New buggy build but need help with braking controller

[Cyscrofer]

Hi all.
I've spent several months now making a new 2wd 4wd buggy...

24v 1000watt x4 13inch hub motors however the company who supplied the controllers haven't got a clue.
Lunyee Motors in China


The motors are all identical 8 wire hall brushless type.
3 wires for phased power 5 wires for hall control.

I asked for regenerative controller but with the EV ABS function which generate braking force electronically.

Instead I got 1000watt regen controllers

Although I have 4x disc brakes I only want to use for parking up not on the run.

I've seen at yet more great expense on EBAY there are EV controllers for brushless motors has anyone used or using them as an alternative way to braking brushless motors?

If not can anyone suggest any supplier or person who can help in this field please?

I've already spent a small fortune on this build and the last thing I wanted it to have to spend another £800 just to get brakes working.

I'd put up pictures but don't have anywhere to host them
Sorry.

[Burgerman]

Regeneration happens in ALL controllers. That IS the braking. The parameters such as how hard it decelerates, or how much added "braking" you get are all dependent on complex programming in the controller. That will not be present in the cheap chinese controllers. They are bog basic like a rc speed controller. If you buy non geared hub motors they will lack torque and lack effective braking and or eat huge currents to produce limited torque. It may still be adequate depending on usage which you didnt mention..

If you want proper programability you wont find it in cheap chinese controllers. The disk brake is usually only intended as a park brake on electric motors.

For example we here have a few membres using the roboteq controllers. To properly control those required a little extra programming in the form of a script like this ON TOP of the in built :

http://www.wheelchairdriver.com/BM3-con ... Script.txt

It allows amogst other things user controlled braking and acceleration and deceleration rates. Variable parameters.

[Cyscrofer]

OK great thats a total waste of 3 months and a grand of money down the pan.


Do you know of any decent dc motors hub units I can use
Spec...must do at least 25mph
Off road and on road
And stop....

[Burgerman]

No. For powerchair use and low speed control they are rubbish.

[Cyscrofer]

OK thank you.
Back to the drawing board.

[Burgerman]

Those motors you are using and controllers are intended for use on bicicles etc. Where YOU fit seperate brakes. Or use the existing ones to slow.

They are not much good for anything else. Sorry.

To do as you want you need to use geared motors or geared hub motors to get adequate braking and torque at low speeds for good control. And higher voltages used to get the speed you demand. So maybe 60V or 72V. Used with a script similar to what I posted above in that link in conjunction with say a brushless roboteq controller or rather 4 of them. Or two dual channel ones.

That isnt going to be exactly cheap.

Heres a 2 chanel or single channel controller that will allow good control and a fair bit of controlability. It will need the script or something silmilar if you want it to work with any kind of refinement regardless on top. https://www.roboteq.com/products/produc ... hbl-family

2 of these would drive 4 geared hub motors.

[Cyscrofer]

Cheers fir the information.

Looks like 3months of work in the bin.

Just for reference these motors come with the tyres on.

13inch rolling diameter and disc brakes so thought with 1000watts of power per motor I would t of had any issue with lack of power.

I total I'm throwing 4kw of power down and that should be easily enough to get a simple buggy and a body up and over any reasonable hill even at 24v.

With 24v and 270aH on tap enough that to happily start a fire....lol

OK I won't gave the low down torque that the dc brushed sets give but then I will have 20mph plus hopefully easily.

However I still don't like the mechanical brakes and want auto braking like you get on the brushed units.

So the future is either sell this as is and start again or see what higher reving brushed motors I can get using 24 36 or 48v battery sets and totally rethink the entire project.

Cheers for the help.

Love your designed powerchair.

Can I ask where you got the motors and wicked wheels from?

[Burgerman]

The motors are just powerchair motors running on 45V.

Why?

Because without the volts, the only way to get the doubled up speed, is to have a mechanical advantage. Gearng. And that results in inadequate torque. It doesent matter if we are talking about hub motors, or brushed DC geared or whatever. So you could get the speed with bigger wheels, or taller gearing. Or direct drive and no gears in your case. In every case however the result is identical, double the speed = half the torque and a very high current draw under load. So absolutely the worst way to do it.

As they say in the EV forums, volt up, gear down.

Also the 1000w motor thing tells us exacty nothing useful on your motors.

A 300 watt wheelchair motor on 24V and LIMITED to say 120A by the controller takes 24V x 120A = 2280 watts. So does a 500 watt wheelchair motor. Or a 750 watt one... On 24V with a 120A limit they are ALL 2280 watts peak. And very little watts unloaded or at constant speed.

