PSA: Why small hub motors overheat and fail

ESK8 Electronics
61

The borderline racist comments I see on this forum really disgusts me. Heads up @evoheyax as far as I know majority of enertion products are made in china… China as a country has low income workforce and the infractstructure to support low cost manufacturing. Just because it says “Made in China” does not make it shit. Quite often the “chinese crap” you’ve spoken about is “crap” made by some westerner looking to make a quick buck.

As for efficiency, no watter what you do using a gearing system will always make a motor more efficient. That’s just how mechanics work. Perhaps if you find some magical law that changes how physics work you can let Car manufacturers know so that our vehicles can become cheaper, removing Diffs and Gear boxes for us!

4 Likes
62

^This ^this ^this

1 Like
63

I’m not saying china can’t produce good products. A lot of great products come from china. If you read any of my past comments about china producing stuff, you would know this.

My generalization here was about how these hubs are entering the market and being sold and tested as they stand today. The standards of every hub besides the 3 I have mentioned disgust me. If it’s a western behind some of these, maybe. But it’s not a racial thing. It’s a situational thing, an opportunity that the people who make the decisions about what products they should produce and sell see, and jump on, with little regard about making something feasible. They lie to your face, and say theres no heat issues, they will work great, and the first ride, they over heat and burn up. Seriously, tired of trying hubs from straight from manufactures in china and having this happen. It has nothing to do with race though. My point was that I can explain to why all of these motors are too small to be practical. They are not unpractical because they came from china, or because Chinese people made them, that’s just stupid. I live in liberal San Francisco for a reason man…

Look back to before in this thread, and you’ll see, cars and electric skateboards, while they have somethings in common, are nota good comparison.

Yes, gears are more efficient when you have many gears. But electric skateboards have one gear, not many. So they aren’t utilizing their full potential. Do you see cars with 1 gear? no.

Also, cars need a wider range of speed. The masses don’t need faster than 25 mph, and even a lot of speed freaks like me are content with 40 mph.

So not a good comparison…

64

I read the whole thread, no point replying otherwise. Whether it was a dig at china or not mate, you referenced “china” as the source of crap multiple times in just your first post alone. Could have left it at “small hub motors”.

As above. I read the whole thing. Perhaps you could do some learning about cars. Cars although moving much larger amounts with much larger engines are essentially doing the exact same thing as an eboard is mate. Just so you know if you were to remove a differential from a car and place a 1:1 gear in that you’d completely screw the efficiency of the motor and the vehicle itself, regardless of the fact it still has a 6 speed gearbox in it.

What’s efficiency to you? How much power is wasted vs how much output you get? Hub motors will ALWAYS have less either top speed or torque depending how you GEAR your belt/chain/sprocket driven motor. This is because you can either gear for top speed or torque. The only way around this is to gear within the hub itself, but then I guess it wouldn’t be a hub motor anymore.

I think you need to realise noone here arguing your facts has any problem with hubs, just your misinformation. Hubs have a place as done chain/belt etc. All with benefits all with disadvantages.

65

We will see how fast they go at the 2nd SPD… I’m guessing we will see 50+ Mph

not true, the primary objective in a patent is to prove you have some thing novel. Novel = New and a patent can have great value…

66

Tesla electric cars have single speed gearboxes

4 Likes
67

Talking about the thread either earlier this year or last year about china and correlation of china = crap in most peoples minds. What I was trying to do is give people perspective into why these manufactures do what they do. Cause the first thing people are going to say, is why do they make and sell something as a good product when it’s not?

Can you point me to my mis information? I’ll correct it right away

Again, cars aren’t a good comparison. Gearing does help in some ways, especially below 10 mph, but as @onloop said, it also has it’s bottle necks and weaknesses too. I also never said belts are bad. I agree they both have their place. But I think in time, hubs will win out, unless people start developing gear boxes for electric skateboards. Then, you can compare cars and electric skateboards. And then, hubs won’t be able to compete without a built in gear box also.

