To water cool or not ?

This topic is empty.

Viewing 8 posts - 1 through 8 (of 8 total)

Author

Posts
23 March 2010 at 16:40 #26042
Sgt.Barnes
Participant
@sgt-barnes
Hi Guys
My first post so please be gentle

I’ am currently restoring an Aerokits Sea Commander. Previous large motor installs I have had have all been air cooled. E.g. my Perkasa ran an MFA marlin and wiperboard with the resistor out in the airflow. The motor was running marginally hot but nothing to worry about. I intend to use an 850 Torpedo and 50amp ESC with a 12v 7ah lead acid. I cannot seem to find a cooling coil for the motor commercially. I intend to water cool the ESC as it will be deep in the hull with no airflow, but do you think it is necessary to cool the motor at these ratings. I intend the boat to plane at scale speed but not go like a bat out of hell. If water cooling is the way forward are the 850 coils available or should I wind my own ? If winding my own will silicone pipe do the job or should I wind from copper or alloy tube for better heat transfer.
Many thanks for any help
Mark
Advert

23 March 2010 at 16:40 #5074
Sgt.Barnes
Participant
@sgt-barnes
23 March 2010 at 17:35 #26043
ashley needham
Participant
@ashleyneedham69188
Mark. My MFA Seahawk runs an 850 and gets moderately hot, the boat being a bit smaller internally than yours. The lad uses the boat and thus it spends most of its time at moderate to full throttle…..the motor wasnt getting too hot, but in order to avoid any fires….

I made my own water-cooling coils out of 1/4″ copper brake pipe, would around a cylinder I turned out of wood on a lathe to be slightly smaller than the motor so it would fit nice`n`tight, being a bit springy. I dont think silicone tube on its own would transfer sufficient heat to be worthwhile.

The only problem with this is you have to buy a coil of brake tubing, and i have enough left for a number of future projects!

I am not sure about alloy tube, i think you would be hard pressed to get stuff soft enough to bend without springs or messing about, and you do need a fair bit of tube (motor circumference x no of coils. i think I wound about 8 or so turns.

Ashley
23 March 2010 at 23:35 #26053
Telstar
Participant
@telstar
Hi Cornwall models can supply cooling coils for various diameter motors, including 48mm dia coil (I think thats the size of the 800 series motors) they also have water cooled flat plates to attach to ESC’s

http://www.cornwallmodelboats.co.uk

I think any overheating would kill the motor (burnout ) before you would have to send for the fire brigade

cheers Tom
24 March 2010 at 06:54 #26054
ashley needham
Participant
@ashleyneedham69188
Tom, you might think so….but on our pond I have seen smoke pouring from a boat, and when it came alongside the motor was very close to going, the back nylon part had melted and was smoking…!! you never know .

Ashley
24 March 2010 at 07:06 #26055
Paul T
Participant
@pault84577
Hi Mark and welcome to our little world.

On recent builds I have avoided water cooling and instead have fitted computer CPU cooling fans, they have very little current draw and have the advantage of continuing to cool the motors when the boat is still or moving at slow speed.

Paul
3 May 2010 at 17:16 #26651
shipmate60
Participant
@shipmate60
For better performance it is better to lighten her, the 12 volt 7AH battery is extremely heavy.

You could try a 12 volt 5 AH battery which is only just over 1/2 the weight or MiNim as these motors will take 14.2 volts quite readily.

Bob
3 May 2010 at 19:12 #26657
Ian Gardner
Participant
@iangardner62867
I have water cooled an 850 using copper tube bent round the motor casing and silicone tubing. I found it’s good bend the tubing to a smaller diameter than the casing thus ensuring a tight fit. The motor’s fine but now my ESC overheats a bit if running at less than full speed- I run on 14.4v ie 12 cells.

I agree that it would be far better to have MiMH cells- you can practically get up to 5Ah these days anyway. I never run my 4.3Ah cells down.

I think it should go well then.

Ian
Author

Posts