Speed controllers

Is it possible to run 8 motors off one speed controller.

Depends on power of each motor.

Normaly I would say that a 4QD NCC70 24V easely can handle 8 speed 720s 2 in serie 4 parallel.

But if you try to control 2 Bosch 750s on the same 4QD , youll lose a lot of potential power delivered by these motors. If the speedo doesnt fry.

In theory, a group of motors looks like 1 big motor to the speedo. But if the back EMF and total power drawn exceeds the capacity of the speedo, youll be letting out the magic smoke.

Im using NPC-02246 motors

Hmmm, those motors are 1/3th the power of a Bosch 750, with a pricetag 1/3th of the Bosch 750.
You could join 3 of those on 1 speedo and get the same power as 1 Bosch 750 on the same speedo, but for 6.5kg, wheras the Bosch 750GPA weigths 3.8 kg.

so can i run 8

Ben ...For your first bot Id suggest building a straight forward 2 motor two wheel drive bot.

Much cheaper and easier to implement ...perhaps two of the popular NPC-T64 Motors.
http://www.robotmarketplace.com/products/NPC-T64.htmlhttp://www.robotmarketplace.com/products/NPC-T64.html and a Robot Solutions speed controller either this http://www.robotmarketplace.com/products/RS-RS80D.htmlhttp://www.robotmarketplace.com/products/RS-RS80D.html or its bigger brother http://www.robotmarketplace.com/products/RS-RS160D.htmlhttp://www.robotmarketplace.com/products/RS-RS160D.html.

Expensive hobby bot building.

My choice Woody

Indeed it is :)
All info is offered for acceptance or rejection.

So ...In answer to your question can I run 8 ...YES
Is it a good idea ...I dont think so.

(Message edited by woody on June 25, 2008)

I concur Woody.

Team RCC uses the Sidewinder as normal heavyweight speedo. This speedo does a great job regulating 24-36V- 80A per side.

But 4 of the NPC 02246 motors on 1 channel. These will be limited to 80 amps total.
Meaning each, if their resistance is equal, will see 20 amps each, at best. Thats not a big load on those motors.
(I would use the way lighter Speed 900s then, better amp/torque/weight)
Oh well, if you want to waste weight on extra motors, no problem for me, just means another victim.

Right and what robot is yours
i will buy 8 speed 900s then will that be ok
on 1 speedo or 2

What do you want to do with those 8 motors?

The list of robots Mario, Rick, and I have you can find on http://www.team-rcc.orghttp://www.team-rcc.org

create a fast and powerful robot of course

(Message edited by neontetra23 on June 25, 2008)

In that case Id get a couple of magmotors, 2 s28-400s, thats way more power than those NPC NPC-02246 motors could produce for way less weight. More motors just overcomplicate things, and Keep it Simple is still the best policy in Robot Combat.

Where are you from Ben? US, UK?

uk and im not made of money

The difference is 142 dollars, less even if you count shipping costs since 16kg for 8 motors will cost more to ship than 2 mags for 6,5kg.

not made of money??????

Ben i am sure it will cost you more money to buy 8 speed 900 motors, add gears, mountings, all the gear you need basically for a good drive train with 8 wheels. i assume you are doing a wheel on each motor. the advice given is good advice. try and be thankful with the advice given they are roboteers and know what they are talking about.

Im beginning to wish i never asked

There is no harm in asking. But you are being very dismissive over some good advice given to you with your best interest in mind. Particularly Woodys advice is one I wouldnt ignore off hand like that.

ok but i think npc 02446s will be fine

have you built a combat robot before Ben?

are you going to have a weapon or are you thinking about making a robot in the storm/tornado style? i know storm has a weapon but imo there power and speed is there weapon.

also be prepared to get damage which will take up alot of your time and money, its cost £1000s over the years but the main thing is time fixing the things.

im not trying to put you off though, we love having new robots coming on to the scene! :)

Ben, how many wheels do you want to use?
And what size of wheels?

The speed 900s, if bought at a normal RC shop- as they are normal, large RC motors are about £30 each.
Advantages. All stats are know, they are simple, rugged motors with build in radio interference suppression. And not that difficult to aquire, any decent RC shop can deliver them.
But their main disadvantage for heavyweights is the high RPM and low torque. @12V they run about 7000rpm and have 1.1Nm stall torque.
All this for 665 grams per motor.

8 5 inch wheels with skid steer hence need for 8 motors

What speed is wished for?
And, what voltage intended?

And imagine your robot being an 4 legged chair... What amount of legs (wheels) is touching the floor at any time.

(Message edited by maddox on June 26, 2008)

15 Mph

Ill take 24V.

That means you need a 2 stage gearing of 13.5-1

I can already tell you, a simple single stage but custom gearbox with aluminium gears suited for a feather, without a motor, is approx £40.
And thats not even commercial, but a price between roboteers.

Imagine a 4 times higher price for each. At least, for a heavyweight robot.

Hello!
What is the best speed-controller to use in a two wheeled robot driven by two S28-150 Magmotors?

The best, unaffordable.
Useable, about any current limited speedo we have seen used with succes in heavies.

I would use the Sidewinder.

I would not use a Sidewinder with Mags. Not even the 150s.

Id think about a Roboteq or similar.

RoboteQ ax2550..??

Will 120 A be enough for a 28-150?