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over heating

Old 12-27-2004, 04:28 AM
  #1  
Brans
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Default over heating

Hi Doc ! Compliments for the Season.

I need to know an answer or suggestion from you. The weekend I took the tug for a trial run. Everything went okay until after a 45 min test roaming our local pond. Things went a bit smoky.

The tug’s performance was great lots of thrust from that configuration I had. I recon it could pull a single seater canoe. The configuration I had was a 12v 20amp gel pack, speed 600 motor direct drive, 50amp esc, 3 cm prop 3 bladed. The tug weights about 4 kilograms and is 1.1m long.
Running the tug from 0 to full throttle the tug nearly wants to plain on the water.
I ran the tug slow for 5 mins on about 5% throttle. The usual messing around in the pond.

As I brought her back to me after 45 mins of running stop go the motor was smoking.
Was it because I was running
1. direct drive
2. no cooling on the motor
3. to much amperage
4. to much voltage.
5. prop size.
6. weight

I have know installed a cooling coil on another motor and a water pick that works great just behind the prop. The new motor is running a 2:1 gear box aswell with a bigger prop, should I use the 3cm prop or stay with the 5cm one.
I also installed a small Cpu fan rated 12v 0.08amps directly above the motor for extra cooling. Is this a better setup ?

Oh yes how do I know what the voltage of the motor is, can I test to see.

Thanking you Doc’

Brandon
Seasonal greetings from SA !!!!!!!
Old 12-27-2004, 04:51 AM
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pompebled
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Default RE: over heating

Hi Brandon,

I'm amazed that 600 motor lasted as long as it did, without cooling, a 30mm three-bladed prop, for that runtime is a bit much...

As I said in the other posting, a bigger motor (700) will have a much easier life in a tug your size.

But, the new set-up you described should work just fine (apart from the gear noise), you will probably find that the 30mm prop is a bit small, when geared down, but that's a matter of testing.
The cpu fan will most certainly help.

Regards, Jan.
Old 12-27-2004, 11:01 AM
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LtDoc
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Default RE: over heating

Brans,
I'm running late today but will think about your 'problem' at work....

"I have know installed a cooling coil on another motor and a water pick that works great just behind the prop. The new motor is running a 2:1 gear box aswell with a bigger prop, should I use the 3cm prop or stay with the 5cm one.
I also installed a small Cpu fan rated 12v 0.08amps directly above the motor for extra cooling. Is this a better setup ? "

The cooling coils and fan will definitely help. As to the size of prop, the 'best' way is to try one, see how it behaves, then try the other one. Whichever furnishes the required power without over heating is the one to use (no great science to that, huh?). So, if the new setup does what you want it to do without over heating, then it's a 'better' setup. Is it the 'best' that you can have? Probably not, there are quite a few different combinations that would probably yield the same results. The 'thing' is, if it does yield the required results, then it's certainly better than the original setup and ought to work just fine.

Now some of the 'options'.
The original set up with a smaller diameter of the same pitch as the original prop would result in less heating. It would also reduce the performance a bit, but since you seem to have more than you need to start with, that probably wouldn't be a big problem (maybe?). The same thing can be said for the same diameter prop with a finer pitch. Either way, the prop would be taking smaller 'swallows' of water per revolution, there would be less work envolved for the motor so it would run cooler.

Using a lesser voltage would also reduce the amount of work done by the motor, less speed, less torque, less heat. This isn't the 'best' option though, cuz' it envolves bigger or more extensive changes to the power train (different battery(s), ESC, etc.) and more expense. But, it is an option.

Go play with the new setup and see how it works with both size props. Something else that I would try is to 'plug' the cooling coils to see how the change in gearing affects the whole thing (not that I think you need to do away with the gearing OR the cooling coils, I'm just curious. And I'm always willing to let some one else do the work instead of me! - lol).
- 'Doc

[There's always more than one way of doing things. The 'best' way for YOU is the one that you have the ability and equipment to 'do' in the easiest manner.]

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