Left side drive: what's current?

[badgineer]

Regarding bolting the sprocket - personally, I do that to 6 bolt interface replacing the brake. Rear brake is a 'drag brake' anyway, and regen perfectly performs that function.

Yeah, the rear driven sprocket - my plan too: replace the disk brake.

But my concern is about attaching the little driving sprocket to motor shaft. What do you do on that end of the drivetrain?

Thanks for the info, also regarding CAD. Only once ever tried my hand at this area of design tbh, hence the child toy approach . Lack of time.

Br,

 

[badgineer]

deliberately obtuse without offering any merit or value.

Hi. If i'm obtuse and offer no valuable info, it's not deliberate. I'm trying the opposite!
Here my last honest attempt:
The motor you quoted (https://alienpowersystem.com/shop/b...ensored-outrunner-brushless-motor-30kv-2800w/) is specified with 7.5Nm of torque. You expect to get max power at 600 rpm (you said 1200 max, 1260 is the max kv * u).
Here a free calculator, so you can easily calculate what power you get at 7.5Nm and 600 rpm, if you don't trust the obtuse person from the internet (admittedly a good idea):
http://wentec.com/unipower/calculators/power_torque.asp

Spoiler alert.
It's 500W.

So the specs from the page contradict each other, if my math is not off.
I suspect it's the power rating that's not right.
That's all

Br,

 

[thepronghorn]

I can't concur with your thinking because I've actually done calculations rather than made an assumption.

I made the same calculations as you, based on the same assumption as you. Only to realize while the calculations were correct, the assumption was wrong...

The 30 KV APS 6374S is designed to operate at a much lower rpm so that the corresponding power, torque and efficiency curves will also be lower

--> this assumption. It is an assumption, and it's wrong.

Typically the low kV motor is the exact same motor as the 200+ kV version, just with more turns of thinner wire.

This is seriously off topic already (and the wrong forum section!), but...

After looking at RC motors with especially low KV ratings I always wondered what the penalty for this is.

The trade off is that you either have to raise the voltage to spin it up to the same speed as the motors faster "brothers" to get the same power, or just be content much lower power than the "rated one". Or get a bigger motor.


Make a separate thread for small rc motors with high kv, (in the right forum section) and we can go further into details. I'm quite interested in this topic also.

You never showed your work, so I doubt you did any calculations.

I already explained the trade off more precisely with the motor in question, and I dont keep tossing out different motor stats.

I'm very sorry that missed the concept I was trying to explain, tThe 30 KV APS 6374S is designed to operate at a much lower rpm so that the corresponding power, torque and efficiency curves will also be lower. Just like the higher KV motor, peak power comes at the half the no load speed. So in my application the peak power is attained at half the much lower no load speed, and the same for torque.

Again, sorry that you cannot grasp that this motor was selected based on it having the desired attributes and there is no need to select any other.

Feel free to start another thread. I'm blocking you because you're being deliberately obtuse without offering any merit or value. Bye now

The bold part is 0% true. The specs that Alien Power Systems has provided on their website are completely wrong. There is no way that any 6374 motor wound to only 30Kv can do 80A continuous for even a short time. The 2800W rating is going to require at least 200V of input before you have even a hope of sustaining that power since the windings can probably only take 10A or even less. The power that can be obtained from a 6374 motor whether it is from scorpion or alien or turnigy or maytech is well understood. It is NOT 2800W at 1200 rpm. You cannot just "reconfigure" the motor and get 5x torque output. Especially not for £85.

We are trying to help you. The vendor's specs are lies.

 

[BalorNG]

The bold part is 0% true. The specs that Alien Power Systems has provided on their website are completely wrong. There is no way that any 6374 motor wound to only 30Kv can do 80A continuous for even a short time. The 2800W rating is going to require at least 200V of input before you have even a hope of sustaining that power since the windings can probably only take 10A or even less. The power that can be obtained from a 6374 motor whether it is from scorpion or alien or turnigy or maytech is well understood. It is NOT 2800W at 1200 rpm. You cannot just "reconfigure" the motor and get 5x torque output. Especially not for £85.

We are trying to help you. The vendor's specs are lies.

Technically, it is possible - more/better magnets, the can on motors I have seems to be rather sparsely populated, but there is certainly a limit to that and it comes with proportionally higher no-load current of course.

 

[thepronghorn]

I think mayyybe 2x peak torque is possible with some significant changes to the motor, but anything beyond that is going to be quite difficult.

Putting "more/better magnets" will only increase torque so much. As you said, there are limits. These limits will arrive much sooner than even doubling the torque much less 5x. The stator iron will quickly saturate as you increase magnet strength. You can redo your stator to make the teeth and yoke thicker, but then you have less room for windings, so they will not be able to take the same amount of current.

 

[BalorNG]

I think mayyybe 2x peak torque is possible with some significant changes to the motor, but anything beyond that is going to be quite difficult.

Putting "more/better magnets" will only increase torque so much. As you said, there are limits. These limits will arrive much sooner than even doubling the torque much less 5x. The stator iron will quickly saturate as you increase magnet strength. You can redo your stator to make the teeth and yoke thicker, but then you have less room for windings, so they will not be able to take the same amount of current.

Yup, my point exactly.