Can this motor run in water?

[Clyd3]

well i'm the kinda stupid dude to go and mess up a decent motor in the pool, so yeah, I'll have to agree with chemelec... was amazed for a few days... but batteries appeared to be getting low (not really) and eventually motor siezed up. I got it around here somewhere, and you got me looking for it...

 

[heathtech]

That picture spooks me every time I see it!

 

[audioguru]

Many submersable pumps (for aquariums) don't have an electric motor. They have a diaphragm vibrating at the mains frequency and the thrust of their water "jet" is nearly nothing.
You don't want to have mains in a bathtub.

 

[heathtech]

Audioguru said...

Many submersable pumps (for aquariums) don't have an electric motor.....You don't want to have mains in a bathtub

I was actually refering to the garden/atrium fountain type pump, (you know, Cherub tinkling into pool) Some of them are battery powered or solar powered.

 

[stevez]

I understand that windage is a term used to describe the friction loss of the rotor due to the resistance air presents to the rotation. While it may not seem like much it's actually a consideration. Replacing the air with water will profoundly impact that - so much so that I would not expect a small DC motor to turn very fast at all - as compared to a dry condition.

As has already been noted - motors and pumps are made to be submersible so it has been done. Note that the cooling of the motor can become an issue. While the motor itself might be submerged, if there isn't an adequate pathway for the internal heat to get to the exterior then the motor might not last long.

 

[Styx]

you made a point there stevez,

with the increase in windage, the machine iwll actually take more current to get over the extra torque, thus it will get hotter quicker.

 

[evandude]

I've taken one of those garden fountain water pumps apart (it was used in my computer water cooling system) and it's a brushless design. The rotor consists of a big magnet with a plastic impeller attached, with a hole down through the middle of both... that whole assembly rode on a thin steel rod which was suspended at each end by little rubber knobs that went into sockets on each end. So, no bearings, the thing just spun on the metal rod... and none of the electrics were in the water, they were just sealed away in the plastic body.

 

[Dean Huster]

I'll repeat again - WATER IS EXTREMELY DISTRUCTIVE TO ELECTRONICS AND ELECTRICS

My point was to react to a statement that was putting water into the same category as nitric and sulfuric acid with regard to electronics. As you'll note in my post, water is fine and non-destructive when used on electronics in proper cleaning procedures. And I followed that up with the paragraph detailing the problems of non-proper water use -- aka, unintended water damage.

There are some uninformed folks out there that think if a bit of water is splashed on a radio, it'll explode and take out several people with it, a myth probably ingrained from watching too many inaccurate films or television programs.

Regarding the motors retaining water in the cleaning procedure, they will if not blown out and dried properly. Then all we did was give the bearings a good shot of oil and all was OK.

The examples of leaking washers and such are not a testament to the extreme destructive capabilities of water, but the long-term effects of water damage. A water leak at the eave of your roof that's quickly repaired does little, if any, damage.

All of the submersible pumps I've seen all have a water-sealed motor. All the electric model boats I've seen have the motor inboard and the propeller shaft running through either a lubricated "O"-ring or a grease-filled tube. Either method adds just a bit of friction to the system.

Dean

 

[Nigel Goodwin]

I'll repeat again - WATER IS EXTREMELY DISTRUCTIVE TO ELECTRONICS AND ELECTRICS

My point was to react to a statement that was putting water into the same category as nitric and sulfuric acid with regard to electronics. As you'll note in my post, water is fine and non-destructive when used on electronics in proper cleaning procedures.

Yes, but only under extremely carefully controlled conditions.

As for the reference to 'nitric and sulfuric acid', it's water that is known as 'the universal solvent', and not either of those two

 

[Dean Huster]

Yes, water will dissolve more materials than any other solvent. Lucky for me, or I'd smell like who knows what!

That is a compatibility issue. I can bathe in a tub of water for hours and it'll do me good, other than wrinkling the crap out of my fingers and toes. Bathe in a tub of sulfuric acid and I might be in a bit of trouble. But too much of a good thing .... if that same water bath lasts for days (especially if wearing "conacreta" shoes), that's another issue altogether.

Just stick the motor in the hull, drive a pump and make a jet boat out of the thing.

Dean

 

[zachtheterrible]

A pump that pumps water ina pond or pool is gna probably be too big for a small boat.

 

[rvk2]

ok guys, so now I'm working on my project, it involves creating turbulence in water.....how can I do that with electric motors? Let's say I have a metal tank, and I want to just splish-splash the water in there...can I do that with a submerged motor? Someone in this thread said that motors that are in water run much slower, which I can imagine. And if it does do that, I can't really get the turbulent flow going.
Also, if my motor is insulated and submerged in water, wouldn't the heat kill it since there's no room for the air to escape? Man its gonna be tough to sleep tonite with all these thoughts.

 

[Glyph]

Ok this is only a SUGGESTION, not the best way of doing things or the most professional but its quick, dirty and well within the means of most hobbyists.... (namely ME).

If the boat is big enough you can attack a strong magnet to the end of the motor (make sure its balanced or it'll vibrate like crazy) and put it close to hull of the boat. On the outside of the boat attach another magnet (or even a piece of stainless steel) to a shaft of some sort attached to the hull (this one must be balanced as well or the vibrations will rattle the boat).

The motor will get going inside the boat and transfer its motion magnetically to the outside of the boat.

For "Kid Proofing" both magnetics should be encased in plastic or something strong, magnets by themselves shatter easily.

I used this magnet method as a cool "Tornado in a bottle" desktop decoration for my room. Basically a jar with a spinning magnet in the bottle to keep the water vortexing.

Some people will say that the magnet will interfere with the motor and this is true. Although personally i haven't noticed any major declines in performance.

The submersible pumps using the BLDC motor and such will probably work better, but i haven't seen anything that runs on a voltage that's less than 12V. And when it comes to kid's toys ya don't want something too big/heavy/complicated/expensive. I find kids are more dangerous and damaging to equipment than guns/bombs/serial killers.

Although if you're just looking something that'll entertain the kid then maybe you don't even need motion outside the boat. Just attach a decent weight (decent as in 25-50% mass of the motor itself) off-balance to the motor shaft and house it inside the hull. When it turns on the boat will vibrate and dance around just due to the inertia. No need for outside motion.

 

[Phideaux]

The Motor Will run Fine Under Water. Well For a Little while, till it Rusts and seizes up. Probably a Few Days.

zachtheterrible, Even though water has a Relatively Low Resistance Because of Impurities, It is Still a relatively High Resistance to a Very Low Voltge, such as 3 volts.

Trolling motors used by many fishermen prove you are correct. Corrosion of bearings will eventually seize the motor, which in turn, will fry the windings. This, of course, only applies to DC motors.

 

[ante]

When I played with RC cars many years ago I used to “run in” new motors hanging in the wires down in a bucket of fresh water. I did the same whit new brushes, this kept the motor cool and the commutater clean. It worked for me! :lol:

 

[i_build_stuff]

I would just put the motor in a little plastic box (maybe a pill-bottle), and have the shaft pass thorugh a greased-up rubber grommet. You may want to have a little packet of silica gel in there as well, to absorb any dampness that might work its way in over time.

If heat is a problem, you could always wrap a few loose turns of heavy copper magnet wire around the motor, and extend the ends out into the water. Air will blow out the holes at one end of the motor, past the cooled wires, and back into the holes at the other end.