Speed controllers to use with mobility scooter motors?

[SnowLabs]

Hi everyone, beginner here! (First post haha)
I'm looking to put together a testbed bot to build off to get started, and I was going to use some mobility scooter motors for the drive. For the ESCs, I was going to use the 85a Tz85a's because I know they're popular, but they are brushless. A lot of people use mobility scooter motors - but aren't they likely to be brushed? If so, can people recommend any high powered brushed ESCs to use? Should I go for the Botbitz 85a Brushed Tz85a, or even the Botbitz 30a Brushed ESC? Would the 30a one be powerful enough for most scooter motors? - Sorry I can't give specifics, most scooter motors on eBay don't detail the specs. Cheers all!

[R9000]

Welcome to the forums, yo! Now I'm not the most qualified to talk on motors yet, as I have very limited experience, but I'm willing to bet you'll need at least a Tz85a for scooter motors. 30a ESCs won't cut it, and you may even need something more powerful than an 85, depending on what you use. If you want, you can buy the Tz85 brushless version off HobbyKing, and mod it to be brushed using this guide. Anyway, hope you have fun building, and I'm sure plenty more people will have important advice for you too.

[maddox10]

For very low power scooter motors the 30A "could" do the job. But then we're talking 10kg units with 250W of motorpower.
Those will move a heavy at a snails pace.

Botbitz TZ85 can do bigger motors, but I wouldn't go over 24V 600W. What is barely useable for a brick that moves at leisurly pedestrian speed.

To give you an idea. Most heavies use 36V 80A or more. And that is with esc's that have peak ratings of 120A+.

[Rapidrory]

Yeah, speed controllers get expensive once you get above 500W motors (about the limit of a TZ85). Wheelchair and scooter motors can be used, but as a rough idea, most heavies use motors with about 1200W peak power (Bosch 750s).

If it's just a test-bed bot though, wheelchair motors and Botbitz TZ85s will be fine. These motors would probably also work ok http://www.ebay.co.uk/itm/ZY1020-Ele...kAAOSwz2lXDMyJ

A better but more expensive ESC are these: http://www.robotpower.com/products/vyper_info.html

Quite a few heavies use these and they let you run motors up to around 1500W

[SnowLabs]

Thanks for the helpful responses guys!

So I've ended up getting two Robotpower Vypers and I've decided to get a couple of motors and do the drive from scratch. I'm on the hunt for the two drive motors... any suggestions? I'd get a couple of Bosch GPAs but they are really hard to find. I'd need something in that power range at 36v. To be honest, this is all for a HW I'm building with the intention of applying for Robot Wars series two. I'm one of those guys that watched Robot Wars fanatically on TV when it was on, now I'm 22 and I'm building one with my dad, who I'm pretty sure is more enthusiastic about this than I am!

I'll post a build diary when I've got more to show, I'm pretty sure what I'm building is somewhat unique..

[Rapidrory]

Unfortunately most of the good motors are sold in the US, and the shipping/ import costs are often more than the motor. If you can get hold of them though, 3 inch Ampflows are used a lot, and can even be bought with gearbox and wheels attached. Another easy to use unit are the NPCT64s. For UK options, you can get 1000W/ 800W scooter motors off ebay pretty cheaply; they'll shift your bot fine, but if it's meant as a ram bot or similar then they'll probably be a bit lacking. Other motors available are Iskras from Italy(?) which are similar to Bosch 750s.

if your budget allows, then things like LEM 130s and Eteks are also available, but they're potentially over kill :L

[SnowLabs]

Thanks, I'll have to do some more research for motors.
As for the gearing and wheels, I'm going to build something from scratch - the bot I'm building will require two large wheels for drive.

I'm currently looking for wheels with a diameter of 12" or so. A lot of the wheels I'm looking at have been wheels for industrial trolleys, and have ball bearings making them impractical for drive. Do people normally get something like go kart wheels with wheel hubs, or something else?

What the best way to mount the sprocket and wheel to the axle? Do people normally get something custom made, ie gears and axle that they get keyed? Sorry for all the questions, I'm just trying to work out the best way to mount the wheels/sprockets.

[joey_picus]

The go-to solution back in the day was indeed go-kart wheels, which came with a load of standard drive components that mounted easily to each other - as long as you were happy using chains and avoiding punctures...You can always knock the central bearings out of commercially available wheels and make your own hubs, and in this day and age you'll probably require some degree of custom components no matter what you go for.

It's also worth noting 12" is pretty big if you're going for a low to the ground approach - standard go-kart front tyres are 10", and a lot of modern heavyweights are under 200mm for height...

[SnowLabs]

Thanks for your help. The design I'm going for is invertible, that's why I'm looking at wheels that big.

[typhoon_driver]

The T64s from the US are excellent bolt in solutions. Yes they cost a bit more than just a standard motor on it's own but the fact that they have the gearing sorted in a single unit and if you get the adapter plate at the same time, the majority of sack truck wheels will bolt straight on. Once you factor in the cost of gearing etc there's not much in it.

[Rapidrory]

The other advantage of NPCT64s is that you can bolt big wheels directly to them; my bot uses them with 500mm wheels (still small compared to Gabriel; there's no such thing as wheels that are too large :P)

The gearboxes are a little fragile for full combat as shown by some of the US bots, but as long as the wheels don't take a direct hit it should be fine.

I'm looking at moving to 1000W scooter motors with 2 stage chain reduction, mainly for the sake of availability and robustness (T64s probably shouldn't have 500mm wheels bolted to them :L). The usual ball park figure is to aim for 12-13mph, so I'm looking at using a ~12:1 gear ratio.

[maddox10]

The Chinese My1020 motors come in a few flavors, and ain't that bad in construction.
But I would recommend chains for reduction gearing.
The shaft ain't the the thickest I've seen for that amount of power. Now, some come with a small sprocket, and for a low gearratio first stage it should do.

The Italian Movimotors are also interesting, as Brutus demonstrated, but need more work to be ready for RW.

Iskra , a Slovakian brand, is very good in construction albeit a tad heavy. Those have so many variants it's even difficult to find the one you need/want.

[typhoon_driver]

The 800w 24v iskras are only around 2.5kg if my memory serves me correctly. Completely sealed as well so chance of crap fouling the insides or getting stuck to the magnets.

[SnowLabs]

Ok, so I've have the Vypers on order for quite a while now... and they're still awaiting stock. It seems like there's a problem with the manufacturer. Does anyone have any suggestions for an alternative ESC? Something in the realm of 36v 120a.

[maddox10]

Wotties spring to mind.
Mytras is also an option, if you can contact the maker of those.

Roboteq is a direct commercial option.