Statorade in large direct drive motor ?

Hi,

I'm thinking about buying the Silence S01 scooter : https://www.silence.eco/en/s01/
I have 50km ride to go to work, mainly on road, so I would like to be able to use it at max power for at least 30 to 40 km.
From feedback of existing users, it seems that the "sport mode" of the SO1 (max speed around 90-100 kph) is not sustainable for a long time due to overheating of the direct drive 7 kW motor.

--> Do you think Statorade could be usable in such a motor ? Is there any specific risks ?
Has someone already tried to use it in large DD motor (> 5 kW) on e-motorbikes ? What quantity have you used ?

While statorade should help cooling, any mods would invalidate your warranty. Another problem is that statorade will be far less effective on that scooter, because it results in better heat transfer outward through the magnets and magnetic backing ring to the outside air of a motor with spokes. On that scooter, the tire and air inside the hot tire is in the way of better heat transfer.

The bigger concern is that the motor overheats at higher cruising speed, which means it's not a good motor for the design (big battery for long range cruising at speed), because it's too inefficient...probably due to a very high slot and pole count combined with cheap stator steel. I have a big diameter (273mm) motor like that running a small diameter wheel, and it too ran hot running even light loads at steady cruise of 100kph. Find something better at cruising at high speed. With that company not being forthcoming with detail spec info, I wouldn't buy from them anyway. Either they don't have a good enough understanding, or they're hiding something.

Find something better to purchase.

by John in CR » Oct 16 2020 5:55am

While statorade should help cooling, any mods would invalidate your warranty. Another problem is that statorade will be far less effective on that scooter, because it results in better heat transfer outward through the magnets and magnetic backing ring to the outside air of a motor with spokes. On that scooter, the tire and air inside the hot tire is in the way of better heat transfer.

The bigger concern is that the motor overheats at higher cruising speed, which means it's not a good motor for the design (big battery for long range cruising at speed), because it's too inefficient...probably due to a very high slot and pole count combined with cheap stator steel. I have a big diameter (273mm) motor like that running a small diameter wheel, and it too ran hot running even light loads at steady cruise of 100kph. Find something better at cruising at high speed. With that company not being forthcoming with detail spec info, I wouldn't buy from them anyway. Either they don't have a good enough understanding, or they're hiding something.

Find something better to purchase.

Click to expand...

Is this where you get into liquid cooled motors?

ZeroEm said:

by John in CR » Oct 16 2020 5:55am

While statorade should help cooling, any mods would invalidate your warranty. Another problem is that statorade will be far less effective on that scooter, because it results in better heat transfer outward through the magnets and magnetic backing ring to the outside air of a motor with spokes. On that scooter, the tire and air inside the hot tire is in the way of better heat transfer.

The bigger concern is that the motor overheats at higher cruising speed, which means it's not a good motor for the design (big battery for long range cruising at speed), because it's too inefficient...probably due to a very high slot and pole count combined with cheap stator steel. I have a big diameter (273mm) motor like that running a small diameter wheel, and it too ran hot running even light loads at steady cruise of 100kph. Find something better at cruising at high speed. With that company not being forthcoming with detail spec info, I wouldn't buy from them anyway. Either they don't have a good enough understanding, or they're hiding something.

Find something better to purchase.

Click to expand...

Is this where you get into liquid cooled motors?

Click to expand...

Totally unnecessary for light EVs. Liquid cooling for heat created around 100°C is a silly prospect compared to liquid cooling related to cooling at the extreme temps surrounding the explosions in ICE.

My Leaf only cools the inverter not the motor. Think it is only a couple liters.
Was thinking that he wanted to stay at high speeds, you drive sorta fast. You don't have an issue with heat?

Fast scooters and motorcycles are best engineered with mid drives. Full fairings are good for limiting aero drag, but not letting much air flow reaching a rear hub. Statorade would give little cooling advantage if you can’t provide the motor with full air flow in the first place.

ZeroEm said:

My Leaf only cools the inverter not the motor. Think it is only a couple liters.
Was thinking that he wanted to stay at high speeds, you drive sorta fast. You don't have an issue with heat?

Click to expand...

Not at all except with the early QS v1 273 motor that has .5mm stator lams and a crazy high pole count, which is the motor I mentioned earlier. My HubMonsters are so efficient that I even running at 2000rpm doesn't cause heat issues. Lesser motors, especially high pole count hubbies, can have heat issues at even 1000rpm. Another example, but for mid-drives is the Israeli made Revolt motors. They use such crap laminating steel that everyone has heat issues with them even within their claimed rpm range.

Where this issue shows up in motor stats is in the no-load current. eg to spin a HubMonster up to 2krpm requires less than 3.5A, making about 350W of heat from hysteresis and eddy currents, which is easily dissipated with air flow of over 110mph. OTOH lots of hubbies will create too much heat to dissipate at half that speed even if coasting downhill, so there's no copper loss heat to dissipate.

I consider no-load current to be the most important spec to look at when trying to determine the quality of a motor, and even when it's not specifically spelled out you can often come up with a pretty good estimate when looking at motor test reports by dividing input power at the max rpm listed (where output torque is near 0) by the voltage at which the motor is tested.

by John in CR » Oct 16 2020 8:39pm

I consider no-load current to be the most important spec to look at when trying to determine the quality of a motor, and even when it's not specifically spelled out you can often come up with a pretty good estimate when looking at motor test reports by dividing input power at the max rpm listed (where output torque is near 0) by the voltage at which the motor is tested.

Click to expand...

Thank you for some incite, this will dominate my thinking for a while.

John in CR said:

I consider no-load current to be the most important spec to look at when trying to determine the quality of a motor, and even when it's not specifically spelled out you can often come up with a pretty good estimate when looking at motor test reports by dividing input power at the max rpm listed (where output torque is near 0) by the voltage at which the motor is tested.

Click to expand...

I've wondered about this, but have never seen it stated. I guess my question is whether the "spec" is only influenced by the motor, voltage and current, or if the results differ depending on whether the motor is driven by square, sine wave, or FOC commutation.

E-HP said:

John in CR said:

I consider no-load current to be the most important spec to look at when trying to determine the quality of a motor, and even when it's not specifically spelled out you can often come up with a pretty good estimate when looking at motor test reports by dividing input power at the max rpm listed (where output torque is near 0) by the voltage at which the motor is tested.

Click to expand...

I've wondered about this, but have never seen it stated. I guess my question is whether the "spec" is only influenced by the motor, voltage and current, or if the results differ depending on whether the motor is driven by square, sine wave, or FOC commutation.

Click to expand...

Voltage matters, since that determines rpm at WOT. Try to be sure you're making comparisons at the same rpm, or at least significant rpm with adjustments to estimate the no-load currents at the same rpm. You can be reasonably accurate with estimates, since the core losses increase with rpm in a generally linear manner. Just don't start with a measured no load current at a voltage at the lower end of a motor's rpm range. Also, don't compare that of a raw motor to one in a large spoked wheel with tire, especially a knobby tire, since the wind load can be quite large.

Regarding type of commutation, while it may make some difference, I doubt a large difference and it's likely to vary by motor too, since some have been designed such that the motor's output form is more trapezoidal shape to better match cheaper controllers. Interesting question though and I want to find out next time I have a raw motor set up to run in a vise. I have a couple of ReVolt motors I picked up super cheap, and don't know their Kv, so I need to run that test anyway, so I can determine at what voltage I can use them without heat issue.

Thank you for your advices