Quiet go kart motor

-andreas-

10 µW
Joined
Mar 20, 2021
Messages
6
Hi,
I have av Bafang BBS02 ebike, and I like how quiet it is. I am now building a go kart like thing. I would like it to be able to reverse, so because of that I look at just a motor with controller, since I would need a gearbox to be able to reverse with a BBS02, which seems complicated and heavy.
I already have 48V batteries, so would like to use those.
Looked at MY1020 motor kit, which is cheap, but it seems very loud. I have found a video of it connected to a sine wave controller:

https://m.youtube.com/watch?v=TRokp95aa90
It is more quiet, but not as quit as I would like on high RPM.
With a high speed motor without internal gears, the chain will also spin faster, which might also produce a louder sound? But I guess/hope that is marginal?
So, what motor/controller should I use to get it quiet?
 
The chain will make a racket; there's no getting around it. You won't be able to hear that little electronic noise over the chain. But if you use a brushless motor and sine wave controller, the motor itself should be pretty quiet. The larger the sprockets, the quieter the chain will be.

Belts can be quieter than chains, but aren't necessarily. The compression and suction of belt teeth meshing with a flanged sprocket can be quite loud.

With small diameter wheels, you need high RPM. That means plenty of transmission noise unless you use in-hub motors. The main reason the BBS02 can be so quiet is because it runs at low RPM.
 
GT3 belts are the quietest available. The smaller/narrower the chain the quieter. Running field orient control with a simulated sine wave esc is very quiet as well.

I have a similar goal of making a quiet drive. I think will add a small partial cover for the smallest pulley, and likely add some kind of thin foam inside to help dampen noise there.
 
You could consider serpentine as well if you can tension it consistently. A lot of early hybrids connected to the crankshaft with a serpentine belt and a strong tensioner. I think that's as quiet as a belt would get.
 
Chalo said:
The chain will make a racket; there's no getting around it. You won't be able to hear that little electronic noise over the chain. But if you use a brushless motor and sine wave controller, the motor itself should be pretty quiet. The larger the sprockets, the quieter the chain will be.
Thank you for the info! Then I see another problem with the high RPM on the MY1020 because that also means a small chainwheel at the motor side.
Chalo said:
Belts can be quieter than chains, but aren't necessarily. The compression and suction of belt teeth meshing with a flanged sprocket can be quite loud.
Belt is also an idea, thanks for your thoughts!
Chalo said:
With small diameter wheels, you need high RPM. That means plenty of transmission noise unless you use in-hub motors.
In this case actually the wheels will not be that small, the diameter will be about 45 cm. It will actually not go that fast either, 20-25km/h, the total max weight about 250kg. Probably a fast garden tractor is more what the actual build is, with motorcycle wheels…
But I have realized that the best would be to use a very low gear for the reverse, since it in the reverse state will be used at max 6km/h. That way I think that it in reverse could also be used to carry heavier loads of maybe 500kg(?) Not too steep hills.

Making it two geared and reverse the motor for going backwards would not be that much easier than make one forward gear and one backward, so maybe BBS02 will not be that much more complicated. But I will have to think about it.
Chalo said:
The main reason the BBS02 can be so quiet is because it runs at low RPM.
Good point! Do you think that a MY1020 at half the max RPM would have too low torque and also too low efficiency?

You seam experienced. Do you think that a 750W BBS02 would work with the high weights mentioned above if geared properly?
 
Hummina Shadeeba said:
GT3 belts are the quietest available.
But GT3 belts, are they not really tiny? Same size as GT2 used for 3d printers? I guess that I need a lot stronger than that? Good fact to know about GT3 belts though. Will probably then use them in some future project.
Hummina Shadeeba said:
The smaller/narrower the chain the quieter.
Ok, that is interesting.
Hummina Shadeeba said:
Running field orient control with a simulated sine wave esc is very quiet as well.
Is that an ordinary sine wave controller like KT controller, or do you speak about another type?
Hummina Shadeeba said:
I have a similar goal of making a quiet drive. I think will add a small partial cover for the smallest pulley, and likely add some kind of thin foam inside to help dampen noise there.
Interesting! That is a good thought to insulate the cover.
 
Jrbe said:
You could consider serpentine as well if you can tension it consistently. A lot of early hybrids connected to the crankshaft with a serpentine belt and a strong tensioner. I think that's as quiet as a belt would get.
Interesting, did not know of that type. Like several tiny V-belts into one.
 
Vesc speed controller runs a foc program. Cheap n small.

I’ve never seen a chart for serpentine belts; I don’t think they’re made for much torque, no?

The pulleys that will work with gt3 belts come in 3,5,8,12?mm pitch not just the 3mm u see with printers.
 
Hummina Shadeeba said:
I’ve never seen a chart for serpentine belts; I don’t think they’re made for much torque, no?

Hyundai, Kia, Buick, Ram, VW, and many others have used serpentine (poly v) belts to connect their motor / generator mild hybrids. They can handle a decent amount of torque with very good efficiency if they have a good tensioner. You can search design guides for them to see what they can handle.

You might be able to find pulleys in a junkyard from cars / trucks to use. Could source the tensioner there too.

The pulleys aren't too bad to make if you have access to a lathe.
 
