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How to operate a brushless motor (without complex systems)? {Sea Scooter Project} Answered

I'm trying to make a mini "sea doo" sea scooter for under 100usd.  Im wondering if its possible to run a brushless motor with a simple switch rather than a complex arduino based system.   I will probably enclose the project in a 4-6in diameter pvc pipe with end caps and run the propeller shaft through a smaller pipe with 2 bearings on both end to keep water out.  I would prefer to have a hand drill style switch for variable speeds but if that's not possible single speed button will work also.  Also are li-po batteries a good option for this.  

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rickharrisBest Answer (author)2017-07-04

Peter doesn't discuss the detail of his design but covers some of the pitfalls he found.

To run a BLDCM the easiest way is to use an RC ESC. This takes the battery and a control signal to give a variable speed signal to the motor and includes all the driver tech.

You can easily provide the speed signal from a servo tester (a few $).

Your option of a cordless drill also has the required electronics built in which may suit you.


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steveastrouk (author)rickharris2017-07-05

Most cordless drills are still brushed motors though.

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steveastrouk (author)rickharris2017-07-06

We have a BLDC Dewalt in the shop here, its incredible !

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rickharris (author)steveastrouk2017-07-07

I took a look at my relatively cheap generic drill and impact driver bought recently and to my surprise they both claim to be BLDC motors.

i guess a lot of BLDCMs are being made now perhaps that's why they are so cheap on the RC hobby market.

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iceng (author)2017-07-04

There are low RPM variable speed handrills...

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steveastrouk (author)2017-07-04

No, you really need some smarts to run a BLDC motor, it doesn't have to be an Arduino, but you do need more electronics than a switch.

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TypeNameHere (author)2017-07-04

...hopefully last question. In the original post I was hoping for a drill style pressure switch... Do you guys think i could just use an old thrift store drill with the propeller in the chuck lol. Seems a little too easy but hey if it works. Drills usually only go to about 1500 rpm but perhaps i could modify the gear box and take out a few gears sacrificing torque for rpm. From there i could power the drill using either the normal battery or a rc car battery.

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TypeNameHere (author)2017-07-04

Also how much thrust would be created in water by a say 5in diameter 3 blade propeller spining at about 3000-6000rpm. I looked online for a formula or something but was unable to find anything.

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