How are you realtime monitoring? Notebook in backpack or board suspended in air?
I never tried this with VESC tool, but I’ll look into it.
was just live data in vesc tool, but the vesc tool is far from accurate with such a small amount of current so its not worth comparing the current drawn without a load. A shame as it would tell so much.
Why do you think nobody’s been down this road? I’ve enjoyed the hell out of 12t motor pullies on my mountainboard since 2019.
I’ve run nothing but 72t wheel pullies, with 7, 8, 9 and 9.5in tires. I’ve run 12t, 14t, 15t, 16t… Never anything larger. When I first tried 12t pullies, I ran single idlers (power side only) on LONG ATC (all terrain creations) motor plates. Even with 2x stacked 608s forming each idler, I ate idler bearings like candy. I got extremely lucky in that 455mm belts worked perfectly with NO idlers on these mounts. Despite the small number of teeth engaged, I only get a tiny bit of slippage under max braking just before coming to a complete stop, ONLY when my belts are already on their last legs, or a bit loose. I’ve never had any slippage under power.
As for efficiency, torque, heat, range: The same rules re changing final drive ratio on a car apply to us. Marginally increasing the gear ratio (higher numeric ratio, more gear reduction) improves acceleration (and the power of regen braking) at the expense of efficiency/range. Since the motor is not working as hard to maintain your desired speed (thanks to more help from reduction) it should not run as hot. BUT, in practice, I tend to hoon more when I have some torque to play with, get everything a bit hotter than when I ran with larger motor pulleys.
IF, and only if, you can achieve perfect belt tension and have nice long motor plates, you SHOULD try 12t pullies (steel, from Hoyt St if you have 8mm keyed shafts… Mine have lasted 2000++ miles) The torque they provide for trail riding is nuts. With both on 12S w/ 190kv motors, I have just as much fun hooning on my 6374 powered mountainboard w/ 12/72 setup as I do on my Flux w/ 14/72 setup + MUCH more powerful 6380 motors. (4000W vs 3250W, run at 65A and 80A respectively)
If your motor plates are short, (belt under 400mm long) you may have more trouble with belt slippage, this won’t be worthwhile.
Alternatively, if you want to experiment with more reduction, can’t make 12t motor pullies work, someone posted a set of 72t sleeves that are pounded over your wheel pullies, present 76t, 80t, 83t, 87t, 90t around the outer perimeter… Belt teeth on the inside, gear teeth on the outside. You’re still limited by the max center-center distance of your motor plates, but this opens the door to much more recduction if you want to tackle trails, get temps down a bit. - SDP/SI eStore
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I have this hall meter thingy. Only used it for monitoring remaining Battery power. Maybe this unit could tell us more…
What would be the no-load experiments you are interested in? Is an averaged result in Wh even of any use or are we only interested in real time (recordable) data?
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I should get one of those. Wonder how it will do around all 3 phase wires or maybe u can just do one and extrapolate
The goal is to see how much current/power it takes to go some rpm or erpm revealing all the iron losses and mechanical losses. Could do it with a belt on and off. If u do a couple of speeds could … extrapolate and graph the exponentially growing Eddy currents and what gear ratio is most efficient for a certain power output.
OP wanted to know how his setup would perform moving to 12t from 16t, in terms of range and motor heat. It’s impossible for you to tell him with how this will affect his range because you don’t know the efficiency map for his motors or his riding style.
You say you’ve extensively ridden 12t motor pulleys. Have you extensively ridden larger motor pulleys? What did you see in terms of range when you switched?
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Well it’s incredibly simple and has been way over complicated after reading above
If you maintain the same speed 16 teeth would be 25% slower RPM for the motor so less efficiency most of the time.(there’s always a few exceptions to any blanket statements made like this)
As for gearing place the largest pully on you wheel you can that still gives you enough ground clearance then calculate the max speed you want to go and chose a suitable motor pully for that. I use 12t with 12mm belts it works fine on thane. Belt width has more of a impact than 12vs14 tooth with slip
As a general rule 6 teeth engagement is needed
Where: D = pitch diameter, large sprocket, inches
d = pitch diameter, small sprocket, inches
C = center distance between shafts, inches
Ng = number of grooves in small sprocket
PMDC motors are brushed DC motors with permanent magnets. We use BLDC motors which are brushless DC motors and are a lot more complicated.
