Should Thrusters be waterproofed

[Sky]

Hey everyone

I have 4 dc brushed motors to use as thrusters. Ive read though that it isnt necessary to waterproof dc motors for underwater use.
Each motor draws about 20amps
But can high current motor such as these still be used underwater without waterproofing?
Since apparently 2amps could already kill you so wouldnt 20 amps be very dangerous if used in water?
Could the amps somehow "escape" from the motor into the water and create a hazard?

And is it dangerous touching the motor leads directly if they have 12v 20amps flowing through them?

Thanks
Philipp

[ROV-Control]

I brushed should be waterproof under water. The motor will be damaged when running directly in fresh or saltwater. Brushless motors are the only ones which can be used directly in water.

[Sky]

Hey all
Just tested my thrusters, they create huge amount of thrust
One problem: at 5v they already draw 20amps each
Is there anything i can do to use a higher voltage , was planning on 12v and lowering the amps somehow?
(so higher voltage, low amps instead of low voltage, high amps)
So rather high voltage and low amps? How could i do this if it is possible
Because for 4 20amp thrusters,lights,camera ect I would need a BIG battery (too big...)
Thanks

[lwhistler]

"I brushed should be waterproof under water. The motor will be damaged when running directly in fresh or saltwater. Brushless motors are the only ones which can be used directly in water."

I have a RS-545 brushed motor that can run directly in fresh water, using a 12 volt car battery.



Leonard Whistler
http://www.hobbysubmarines.com

[SoakedinVancouver]

Hey all
Just tested my thrusters, they create huge amount of thrust
One problem: at 5v they already draw 20amps each
Is there anything i can do to use a higher voltage , was planning on 12v and lowering the amps somehow?
(so higher voltage, low amps instead of low voltage, high amps)
So rather high voltage and low amps? How could i do this if it is possible
Because for 4 20amp thrusters,lights,camera ect I would need a BIG battery (too big...)
Thanks

Check out "PWM motor control" on the 'Net, it will show you how to control your motors without wasting power (and needing MANY large batteries), and very smoothly too. The PWM principle works on incandescent lamps as well. LED lamp control is slightly different, and so is Halogen lamp control. How did you test your motors for thrust?

[SoakedinVancouver]

Hey everyone

I have 4 dc brushed motors to use as thrusters. Ive read though that it isnt necessary to waterproof dc motors for underwater use.
Each motor draws about 20amps
But can high current motor such as these still be used underwater without waterproofing?
Since apparently 2amps could already kill you so wouldnt 20 amps be very dangerous if used in water?
Could the amps somehow "escape" from the motor into the water and create a hazard? Electricity will "leak" into water, way more so in salt water than in fresh, but at 12 volts there is not much danger for you or the fish. You would only be wasting power. And accelerating corrosion in nearby metal parts. You do have to waterproof your motors, if only to have them last more than one dive.

And is it dangerous touching the motor leads directly if they have 12v 20amps flowing through them? Why would you want to do that? Electrically, not much danger of shock, unless you have an open wound and you are dipping the electrical junctions into it! But if the junction is not a good one, the joint might get hot enough to burn you. Maybe.

Thanks
Philipp

[ROV-Control]

lwhistler wrote:
I have a RS-545 brushed motor that can run directly in fresh water, using a 12 volt car battery.

Brushed motors run in fresh water. That's right, but normally they are air cooled. The motors intakes air to cool the coils. When running in freshwater the motor intakes the water and wash the fat and oil out of the bearings and the brushes will also be damaged. When you want to have fun a long time with motors the only way is to use brushless motors or you have very short service intervals.