I don’t see this happening though, as now you need 2 gear boxes for a dual drive, synced together in such a way that they mechanical switch gears at exactly the same time. Also, how would you control this from your standard rc remote?

So until then, hubs are the future. Customers need to know though what they are getting, and most do not. You can blame the customer, but then, the customer assumes hubs are inherently bad, cause that’s what so many people say and will tell them. The reality, is they cheaped out and didn’t spend the money on a hub that actually works…

68

At the cost of some top speed and torque above 40 mph, yes. But not a single gas powered car has 1 gear only. And they are sacrificing efficiency by not having more gears. I think in the future, you’ll see them develop more gears into electric cars to get better range and torqure through out the range. Remember, like electric skateboards, these cars are all very new. So it’s easiest to start with 1 gear. In fact, tesla had 2 gears at first, but dropped one for simplicity, cause they couldn’t get the 2 working fast enough.

This is why tesla’s are beasts until about 40 mph, then all the super cars destroy it because they have gearing… Go watch the tesla racing channel on youtube and you’ll see what Im saying happen over and over again.

69

Actually I think it’s the opposite. Generally, everyone on the forums and internet have been led to believe that belt drives are inefficient and melt when they get wet. Also, if that were true, “China” wouldn’t have 200 different/same options available.

Reality -The boom in interest happened faster than good belt drives did. Most complaints about belt driven systems are true, but pertain to older versions that didn’t adjust well and rattled loose. Furthermore people couldn’t adjust anything properly on their own. So they gave up before they got it figured out.

Add in more misconceptions (problems that don’t exist) such as Belts stretch, Belts break when they get wet, Belts create drag…Only the last one is true IF it’s not set up correctly.

I’m not here bagging on Hubs. If you’ve fixed ride quality and ejection wheels you’re at the top of your game right next to Carvon.

My offer still stands if you want to see why I get so worked up when people bag on belt drives.

70

I might very well take you up on this offer. I wish as a community, we did more testing and less arguing.

This topic has turned in to a hubs vs belt drives again, when the topic was very clear. Why small hub motors have issues, and how they can be address to make better hub motors.

Did I add some flavor to it, yea, cause If I gave you a spread sheet with data, many would get lost or not fully see the picture I’m trying to paint in peoples heads. But I challange, anyone in this community, who thinks they have a small hub motor that won’t overheat, come to SF, try it on my route with my weight and riding style, and I’ll give you a pair new large hubs for free if they stay under 160 F the entire way. The real overall goal was to inform and share research and development with the community, so they can better understand why hubs up until now, couldn’t do what the belt drive counter part could, and make better purchasing decision. $250-$800 for small hubs that are too small, or $400-$600 for larger hubs that don’t have the same issues.

4 Likes
71

you need to clarify your claims in more detail… are you talking about using identical motors? or just in general?

We compared R1 vs R2 and documented the results, surprisingly the R2 is more efficient.

1 Like
72

OP, you seem to be very knowledgeable about hub motors and only recommends those three examples above. Another poster mentioned Meepo’s 90mm hub motor and his good experience with it, which I happen to share. Any specific reason other than it’s from China and inexpensive why you don’t think it’s worth mentioning about it? It doesn’t seem to suffer from over-heating, it runs great at 22mph, climbs a 20% hill. It’s been selling like hotcakes last couple months with many good experiences. If you are curious and want to take a look at it I have an extra slightly defective motor you are welcomed to take a look at. Where are you located? I’m near LA.

73

The torque curve of a combustion engine and a electric motor are very different. Electric don’t really need multiple gears. Think formula e does use transmissions though and some still choose single speed gearboxes. But my point is they are not using direct 1:1 drive.

1 Like
74

Yes @onloop because otherwise there’s no point comparing different implementations? If you took you hub motor you had made and slapped a bit of gearing on it, it would become more efficient, obviously at the cost of theoretical top speed though are you likely to ever hit that?

