I have a question about the rules for VRC Tipping Point this year. I am aware of rule R21, which states that, ¨No modifications to electronic components are allowed.¨ The question I have is this:
Does this rule account for modifying the plastic shell of the motor? My team has agreed many times that the plastic shell of the motor has extremely inefficient heat transfer, as there are no vents or heat sinks in the motor or motor casing. These little motors can create a lot of heat, and without proper heat transfer they overheat and stall out, causing many problems for my team. We are sure that our team is not alone in this struggle, and we are trying our best to solve it. Thank you for your time.
I would recommend being some keyboard cleaner or any other cool air spray. Spraying in between rounds will stop your motors from overheating. it that doesn’t solve it try adding less load to the motors.
It almost seems like you may be pushing these little motors outside of their comfort zones. Yes, these motors are capable of outputting a consistent power of 11W. But just because you can do something, does that mean you should?
After you’ve read those articles and you might understand a bit more about the 11W Smart Motor, consider the following.
The image below is a standard DC motor performance curve. As you can see max output power is further along the graph than max efficiency. When running at max efficiency, the motor will create the least amount of waste heat. But at max efficiency you aren’t getting the most power! That’s a bummer! So let’s crank it up to max power output. Notice how much less efficient a motor is at max output power?
Now let’s compare to an 11W Smart Motor performance curve I found. The engineers and programmers that designed this motor pulled off some voodoo to make using these motors easier for the masses. They basically made you have to worry about less! But unfortunately, here on Earth, we are limited by the laws of physics. So even though stall current and stall torque start off the same, they will eventually drop off. So they let you worry about less but you still have things to worry about.
You might want to try running your motors a bit more effeciently if you are trying to solve the overheating issue. You might want to ask yourself, “Do we really need this motor to run at max power?”
Or, you might just have to accept that if you want to push it to the limit, you’re going to create excess heat.
Just as a side note, this is not an issue with the V5 motors. This is an issue with every single electric motor in existence. No amount of ventilation or heat sinks will ever make a motor run the exact same all the way across it’s performance curve.
This is a GIANT PURPLE CLUE jumping up and down in front of you. If you look at the DC motor chart and the VEX V5 motor chart you can see there is a sweet spot at about 40-60% of the RPM of the motor. The programming team at VEX has worked on the controller programming so you don’t get to the bad end of the curve where stall currents become a factor.
Note that there are a number of different cartridges available and a pretty decent range of gears. (12, 24,36,48,60,72,84) that let you create the best gearing for your application. It makes me pretty sad when I see everything is direct drive, I know that in most cases it’s not the best case setup.
It’s a shame to get this deep into the season without really understanding what the gear choices are.
/sigh … so with all the disclaimers (not a drive, not a lift) not needing to be full power, what would be? A shooter? Same heat problem, maybe worse since it will run non stop the entire match. Claw motor? Full power to open, close, hold? Full power for 1/3 of a revolution?
Of course, every motor has these issues. The problem that I don’t understand about V5 smart motors is that they don’t have ventilation or heat sinks AT ALL. I have taken apart motors to swap gear cartridges, and have discovered that the motor casing is completely enclosed. At first we thought that the ridges on the sides were vents, but upon further investigation they are sealed. We often use Dust Off or electronic air dusters to try and cool our motors off, and we mistakenly thought that the air was flowing through the “vents” on the sides of the motor and cooling it off. Why is there no ventilation on these motors?