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I am working on an electric ATV project. I plan on building my own battery packs and converting this 500w ATV I bought into something much more capable. I am not super firmiliar with the motors, controllers and how they effect each other. I found a 3kw brushless motor that operates on 72v on Alibaba that has a planetary gear set on it so I can get the torque I want. So here is the question - If I were to attach a 5kw motor controller to the 3kw motor, would I be able to get 5kw of power out of it for short periods of time? Or is the limiting factor the resistance in the windings, and I would need a 5kw motor controller also at a higher voltage.
 

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What motor is it?

The power rating for motors is normally associated with a duty cycle and a specific ambient temperature. For industrial motors, this would be identified in the datasheet and would be quite an intensive duty cycle (e.g 24/7 with 30 celsius ambient, no airflow except what is generated by the motor itself), so the power rating would be quite conservative for an EV installation with intermittent duty cycles and plenty of cold airflow...

For cheap China-direct motors, the rating may be for very idealistic scenario, and may even be "rounded up" for marketing purposes.
 

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Discussion Starter #3
Here is the motor. https://m.alibaba.com/product/60759832294/60v-72v-1000w-1500w-3000W-BLDC.html?spm=a2706.wap_new_search.1998817009.31.6a7c284fUhnrqY

I just don't want to buy a 72v controller that will only give me 3kw of actual power.

I only need the additional power for short bursts (hill climbs).

https://m.aliexpress.com/item/32949376944.html?pid=808_0000_0109&spm=a2g0n.search-amp.list.32949376944&aff_trace_key=c2b3ab4242ac4cf0b13adb5ca265d513-1556637097719-05070-UneMJZVf&aff_platform=msite&m_page_id=7967amp-AVYM0yv5-q43oCqxbcKAqg1556637241839

If I go by ohms law, a 96v 5kw controller would push this motor a little when I need it

I am just not sure what the limiting factor is, the resistance/induction of the motor coils or the rating on the controller box.
 

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Given it's an Alibaba listing for a brand I've never heard of, I wouldn't try pushing that motor beyond the power they list.

There is nothing stopping you from using an overpowered controller and configuring its limits to match the motor specs. This would allow you to upgrade the motor later.
 

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Discussion Starter #5
Do you have any recommendations for a higher torque 5KW motor with some kind of gear reduction, or a motor that will allow for a planetary gear to be mounted on it? I need lots of torques but only about 1000RPM to 2000RPM speed.
 

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By "ATV", I'm guessing they stretch the intended Barbie Jeep application to fit into the category.

That Chinesium gearbox will likely get stripped if you double the motor torque and if you don't allow wheel slip.

Use two motors; they're cheap enough. Switch the second one in when you need it, or run both underrated most of the time, and Bob's your uncle.
 

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Try looking for scrapped off mobility scooters or electric wheelchairs - they come with very low gearing built in and are designed for high loads and long life
 
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