Definitive Tests on the Heating and Cooling of Hub Motors

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Hummina Shadeeba
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Hummina Shadeeba » Feb 12, 2018 3:06 am

John in CR wrote:
Feb 11, 2018 4:45 am


Of course the easiest route to cooler temps (other than proper controller settings) remains the least used. That is directing more air flow toward the hubmotor shell.
or a bigger motor which will have a lower electrical resistance

John in CR
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by John in CR » Feb 12, 2018 8:10 am

Hummina Shadeeba wrote:
Feb 12, 2018 3:06 am
John in CR wrote:
Feb 11, 2018 4:45 am


Of course the easiest route to cooler temps (other than proper controller settings) remains the least used. That is directing more air flow toward the hubmotor shell.
or a bigger motor which will have a lower electrical resistance
Another easy way, though not as easy or cheap as air deflectors near the rear wheel. It doesn't necessarily have to be bigger though, just more efficient in the operating range required. My 14kg ventilated HubMonster slaughters the competition in the temperature department for moving 200kg or less at street and highway speeds. Of course I also use a non-typical controllers settings to run 28kw peak power input and stay cool even on mountain roads, ie 1.5:1 phase to battery current limit settings.

My much heavier 273 motor gets hotter just riding at 60mph or so even on flat roads, so bigger isn't always better in terms of heat.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Hummina Shadeeba » Feb 13, 2018 5:30 pm

Why would running such a motor amp to battery amp ratio be beneficial? Just reduced?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by eCue » Feb 13, 2018 6:38 pm

The motor vents need to be designed to pump air in on one side and pull air out on the other. Nothing a engineer couldn't figure out quickly. It would likely take me a day or two or more to figure so i'll leave it to those with the Computer programs and related skills :)
Solar charge station on wheels = distance not limited by the wall sockets :D

John in CR
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by John in CR » Feb 13, 2018 11:55 pm

Hummina Shadeeba wrote:
Feb 13, 2018 5:30 pm
Why would running such a motor amp to battery amp ratio be beneficial? Just reduced?
The typical high 2.5:1 Phase to Battery current limit ratio so commonly used is a main source of heat problems. The reason is because it too often creates high phase current when you don't want it, eg at lower speeds during ascents.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by John in CR » Feb 14, 2018 12:11 am

eCue wrote:
Feb 13, 2018 6:38 pm
The motor vents need to be designed to pump air in on one side and pull air out on the other. Nothing a engineer couldn't figure out quickly. It would likely take me a day or two or more to figure so i'll leave it to those with the Computer programs and related skills :)
Even optimized intake and exhaust hole shapes create very little air flow through a motor. The rpms are too low for such small effective blades to move much air. If you combine exhaust holes at the most extreme radius practical with exterior blades, then you can move alot of air except at very low speeds. I've used that approach of turning my motor sheel into a centrifugal fan for years with great results. I'd argue that it's the most effective quiet form of hubbie cooling, since I can make a 10 mile run generally uphill running at highway speeds 65-75mph pushing peak power input well above 20kw and arrive with a stator temp below 70°C. With 28kw peak power controller settings pushing a 400lb all up load I've only pushed the motor to my alarm temp setting twice in the past five years. Once was blasting up a continuous grade of 20% where I accelerated hard coming out of every switchback, and the other was running a 12 mile loop with 2 significant climbs riding as hard as I dared.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by eCue » Feb 14, 2018 12:50 am

John in CR wrote:
Feb 14, 2018 12:11 am
eCue wrote:
Feb 13, 2018 6:38 pm
The motor vents need to be designed to pump air in on one side and pull air out on the other. Nothing a engineer couldn't figure out quickly. It would likely take me a day or two or more to figure so i'll leave it to those with the Computer programs and related skills :)
Even optimized intake and exhaust hole shapes create very little air flow through a motor. The rpms are too low for such small effective blades to move much air. If you combine exhaust holes at the most extreme radius practical with exterior blades, then you can move alot of air except at very low speeds. I've used that approach of turning my motor sheel into a centrifugal fan for years with great results. I'd argue that it's the most effective quiet form of hubbie cooling, since I can make a 10 mile run generally uphill running at highway speeds 65-75mph pushing peak power input well above 20kw and arrive with a stator temp below 70°C. With 28kw peak power controller settings pushing a 400lb all up load I've only pushed the motor to my alarm temp setting twice in the past five years. Once was blasting up a continuous grade of 20% where I accelerated hard coming out of every switchback, and the other was running a 12 mile loop with 2 significant climbs riding as hard as I dared.

Good job you should team up with grin tech for a collaboration build / design :)

I say that as they could help you bring it into production and you could help them design a better motor case. Do you have a performance link on it ?

It likely can be tweaked further using a engineers computer program and 3d modelling.


Im liking the sounds of it
Solar charge station on wheels = distance not limited by the wall sockets :D

Hummina Shadeeba
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Hummina Shadeeba » Feb 14, 2018 2:26 am

John in CR wrote:
Feb 13, 2018 11:55 pm
Hummina Shadeeba wrote:
Feb 13, 2018 5:30 pm
Why would running such a motor amp to battery amp ratio be beneficial? Just reduced?
The typical high 2.5:1 Phase to Battery current limit ratio so commonly used is a main source of heat problems. The reason is because it too often creates high phase current when you don't want it, eg at lower speeds during ascents.
with your reduced ratio you reduce your low speed power potential with the rationale being its the most inefficient speed to be feeding big amps?

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