Smaller Pulley = less heat + same range?

How-Tos & Esk8 mechanics
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#21

Could compare the wattage needed to go some same high speed with both upside down on the table and see how much the drivetrain is sucking

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#22

I would not use smaller than a 15T pulley on HTD5M, maybe 14T if needed but less seems to be asking for difficulties.

But yeah I feel like the smaller motor pulleys (above 14T on HTD5M) are going to be better for most people, except top speed. If you want top speed in lieu of more torque or range then you might be interested.

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#23

Doesn’t anyone use another tooth profile other than HTD? What about GT3? Seems quieter and more efficient and stronger

#24

With 25% fewer teeth on the motor pulley you’ll need 25% less motor current to maintain the same constant speed, say 20mph.

#25

If u don’t account for iron losses.

#26

And 25% more voltage, leaving power consumption the same. In a perfect world with 100% efficient motors.

Reality is your current drop will be less than 25%, but your voltage requirement will still be 25% more.

#27

25% less motor current so 43-44% less motor heat, so a bit less battery current as well, as the battery wattage will be roughly equal to the useful work plus the wasted heat, when switching from 16t to 12t.

#28

If u don’t account for iron losses.

if u want to run a motor as efficiently as possible (least heat and most range) and you like to accelerate hard or have hills, at top speed you’ll likely be best with more heat from iron losses (eddies) than copper resistance losses.

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#29

You are right about belt slip, i remember way less skipping with a 16T pulley under the same or higher belt tension.

Since i started using a motor mount with less center to center distance (385 instead of 435) the issue also got worse. The issue only occurs under breaking.

I recorded 60° C multiple times as the motor temp with the 12t.

I will test out 20T with a 395mm belt soon and post the result

#30

Side question: what is the use of 100A Motor and 50A Bat? Using a dual VESC wouldn’t it mean 100A (2x 50A) max draw from the Battery?

In other words: what is the benefit of 100A per motor if the Battery max current per side is 50A?

Or is the motor amps setting for both sides combined and the battery amps in VESC per side?

#31
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#32

I’ll go on record here saying you’re going to get shittier range with a smaller pulley going the exact same speed

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#33
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#34

xmatic hasn’t been working great for me since I put my xenith on 5.3, but I think if you’re on 5.1, it’s dead simple to change gear settings and set a max speed limit.

I’d set a top speed of 20mph and go for two exact same rides and then look at the wh/mile. Should be pretty simple to settle this debate.

#35

If green loctite (sorry, traveling so number is nit available) was not a thing I think plenty of us would test just to satisfy boredom. But having removed one set of pulleys out if necessity while setting off my smoke detectors (torch) I would rather not

#36

I’ve never recommended using Loctite on motor pulleys.

Once is enough.

#37

That’s not sufficient – the SOC should start the same and the hills be the same and the wind be the same.

#38

Yep, agree - start from full charge, do the same ride path, and do it on a day with no wind.

#39

and same temp motors and outside.

i gotta get logging and missing everything.

and stay in the same position, and that’s likely going to screw the comparison

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#40

Why not go 1:1 then? more top speed and more efficiency, according to your theory… then you’ll have a direct drive and we all know those are more efficient and put out less heat than geared, right? Why use a gear reduction at all if it just makes the board slower and less efficient? Perhaps its time everyone re-thinks their drivetrain to take advantage of the efficiency benefits of getting rid of gear reduction, if its true that reducing the gear reduction ratio improves efficiency.

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