Single motor drive

Hey guys, I’m trying a new thing and wondered if you had any ideas. Been working with a single motor drive for a 3-wheeled esk8. It uses an 80100 motor that can theoretically do 7000W. So it’s beast like. I drive with a chain and have a 20 tooth pinion on the motor and a 70 tooth on the sprocket. The esc is a VESC-tool compatible Flipsky controller capable of over 200 amps continuous (they say anyway). It actually runs better than any other esk8 I’ve ridden. More torque, faster speed, great handling. There’s just one problem, it appears to be overheating. When it’s cold, it gets to about 36 mph without any problems and it flies up steep hills no problem. But after running it at 3/4-full speed for about 2-3 miles it starts cutting power as though it hit the temperature limit. If I stop and wait for like a minute it starts right back up to full power, but then “overheats” soon thereafter. I feel the motor and I can wrap my hand around it and hold on indefinitely, it’s only like hot tub hotness. The vesc also feels rather cool. I used the vesc-tool many times to read the motor and reset it to what should be good settings. Maximum amperage I run it at the whole time is 60 battery amps. Motor amps are set to 120, but that is just to provide good startup torque. Temperature cutoff starts at 85 degC. Battery is a 12s6p Samsung 30Q. I really am having a hard time figuring out what could possibly be going on here. Any ideas?

What is the motor KV?

This is rolling the dice. Sometimes you win. Other times, you lose.

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The best way to figure it out is to connect a metr and log the telemetry information for later inspection.

It does sound like thermal throttling though.

Don’t ever trust ratings if they’re coming from the person who wants you to buy something.

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Always good to get video of the issue if you can’t sus it out.

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& the drive wheel diameter…

I guess the question I am asking is what is the maximum top speed this drive train can reach? Is it higher than you are looking to reach?

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Welcome to the forum. What’s your favorite size pulley?

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Thanks for all the responses, guys. The motor is 130 KV. I have a 10 inch diameter pneumatic rear/drive wheel. The motor pinion has 20 teeth and the wheel sprocket has 70 teeth, so a 3.5 gear ratio, right? By my calculations, to achieve the 35 mph I want I should need 4118 rpm at the motor shaft, which is about about 28,824 ERPM. The 12s6p battery, let’s say, is a nominal 44.4 V so it should be able to handle up to 5772 rpm and 40,404 ERPM, right? Assuming all those numbers are correct, my correct speed should be well below and in the safe zone, right? The battery, although it can handle more, is set by the bms to do no more than 60 amps. I have my vesc set to the same. I have actually tried a number of different vescs by Maytech and Flipsky and this vesc physically appears to be the highest quality one I’ve used yet. The motor is the same. Unfortunately, all of them continue to lead to this overheating problem. I definitely want to hook up a bluetooth metr or something to it. Good recommendations on that?

Your drive train is not setup for optimal performance at your desired top speed, your top speed is too high. This means that you are always working your motor too hard to achieve the speed you want. Excess top speed is generally a bad thing.

If you go to a 100 teeth wheel pulley you will make the load on the motor much less, so less heat, you will reach your desired top speed and have more torque.

If you cannot fit the 100teeth pulley on the 10inch wheel, you might consider using a smaller wheel. You still need more teeth on the wheel pulley though, 80teeth would be required for 8inch wheel.

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Wow, onloop. That is like the most productive information I have seen on this subject yet. I have been scratching my head over and over again trying to figure this out. Instead of increasing the wheel pulley I think I’ll just decrease the drive pinion. That should accomplish the same task right? Basically I’m looking for a gear ratio of 5, regardless of the way I accomplish it.

Two additional questions: first, where is this awesome calculator you are using? And second, does it matter that the motor can handle 7000W and you only have 3000W in there? I assume the 3000W just came from the battery maximum output, right?

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The esk8 calculator is an awesome tool, shout out to @3DServisas for his contribution

The rated wattage of your motors doesn’t really matter when doing these drive train design calculations. However, the bigger the motor and the higher the wattage rating the better

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Awesome. Thank you so much!

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So, I’ve still been working this single drive esk8 and it got better when I switched to a better gear ratio. Right now I have a 15T pinion and a 70T sprocket. However, after riding it in 80 degF weather for about 4 miles at full speed it overheats. I’m using a 80100 motor and it puts out major torque. I never draw more than 60 amps and usually no more than 40 amps while cruising. However it is definitely overheating. The motor is rated for maximum 7000W, so I figured down below 3000W continuous should be no biggie. It even appears to stay overheated if I’m just coasting down a hill with no throttle. I literally have to stop and let it cool down. Is there a possibility that the bearing is going bad? It kind of makes a chugging sound that indicates it’s not running like new anymore. All I want is a single motor drive that can go steady state and never overheat. What does it take to get it there?

These 80100 motors are just realllly inefficient. They run really hot no matter what. I think it’s a combination of losses from thick stator laminations, a large air gap between stator and magnets, and also low quality magnets. I believe they are also “made” for airplane applications where a propeller would push enough air to cool the motor. In our application the continuous power is 1-2000 watts tops

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Thanks for the response. I think you’re probably right about that. Any recommendations for a nice big motor like the 80100 that could handle longer runtimes?