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Old Sep 02, 2011, 02:38 PM
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United Kingdom, England, Walthamstow
Joined Jun 2011
53 Posts
Help!
Alternative brushed motors for cheap stock 380's

Hello guy's.

I've recently got hold of really cheap racing boat called EP RACING BOAT "VICTORY" (costed me less than 25)

So painted the hull made it look nice as well replaced stock 7.2 1800mah NiMh with 11.1 5000mah lipo. Performance is great boat runs well exept. motors are melting down. So i have added two 6cm fans next each motor to cool them down. Still after runs temperature is too high. So the question is: what type of motors could i use instead of stock 380's. I would like them to bee able to handle 11.1 volts
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Old Sep 02, 2011, 02:58 PM
Registered User
United Kingdom, England, Walthamstow
Joined Jun 2011
53 Posts
HERE IS A VIDEO OF ONE OF THE RUNS

EP Racing Boat "Victory" after few modifications (1 min 59 sec)
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Old Sep 02, 2011, 03:07 PM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,087 Posts
Hi Mad,

The issue with your 380 running hot isn't really the higher Voltage (though I'd use smaller props to keep the temperature low(er)), but the increased runtime, which is about three times as long as with the stock 1800mAh.

The brushed motors have an efficiency of about 70% max, the rest of the electric energy is converted into heat.
Grab a 30W soldering iron and plug it in, you get an idea of the heat produced.

It 'll take more than a few fans to keep your motors cool, watercooling the can and adding brushtabcooling is the way to go if you want to keep the motors working.
Permanent overheating damages the magnets which will lose their power, ruining your motors.

This is the simplest version, a coil (not very efficient) and tubing soldered onto the connecting tabs:



If you want to add cooling coils, you'll have to alter the motormounts to make that possible, a bulkhead style mount like this gives you room for the coil, or a cooling jacket:



Make sure the slots on the front of the motor are not blocked by the motormount, the airflow through the armature is cruicial to the motor.

If you want a 'fancy', but highly efficient cooling, go for a jacket, like the one on this 700BB:



Regards, Jan.
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Old Sep 02, 2011, 03:29 PM
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United Kingdom, England, Walthamstow
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WCS is a great idea, but as you can see i am very limited in space in a boat, by which i mean motor mounts are really cramped
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Old Sep 03, 2011, 06:28 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,087 Posts
Hi Mad,

Hence my suggestion to make a new motormount, bulkhead style, which give you ample room for whatever type of cooling you have in mind.

Keep in mind, you're modifying a toy, which was never intended for great speeds or long runtimes, so you'll have to alter these things.

Regards, Jan.
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Old Sep 03, 2011, 12:44 PM
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Blackpool, Lancs
Joined Feb 2006
2,995 Posts
If the motors were really 6 volt types that the manufacturers fitted to get a performance boost by cutting into the safety margin, then adding an extra 50% will certainly take them well out of their comfort zone. There are speed 400s rated for the higher voltage, and, with shopping around, types with a winding intended for higher performance. The bearings and brushes might well withstand the higher RPM as well.
A smaller diameter prop will help - it will let the motor spin faster, and will push back a faster stream of water, and since every action has an equal and opposite reaction, will result in a higher forward speed.
Just having a fan to cool the motors will do nothing unless there is some way to let the hot air out, and replacement cool air in. If the boat flips, these air holes will show the other problem - the holes are a way in for water. This is the advantage of water cooling - cold water in from the outside world, hot water back out.
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Old Sep 04, 2011, 01:42 AM
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United States, CA, Orange County
Joined Aug 2011
2,158 Posts
Melting Motors

There are some 380/400 size motors designed for the small rc cars and trucks, that should work. Also use the correct speed control, as that can effect things to. The comment on trying to upgrade a toy is right on!
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Old Sep 04, 2011, 12:31 PM
Straight up is all I ask
Fairfield Ct USA
Joined Apr 2002
2,323 Posts
You look ready for brushless power never look back .
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