So saying you are throwing "4kw" of power down also tells us exactly nothing about torque. Also thats not much.
My BM3 chair has 2x 45V motors, at 150A per channel via roboteq controller. Total watts then is 45V x 150A x 2 motors = 13,500 Watts peak. On its "350 watt" motors!

Watts alone, esp when no voltages, or controller current limits or motor impedances are known tells us literally nothing about performance other than the point where they are at good efficiency, and the rating that they can do continuously without heat damage. The actual motor power depends on load, and voltage and the current limit you have due to the controller software.

It works like this.
Volts = RPM.
Amps = torque.
And in both cases the MAX free running unloaded speed and the current limit of the controller determines max torque.

So no you may or may not have enough torque - depending on your actual buggy design.

[slomobile]

This doesn't need to be a waste. What exactly is the problem you are having?
Will the motors move you? They should. If they have the power to get you going, they have the power to slow you down. Just not necessarily the ability to bring you to a complete stop unless you use the mechanical brakes for that last bit.

Why don't you want to use the disc brakes while running? Electrical and mechanical braking should be done at the same time and blended with mostly electronic at first followed by mostly mechanical. In practice, you just apply the mechanical brakes as much as you are comfortable with and the electronic portion reduces as your speed reduces. Its the same thing. Mechanically linking the 4 disc brakes is not expensive.

I can help you add on the small bit of programming if you are actually missing it. You may only need a proper switched brake lever. Worst case, you need something programmable like an Arduino to filter your drive commands. If you want these direct drive motors to function as brakes, all you need to do is command them to reverse while you are rolling forward, then reduce the amount of reverse applied as you slow down. When you are going fast forward, you can apply a lot of fast reverse and get a lot of braking torque and a lot of regen current. Careful you don't overheat doing this. But as you slow down, you have to apply less and less reverse current so you don't overshoot and start actually rocketing in reverse. This means as you slow, the throttle approaches 0. No more electrical authority to slow you down with motors, time to use a bit of brake to ease you into being stopped.

Wheelchairs get away without using proportional mechanical braking because the gearboxes multiply the friction force created by a stopped electric motor. Its doing the same thing, just in a less controllable way.

You said "3 wires for phased power 5 wires for hall control" hall only needs 3 wires.
What kind of control arrangement do you have? Joystick? Throttle and brake? What physical ability do you have to control the brakes? If none, we can have a large servo motor do that for you. Any wiring diagrams or documentation you have will help us help you.

[Burgerman]

I dont even know where to begin on that lot!

[ex-Gooserider]

You said "3 wires for phased power 5 wires for hall control" hall only needs 3 wires.
What kind of control arrangement do you have? Joystick? Throttle and brake? What physical ability do you have to control the brakes? If none, we can have a large servo motor do that for you. Any wiring diagrams or documentation you have will help us help you.

Typical Hall sensors I've seen need 5 wires, as you have 3 for the actual sensors, plus two for power and ground...

On the hoverboards I've taken apart, and other similar brushless motors the usual setup is a 5-pin JST type plug for the Hall sensors (usually using AWG 24-28 wire) and 3 separate heavy gauge wires (often with 'bullet' connectors) for the motor power....

ex-Gooserider

[slomobile]

Yup, good catch. Forgot about VCC and GND. The hubmotors I've been using have the 5v(others may use 3.3v) and gnd bundled with the temperature sensor wire and parallel it inside the motor. My 3 hall wires are each color coded to match 3 phase wire colors, but smaller gauge.

Hub motors can work, they just work differently.

[Burgerman]

Hub motors without gearing ALWAYS draw too much current and or lack torque at low speeds.

[slomobile]

Hub motors used to always be short on startup torque because the early brushless controllers were not optimized. He has 4 motors and the opportunity for much better controllers http://www.simplefoc.com/. Hub motors have improved a lot.
https://endless-sphere.com/
https://ebikes.ca/
https://www.youtube.com/watch?v=c96n0Ma2rLY&t=467s
https://www.youtube.com/watch?v=Ub4EP2_mAds
https://outriderusa.com/
https://outriderusa.com/pages/coyote-4wd-atv They are about to release a 4 hub motor version of the Coyote with the same battery module and similar performance.

[Burgerman]

Its not about the controller. Its about the motor physics. You would need enormous amps to make a brushless hub motor match a brushless or brushed geared motors level of torque or control.

