Sources for motor and control electronics

Yup, but most subs are around 6 foot, not 12 foot, hence my post here and not there.

Michael

They may still be the better source as most people here build robots in the 6-12 *inch* range. A few are up to 18-24 inches or so.

Try the companies that deal with wheelchair motors and electronics. Many of these motors are in the HP range you're looking for, and more, and they offer the control electronics for speed and reversal. Try National Power Chair for starters. Bring your wallet.

-- Gordon

So far I've asked a submarine forum, a model engineering forum, a boat building forum and this one. With varying success

Sure. Here's a comparison table of larger DC motor controllers for robotic applications.

Here's another comparison table.

These controllers are in the 1KW to 24KW range.

John Nagle Team Overbot

Hi,

I'm building a model submarine it will have a displacement of around 500kg and a length of 4m. Having worked out a rough idea as to the size of the motor required, 3hp. I'm now looking for suggestions. Sites like technobots don't stock ones large enough and so I'm struggling to find an answer. Then there is the matter of how to control the speed. Ideally I'd like proportional control.

So, does anyone know where I can find a large enough motor, ideally with the electronics to control it? The onboard power will be provided for by two 12V batteries, of which the AH is still undecided.

Thanks

Michael

I think elevators may use large DC motors (or at least use to). I suspect their types of controls would not be very efficient for use with batterys. The rec.crafts.metalworking grup has a large following who may have come across something like you need. Railroad groups might be a resource as trollies and such might also use DC motors.

So, not knowing much about submarines, what's wrong with the trolling motor that was suggested? It sounds like an ideal pairing of packaging and capability. Not to mention mass consumer pricing. I'm not at all sure how many pounds of thrust equates to 3 HP, but I think I can get pretty close by figuring 2.5 to 3 kW battery draw. The controller? I haven't built anything that large, but the only real difference is the power mosfets.

$$$$$$$

How much more power do you think you'll need for a 12' vs. 6' sub? Power required to drive at a certain speed doesn't increase proportionally to the length. I don't do subs myself, but I do build model surface ships. I can tell you that getting them sca;ed DOWN to a reasonable speed is a challenge, sometimes. The motors & speed controllers that electric boat racers use produce a lot of power. I'd expect that you'd have to gear down significantly, even if you used a mild model marine motor(s) & electronic speed controller.

JM

I see. WalMart is selling motors with good specs for $200. I didn't think it that bad for a housed motor complete with prop and controller. Do let us know if you manage to find a 3 hp PMDC for much less than that.

Thanks for all the comments

What about:

10 1/4Hp motors, all sharing same shaft. To control, step the voltage up/down. So have 8 6V batteries, them connect them in such a way, so that the draw on each battery is the same. Very cheap, and should work. And no complex controllers to interface. Only problem is that isn't that efficient.

Michael

I ve seen trolling motors on Ebay for as little as $30....

Obviously big bickies involved here - if you are going to use a 24v motor then you are looking at around 80+ amps, or at 12v around 160amps

I wonder if a 24v truck starter motor would do the trick - pick one up from a truck wreckers at a reasonable price I should think.

I think you might have to look at PWM for control - a PICAXE could do the signal stuff, but you would need some BIG transistor or such etc to handle the current.

David - who doesn;t know much about this stuff, but is offer> Hi,