9504Views9Replies

Author Options:

Running DC motor underwater? Answered

I have heard that DC motors can run underwater and am trying to build a project with them running underwater. I recently tried running a brush less DC cooling fan underwater and it broke. Meanwhile I tried another mini DC motor, the kind that cost $.99 each and it worked fine. Does anyone have any ideas why one worked and the other did not? Does it have to do with being brushed or not? Lastly would something like http://www.pololu.com/catalog/product/1117 theoretically run underwater? Thanks.

9 Replies

user
steveastroukBest Answer (author)2012-06-28

Brushed will work for a bit, brushless should work for ever, bearings permitted.

Select as Best AnswerUndo Best Answer

user
Hammock Boy (author)steveastrouk2012-06-28

Is a "bit" once or twice in the water or should I get most of their life out of them?

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)Hammock Boy2012-06-28

Once or twice in my experience. Brushless is the way to go.

Select as Best AnswerUndo Best Answer

user
Hammock Boy (author)steveastrouk2012-06-28

Any guesses as to why the fan broke?

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)Hammock Boy2012-06-28

WAY too much torque load ! You'd've run the thing wildly over current.

Select as Best AnswerUndo Best Answer

user
Hammock Boy (author)steveastrouk2012-06-28

would submerging it into a glass of water do that? it was only meant to move air.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)Hammock Boy2012-06-28

Yes, it would, and, precisely, water is 1000x more viscous.

Select as Best AnswerUndo Best Answer

user
TonyK33 (author)2016-05-17

Old but. The reason those oil pc's fans don't have issues is exactly that. The oil is non-conductive and the brushes don't arc and gap instantly.

Select as Best AnswerUndo Best Answer

user
frollard (author)2012-06-28

Somewhat related, I've seen under-oil PCs running with their stock 'air' fans 'blowing' oil over the heatsink in an aquarium filled with mineral oil. The fan shouldn't fail for torque - it runs much much slower but still works...surely to the detriment of the coils if it runs near stall current all the time.

As steve says; brushless never has electricity jumping any gaps, so the only point of failure was if the water wasn't totally pure it may have shorted out the control circuitry driving the brushless-ness.

Select as Best AnswerUndo Best Answer