This all just comes down to copper losses vs iron losses. The highest efficiency is when the two are equal during the period of the ride. So the only thing that matters is balancing out the copper and iron losses. Many motors we use suffer from high idle currents and thus high iron losses. In some of the worse ones spinning them fast can actually produce about the same amount of heat as pumping 70-80A into them.
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In my experience most of my battry is used acalarating. i don’t realy hold speed for very long at all. so higher gear ratios broth help with heat but I do modify the ramp speed to maintain traction proberbly having a large factor in that.
Adding to that, any motor that use an additional support bearing on the rotor, specially if that bearing is of the 2RS variant (rubber sealed on both sides), has a lot of additional speed dependent losses that can be somewhere between 50 W and 100 W, or even more if the manufacturer did a poor job of installing this bearing and it ends up misaligned, seem that more often than what is acceptable
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You can show me all the math, logic, and theoretical performance of random motors in the world, and how things should behave…
You need to run the test and see how things actually turn out in the real world. Lacroix claims using a larger motor pulley will get you more range on their boards. Who am I to argue - I haven’t tested it.
How about the hundreds of motor efficiency charts online with the motors been lest efficient at low rpm or high loads.
You also mentioned lacriox witch are mainly mountinboard base not Thane that I mention above giving you larger wheel pullys and there for a higher gear ratio. Also ignoring what I’ve said above about trying to maintain a 6 tooth pully engagement with the formuler engeners use included. any less and you should be duducting 20% of the power it can transmit per tooth less. Let’s call you out on your facts and charts and maths and real word experience.
You are also ignoring the fact in real life most of the consumption is used when taking off not many people go on long continues straights useing large ampage fighting huge wind drag. There’s a reasion most manufacture boards only go just over 20mph. It’s the same reasion most people don’t lean past 20deg on turns. This is proven by the low thermal heat soak of our ESC that are comely used. You need your efficiency to be were the most battry consumption is used not based on time or max speed or peek performance. If you go deeper in to it our motors are way over sized to be efficient because most of us like the extra power to launch us forwards past other with big smiles. just shows you how we use our boards by what parts are most comenly used…
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I’m more interested in seeing someone do a real world comparison and actually run the test to see which motor pulley results in better wh/mile.
Everything else has been argued ad nauseum on this forum, but to my knowledge nobody has done the experiment.
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You have to do the math with logs, and run every single data point and integrate everything to get meaningful data
I think I have a matlab script that does just that that I used on my final thesis to calculate and compare the efficiency of a hub motor if I were to make it and ride it
If you just take a random point in a efficiency graph it’s meaningless
On bigger motors, you usually have more range with a bigger pulley due to the huge rpm dependent losses they have, unless you ride fast that takes advantage of the higher average power
As a data point, my board went through various drivetrains
But these two bellow I got the same efficiency
- dual 6355 190Kv - 72/12 = 6.0 gear ratio and 8” tires
- dual 63100 140 Kv - 59/14 = 4.21 gear ratio and 9” tires
Both always between 14 and 15 Wh/km on both
Keep in mind that this only true for the way I ride and would be different for someone of different weight and different riding style
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This, combined with riding environment, likely cause massive differences in results.
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Yep, I have a dream of integrating into a app a tool that analyzes all your previous rides and calculates the optimal gearing for you and your riding style
Can expand that for a bunch of motors also taking all specs into consideration, including a thermal model to calculate the temperature profile and avoid suggesting something that will overheat
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This would be so clutch, especially if it integrated with something like metr
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I just returned to this after 2 weeks, sorry to post and bail. I have switched between 16t, 14t, 12t on the same board, and efficiency gets progressively worse as I drop tooth count. It’s been so long since I’ve run anything but 12t on this particular board, I can’t really quantify. I also have no way of separating the effect of limitless torque on my skating style… Absolute power corrupts absolutely. I skate much more aggressively with shorter (higher numeric ratio) gearing due to pulley swaps or smaller tire diameter. Your comment re his style + torque curve of his motor is a bit off… While the numbers may be different for his motors vs mine, the shape of the curve is the same for ALL of these motors which share a common 14-pole design. As for style, no matter what it is now, it won’t be the same with a different gear ratio 
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