Water cooled or air cooled motor?

[Podbuilder]

Well I hope this works.  This seems to be the only place I can post a comment.   I do have a crazy project in mind and my user name does kind of give it away...  I do have some questions about motors and other parts that I hope can be answered in this forum.

Brad.

[Podbuilder]

Hello,  does the water cooled motor require an additional pump or is the pumping action performed inside the motor?

Brad.

[e-lmer]

Ask away Brad.

[Podbuilder]

Im interested in using the 10kw 48v system to drive a project I'm currently building, however I'm not sure if I should go water cooled or air cooled?  So, when would you use a water cooled motor over an air cooled and does the water cooled require an external pump?  If so, what capacity pump?  I would be running the water through a motor bike radiator for my project.

Thanks
Brad.

[Morgen 3Eman]

Hi Pod bulider,

I'm personally biased for water cooling systems.  If you Google thermo-sysphon cooling, you will find out about a system that needs no external pump. 

TTFN,
Dennis

[Podbuilder]

Excellent.  So a pump isn't required.  The heated water, steam heads off down the pipe to the radiator where it's cooled then cycles back into the motor again..  makes perfect sense.

So it's a water cool motor Im looking for.   

Cheers
Brad.

[Bikemad]

Hi Brad andto the forum.

I moved your posts to this section as I assumed you were referring to either a Qpod or some other form of electric pod vehicle:




If I have got this in the wrong section please let me know and I'll move it again.

If you are planning to use the high power for any length of time it might be better to go with liquid cooling to help dissipate the build up of heat.

I would use an external pump to ensure a continuous flow of coolant through the radiator in the correct direction (top to bottom) especially when the motor is working hard at low RPM and while running in the reverse direction.

I don't know what capacity pump you would need, but the flow rate will be limited by the internal size of the pipe unions on the motor, and also on the speed controller cooler if a liquid cooled controller is used.

Alan
 

[Podbuilder]

Not exactly a car.  I've added an avatar, a picture taken of me a few months back...as a clue.   

I've just read a ton of info on the input amps to get maximum output from the 10kw and 5kw motors Vs maximum output from batteries before they start to fry.  Higher voltage motors need lower amps  to get higher W output, but I've fairly limited space on the Pod to place batteries so I need to figure the best combination.   

I don't require a large battery capacity as it's not going to travel long distances, but I would like some power to have a little fun.  Any input would be appreciated...  yes, Im a little crazy, but my wife and kids still love me.   

Brad.

[Podbuilder]

The Pod's approximate weight with a 450cc motor is roughly 370kgs so I'd be assuming its going to be a little more with a load of batteries on board and another 100kg of rider... rounded up to 500kgs..  Would a 5kw motor be sufficient to accelerate with any speed and what's the maximum speed going to be on flat ground once the optimum gear ratio is set to get some acceleration?   Rear wheel diameter is 27" or 69cm across.  Lots of variables I know, but if a 5kw motor with 48v battery were used with a max 95A and continuous 60A. ...  would it work?? 

My brain has fried trying to work this out.


Brad.

[Morgen 3Eman]

Hi Pod,

Your reply mentioned "heat, steam heading down a pipe".   That is absolutely wrong.  For thermo-syphon to work, the hot water has to rise UP to the radiator, where it is cooled by transferring heat to the air , and  then, because it is now denser, falls back down to the motor where it absorbs more heat from the motor. 

However, since you have provided some detail about your project, I would recommend using not just a water pump, but a thermostatic cooling fan on the radiator as well.  My understanding is that your vehicle will be heavy and slow.  I think you are going to put a lot of amps (heat) into the motor for a small period of time to accelerate it, while some moderate amps will drawn during cruise.  That heat pulse should be dissipated as  quickly as possible to prevent heat damage to the motor.  Thermo-syphon wouldn't be the best choice.  If you do decide to try thermo-syphon before adding a water pump,  I would have a fan on the radiator. 



Are you trying to tell us you are building a bat mobile? 

TTFN,
Dennis

[Podbuilder]

 

Brad

[e-lmer]

The math seems pretty clear.
Can anyone spot any errors on this?

The equation for Watts is:
Power in Watts = J/s = kg * m^2 / t^3

You can factor this to
P = kg * ( m/t^2)  * ( m/t )
P = m * a * v

If we start with a 3kW motor and a 500kg vehicle:
    3kW = 500kg * (m/s^2) * m/s

With V=V0 = 0, you get a standing acceleration of
    3kW/500kg = 3/500 =  meters/second squared.
    = 6/500 * (39.37in/1meter) =   
That gives you about 0.5 inches/second/second.

That is an IDEAL calculation, a rule of thumb is 80% of that,
or .37 inches inches second squared.

With a 10kW motor you can look at about 1.2 fps^2, still not much.

You are talking about moving a half ton of vehicle.
For comparison my motorcycle is close to half of that.

for comparison, my 1kw e-bike is about 50, I am about 250, so 300lbs.
about 140kg/1000w = 1.4 m/s^2 ( * .80 )

That works out to about 2.4 fps^2.

[Podbuilder]

So I wont be spinning the back wheel.     That'll save rubber.

Brad.

[Morgen 3Eman]

Hi Pod,

Ok, I'm old and culturally ignorant:  WTF is that!

By the way, I know what a GeeBee racer looks like; do you?

TTFN
Dennis

[Podbuilder]

Google knows everything....   google Batpod.   Looks like a GeeBee racer is a little plane. 

Brad.