For longest lasting, timing belts should be made of chains, the more rows the better.
Superiority reigns supreme in gear on gear action, think transfer case, chain is frowned upon in that world for strength.
I would never knowingly buy a vehicle with a non chain timing belt, nor give a second look to any vehicle with variable timing/cylinder shutoff.
I wouldnt be convinced on belt drive for availability xc or around the world, vs in the big city having fun, so whatever fits your budget. I have seen some chopper style motorcycles with big wide belt driving the rear wheel. Is that more for the looks then functionality, who knows
 
This isn't a tractor pull, this is a quiet go kart.
I do not see how timing the motor to the wheels is a requirement.
OP likely isn't planning a cross continental trip with it, that also wasn't part of the ask.
 
Theres no need for “timing” anything and timing belts are used to transfer torque from the driving to the driven pulley. They do a very efficient job of it and quieter than a chain.
 
For bicycles, I literally never hear the noise of the chain, the stuff I hear over the chain noise is the knobby tread tires of the e-mtb, the ratcheting of the rear freewheel I hear the noises of the motor using a cheap controller all the time over the chain and a bicycles chain is moveable, having a drive chain doesnt move, so the slack is gone.

If we are taking go karts, then what better example then motorcycles.

https://flbikers.com/belts-vs-drive-chains/

Drive Chains
Pros

First, chains are the most common drivetrain on the market because it’s the single most efficient way to transfer power from the engine to the back wheel. No other option can even compete when it comes to efficiency, since drive chains only create a 3% loss of power on average.
They’re strong and they’re durable. While we can have a discussion all day long about which is the better option on a street bike (drive chain or belt), when it comes to dirt bike there’s no competition. A chain is still the safest and best overall choice for any bike you plan on taking off the road and out onto the dirt.
They’re cost effective. It costs a heck of a lot less to not only produce a drive chain, but they’re also easier and cheaper to fix or even replace, and it’s possible for those with a little know-how to tackle the job of fixing or replacing the drive chain on their motorcycle themselves.

dirtbikemasters.com rusted chain.jpg

Cons

They’re high maintenance. You have to regularly clean and lube your drive chain so that it’s functioning optimally. You can’t get away with letting it sit too long without a proper cleaning. It’ll start to rust and you’ll increase your chances of having it snap while you’re out riding – which can be potentially fatal.
They’re loud. Compared to belts, a chain is significantly louder simply because of the material it’s made out of and the way the chain and the sprocket work together. Even a well-lubed chain isn’t going to be perfectly quiet.
Alignment is everything. If a bike has a drive chain, the back wheel needs to be perfectly aligned with the front otherwise it won’t roll onto and off the sprocket. If the alignment is off even by a little bit, the chain won’t function like it’s supposed to.



harley-davidsonforums.com damaged belt.jpg

Belts



Pros

They don’t require regular maintenance. You don’t have to constantly clean and lube your belt, because there’s no danger of it ever rusting. Belts are typically made of a strong synthetic material (such as Kevlar) and run completely clean. No upkeep means less work for you on a week-to-week basis.
They last longer. With absolutely zero maintenance on your part (and barring any freak accidents) a quality belt should last up to 20,000 miles without needing to be replaced. Kevlar belts typically last even longer.
They’re quieter. Because of the materials used to create the belt and sprocket set-up, you don’t get the same amount of noise from a belt system that you do with a traditional drive chain.



rideapart.com.jpg

Cons

They’re more expensive to produce and fix. Belts are significantly more expensive to produce than drive chains, and they’re more expensive to fix because it isn’t possible to “fix” a belt in the same way as a drive chain. If there’s anything wrong with a belt it typically needs to be completely replaced.
They lose more power. Unfortunately, belts aren’t as power efficient as drive chains. Whereas an average drive chain will only lose about 1-4% power during transmission, belts lose anywhere from 9-15%. That’s more than double a drive chain, and is a significant loss.
They’re more prone to damage. If anything gets caught in your belt, it can lead to irreparable damage. Even something as small as pebble will, over time, completely wear through the belt. And since it isn’t possible to do a quick fix on a belt, you’re looking at paying for an entire replacement if anything happens.

Hummina Shadeeba said:
Belts last longer than chains
 
From above:
“Chain is most efficient way to transfer power from the engine to the back wheel. No other option can even compete when it comes to efficiency, since drive chains only create a 3% loss of power on average.”
I don’t think this is true. I read belt is more efficient at anything but very low torque transfer.

Assuming ur pulleys don’t break (how long do they last and how can you tell they’re worn?) .. you bring an extra belt if you are going to do the trans-continental trip. Replacing a belt could be easier than a chain. Maybe bring two belts and still maybe lighter/easier than ur chain tool. Not that I even have a belt and know anything first hand.
 
They typically have a solid axle with bearings out near the wheels. The sprocket is typically in the middle making a master link in the chain a much simpler / faster install than taking it all apart.
Some do have the sprocket on the outside of all that stuff (or on one corner.) On these you might be able to just pick up that corner and replace the belt / chain.
 
Hillhater said:
It is a very poor design choice to put the axle sprocket outboard of the axle bearing.
Axle flex can cause chain tension fluctuations, wear, and sprocket skipping.

The axle doesn't flex or deflect in the middle from the load at the tires? At the bearings will have the least amount of deflection and likely the least amount of flex unless the bearings can pivot in their mounts. In that case it depends on where bearings are, where the sprocket is, spacing, how many bearings, etc.
 
Back
Top