75

just not in terms of distance traveled over time… then it would be less efficient…

it would have fucking shite loads of torque potential though!.. however you might skip teeth on the belt, which is a loss of torque, which is also an inefficient use of torque… so less efficient…

Maybe edit your post & remove the word “ALWAYS” as its a bit misleading.

76

I haven’t tried these in particular. The reason is simply down to stator size. I’m not entirely sure what the size of the stator is, but the stator size will tell you how much iron you have in the core and the amount of copper you can fit in the motor. There is a certain size of stator, that becomes large enough, to were the motors don’t become saturated under any case. These small motors, simply can’t fit the amount of copper or iron (stator size) to run efficiently. Once you hit 160 F, motor efficiency goes down the tube. And these small motors will always struggle to stay cool under harsh riding.

Everything comes down to how long you ride for, how many hills you hit, your weight as a rider, and how you ride.

I never said you can’t have good results with these small hub motors, but that they have a lot of weakness, that will result in a shorter life of the motor specifically (possibly, very short, but best case, a fraction of what you should get from a motor). Unless you limit amp output to these little motors to control heat, but then, you won’t get performance anywheres close to a belt drive system. The goal is be able to compete with belt drive systems, and it’s physically impossible, in that little space, to fit enough stator (iron) and copper to make the motor be able to run the way we need it to compete with belt drives. Maybe meepo hub motors work, but they are very limited in the amps you can put into them, which limits torque. In addition, with the limited amount of copper and stator, they need even more amps to get the same torque as a larger motor.

For example: Before, I needed 4 amps to cruise at full speed on flat. Now, I need less than 2 amps to cruise at full speed on flat. Which is going to result in better range?

Now, you can say the meepo gets great range, so don’t they have great efficiency? That’s due to is lower top speed. 15 mph is the best speed for efficiency of most of these motors. 10 mph or less, and your not running efficiently with a hub motor. I like to ride at least 25 mph at all times. Over 20 mph, the wind resistance is exponential, and kills range. So this is why it takes 4 amps for me to cruise at top speed. At 15 mph, it goes back down to around 2 amps again on the old motors. On the new motors, Its about 1 amp to cruise at 15 mph. But I never ride like that. So I get shitty range. It’s not that my small motors are less efficient than meepos, just that I like to ride faster at all times than the meepo motors can even do, so my range takes a punch to the gut.

BTW: All of these numbers are per motor. System includes 4 motors.

At the end of the day, they can work, for certain people, but if your looking for reliability, durability, power, and better top speed, you simply can’t get that from a small motor due to the limitations I’ve outlined in this thread.

Maybe for you and some others, they will work, but it’s better to not be working your motors near their absolute potential. That will lead to issues.

3 Likes
77

How do you explain Koenigsegg decision to ditch the transmission in their Regera with the differential having a 2.73 final drive with a ratio?

http://1hosj01irnixn8onr1zmv5s1.wpengine.netdna-cdn.com/wp-content/uploads/2015/03/Illustration_Direct_Drive_20170525_07_lj-930x529.jpg

I understood how this propulsion system is possible.

1 Like
78

well unless you’re trying to skew results it will always be more efficient, obviously with something as powerful as those on the R2 you’d barely be gearing, something like a 2:3 would still be insane. if you were to use the same gearing you used on the R1 that would obviously be insanely stupid Distance traveled over time would be hard for anyone to prove without an apples to apples of actual riding

79

lol, you’ll always find a fringe case. I guess I should be more specific and say none of the big dogs in the car industry are doing it. Ford, Crysler, Dogde, Audi, Subaru, BMW, Toyota, Honda, Acura, None of them use a single gear in their combustion cars.

Now, thats a bit unfair also, since its a hybrid, not a solo combustion car.

But as @Titoxd10001 said, it is a bit unfair to compared combustion cars to electric cars in their torque curves, so I’ll leave it at that.

80

Well the regera has a torque converter which is kind of like a transmission and and it has multiple electric motors. It’s geared for like 250mph though lol