The reason that the invacare brushless storm 4 chair (that I returned as impractical and unworkable for a refund) has been junked in favour of returning to the typical brushed motor is this.

With an EMPTY chair, using my clamp meter to measure amps on a battery cable, this chair took 192A to begin a zero speed turn in place. It managed that 2 or 3 times before shutting down to cool the controller. When I put my 20 stone in it, it did not manage to turn at all before rolling back power to save the controller after hitting 205A at the battery. Thats around 10 times more current than a brushed motor that is geared for the same speed. Invacare finally agreed with me and then it vanished off sale. You cant beat physics.

[slomobile]

How does that help him? We know that brushless isn't a choice you would make again. It doesn't matter. He already has what he has. We can help him make the best of his situation rather than make him feel worese unnecessarily. He did not make a terrible choice, just not your choice. Maybe the results he gets are not optimum, they can be good enough. A 4 wheel drive chair can carry extra cells for range when he needs it and leave them off when he doesn't. It gives him lots of redundancy in case something breaks. OP seems to have gone MIA now anyway. We don't really know what the problem is, other than he didn't quite understand what he was ordering. We don't even know the specific equipment.

[Burgerman]

He did not make a terrible choice, just not your choice.

Yes he did. Not terrible, just pretty much unworkable. Its also not about "my" choice. Or his. Only what is workable and what isnt. He ended up here trying to fix the unfixable due to incorrect choices of parts and ack of understanding over what he was doing. Many of us here have been through all of this over the last decade or longer. Will for e.g researched all this and came to the same expensive conclusion. He ended up having to have motors purpose built at very high cost and use gear reduction. I figured this out in a similar way. Many on here have.

The physics does not just ignore things because its unfortunate or inconvinient that he chose the parts incorrectly because it doesent want to upset anyone. It just is what it is. Theres no my choice or his choice. Only what works and what doesent. What he has will be extremely efficient and fast once rolling. Buy at 0mph to very low speeds it will need huge currents that he cannot provide with those batts or controllers. And he wants controllers that are much more configurable than the basic speed controllers - much like a powerchair controller in order to make it brake and decelerate and to drive well. Been there and got the T shirt. Things are not as obvious as it all first appears.

How does that help him?

It shows him where the issues are. And so gives him a chance to either stop throwing good money after bad or to allow him to deal with it in some way. Although I cant think of one at a sensible cost.

[ex-Gooserider]

The other factor you might not be fully accounting for in your dislike of brushless motors is the intended application... I agree with you that they are questionable for a power chair (Though Shirley seems to do OK w/ his...) but only because you are doing a lot of slow speed / tight quarters activity w/ them...

OTOH, the OP was talking about a 4WD off-road buggy, which presumably would be doing a lot less in the way of slow speed or tight quarters so the high power draw in a zero-speed turn isn't likely to be as much of a problem, and the lighter weight and higher energy efficiency of a brushless / gearless motor is an advantage...

IMHO the problem is dealing with the starting torque requirement but if you keep that activity to a minimum, it isn't as huge of a deal...

I actually had a kid show up at the Asylum today that is working on a project to adapt an electric trike (originally designed as a power assist pedal bike) for use by a quad... (I have pointed him at WCD, so he may be showing up asking for advice, please be nice to him... ) I pointed out that starting torque may be one of the bigger issues he has to deal with... Other than that it seemed doable.

ex-Gooserider

[Cyscrofer]

The project is now going to dc motors.
Proven rhino controllers and the rest is just down to pure grunt.

Can you run the Rhino controllers on 36 or even 48v or is that a big nono.

[Burgerman]

Dont do scooters so not sure. Most are 24V limited like powerchairs but some bigger ones do 36V.

But increasing VOLTAGE does not change torque by even 1% as thats is determined only by gearing and max Amps. Unless the motors do not reach stall torque and the controllers current limit due to heing high impedance. But even a weedy powerchair motor draws 150 to 300A at 24V stalled. All above the controllers limit.

If you want more torque you need to gear down, volt up as the EV forums say.

Thats why I used 8mph motors, and ran them at 16mph at double the voltage on my BM3 chair. That allowed the same torque as an 8mph motor, at the same 120A limit, plus a 30A gain from the roboteq 150A per channel controller. And the volts allowed the speed to double with no loss of torque.

That wont work on a scooter controller. Unless you use shorter gearing and a 36V industrial controller.

Amps = torque.
Volts = RPM and so speed.
Torque x rpm = power. Or Volts x Amps = watts. Same thing.