all the smarts from the controller and making a bazillion of them. I wouldn't want to eliminate Jags and CIMS altogether, just allow these better technologies as an option for use where appropriate.
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Your comparison is completely unfair.
You are comparing US made versus Chinese made, you are also comparing an esc optimally sized for operation versus one far oversized for operation.
I love RC cars, and spend way too much money on hobbyking and can say with certainty I have used more motors and ESCs from them than anyone on chief. I love them for personal use, and a lot have surprised me with their performance and durability, but I would not put them on an FRC robot.