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

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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rickharris16 days ago

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.


Most cordless drills are still brushed motors though.

True.

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

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.

iceng16 days ago

There are low RPM variable speed handrills...

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.

TypeNameHere (author) 16 days ago

...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.

TypeNameHere (author) 16 days ago

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.