# perm PMG 132 cooling issue



## arn0 (Aug 19, 2011)

Hi,

i have temperature issue in my engine compartment when the PMG 132 is running (on a boat, sorry ) but i am sure your experience could help a lot!

I wonder how to best cool that engine.
Has anyone tried watercooling ? (with a waterblock with thermal conduction on some metallic part, or any installation ?)
Or any kind of active cooling, with fan, on that engine ?
(I dont understand where to fit a fan...)

for info, engine is running @ 48V, i assume clockwise when going forward.

thank you very much for your kind advices!
Best,
Arnaud


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## kennybobby (Aug 10, 2012)

Do you have a picture of the engine compartment, maybe with some dimensions, etc. how much space is being heated, how much room is available for cooling equipment, etc.

For example, i've have seen motors cooled by looping copper tubing around the housing and then running water thru the line. Then you need a water pump, a heat exchanger and some way to chill the water.


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## arn0 (Aug 19, 2011)

Excellent thank you !

I had the exact same idea: pushing water in a copper coil around the motor, but was wondering few design points:

- is it more efficient to have the copper coil touching the motor, for best conduction ? (or should the copper coil run few cm away ?)
- is it a problem if the copper coil is partially covering the ventilation area of the motor ?
- would it be water condensation on the motor, and if yes is it risky ?

Big advantages with water cooling is that the boat is already pumping water for the diesel engine (it is a parallel hybrid configuration) so I think i could easily plug a 2nd pump on the water entry. And it runs quieter than a fan 
The coil would need to be drain in winter or filed with antifreeze.

The current dimension of the engine compartment is quite large (i would say 50cm x 50cm x 50 cm but i am actually thinking of reducing it to gain some space. So a compact watercooling could fit best.

Thanks again,
Arnaud


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## arn0 (Aug 19, 2011)

another naive point: is there a risk of excessive cooling of the stator (if it touches the copper coil) creating a too big temperature difference with the rotor ? (i think about potential dilation issues)


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## arn0 (Aug 19, 2011)

Sorry to think while i am writing... should the design use a small fan pushing the air on the copper coil, to send some fresh air on the stator ? Or convection is enough ?


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## arn0 (Aug 19, 2011)

I used a cheap copper coil I bought for another project (few $) it almost perfectly fit the PMG 132, attached are some pictures.

I can compact the loops in a smaller tube around the motor, but it would obstruct the venting areas.

the motor / copper-coil contact area is quite small, so i suspect the thermal conduction with be small. I hope the air will cool in contact to the copper coil 

Next step is to plug a small pump and put the boat in the water, do some tests to see check the engine room temperature and cooling water temperature, adjust the pump speed...

Before I go, do you have any reactions on that setup ?

Thanks,
Arnaud


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## kennybobby (Aug 10, 2012)

Thanks for posting the photos, that helps to see what you are trying to do.

i expected a long motor with more surface area for the stator so the cooling coils could made direct contact with the housing, but that pancake style motor is not going to have much area for contact. May have to reconsider how to get the heat out of that thing. Maybe Ripperton would have some ideas for you to consider, Dan is an expert on cooling systems for those type of motors.

It looks like you have some sort of gearbox on the motor to the prop shaft?


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## arn0 (Aug 19, 2011)

Thanks!

Yes, there is a gearbox, 1:1.8 reduction. It is actually not enough reduction (ideal would be 1:3) but that's another topic 
It is a poly-V belt drive to the propeller shaft.

My current controller (Bellman marine) has a 2 levels temperature control:
Temp >Temp1 starts a cooling fan
Temp >Temp2 lower the power to about 1kW.

I dont remember the values of Temp1 and Temp2, but I suspect Temp2 is around 80°C.

The temperature sensor is on the motor stator.

I am not satisfied with the cooling fan, which adds noise and push hot air on the passengers legs during summer...).

But alternatively to the watercooling solution maybe a fan fitted on the right spot (on the top of the motor ?), pumping the air into a tube, to some exhaust away from the passengers could work.

Anyone would know the natural airflow of the self-cooling fan inside the PMG 132 ?
ie: when turning CW looking from the shaft side, is it pumping air from the vents on the shaft side and blowing it on the pancake contour ?


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