Motor cooling idea

[Olletj]

I am planning on getting the 5kw motor for my sailboat. Since I want to minimize the number of through holes, im thinking about how I can cool the motor. 
What do you guys think about using a liquid CPU cooler and connect it to the motor cooling pipes?

Something like this https://www.corsair.com/us/en/Categories/Products/Liquid-Cooling/iCUE-RGB-PRO-XT-Coolers/p/CW-9060045-WW.

Since the motor is 90% efficient there shouldnt be more than 500W of heat. In normal use even less, maybe 100-200W. I think the biggest CPU coolers can handle this. It will be similar to the radiator setup in a car. I still don't know where I would mount it thou.

[Bikemad]

Hi andto the forum.

Be aware that the motor efficiency can drop well below 90% under high current loads, and you should also consider the amount of unwanted heat that the controller will be producing due to its own inefficiencies.

The dynomometer figures for the 96V motor shows as little as 70% efficiency at ~123 Amps.
At this high current level, the input power is 11837 Watts and the output power is 8290 Watts, which would imply that 3547 Watts is presumably being wasted in the form of unwanted heat developing within the controller, the phase wires and the motor itself.
I don't suppose that a CPU cooler would be able to dissipate anywhere near that amount of heat. 

As your boat will be surrounded by a limitless supply of coolant, the obvious solution would be to use this water to cool the controller and motor, either directly if it's fresh water, or indirectly via a heat exchanger suitable for use with seawater.

Ideally, the controller should be mounted onto a suitable liquid cooled heatsink plate for optimum cooling:



Water to water cooling should have a much better heat transfer ability than water to air cooling.

Alan
 

[Olletj]

Hi and thanks for the remarks.

I see your point in using the water since its avalible but I don't think I need to. And I don't want more through holes and the complexity that a heat exchanger and pump brings if I can help it.

In that test they really pushed the motor. My application is in a sailboat and the max power will be around 5000W, which will only be used for short bursts while maneuvering. In this range the 48V version is 85% efficient. For continous use it will run at around 1000-2000W based on others experiences with similar boats. At this range its 90% efficient, which means 100-200W of heat. Any more than that will drain the batteries without a reasonable speed gain.

Also, I know several boats that uses the aircooled version in boats with success. The biggest CPU coolers will offer way more cooling than that.

The controller will be a VESC that I have used with only a cooling plate before with no high temperatures being recorded.

If I were to push the motor to its limit, then I think I would have to drill holes through the hull but for this application I don't think I have to.

I don't think direct cooling from the water will be practical. the cooling tubes on the motor are tiny and will clog up with weed. A heat exchanger would work, but thats expensive and more importantly, means more holes through the hull, which in my experience is a bad thing.