Converting a Lawn Tractor to Electric Power

[anorlunda]

The ebay ad you linked contains the words,

Features:

[TD]Hall Motor Control

[/TD]

I think that is what @Tom.G referred to.

Edit: It also includes the wiring diagram for the controller.

 

[surfsup]

Ok I think I found a controller that would work, what do you guys think of this one? I would get two, one for each of the 40V ryobi motors:
https://www.ebay.com/itm/DC-6-50V-3-Phases-Brushless-Motor-Controller-No-Hall-BLDC-PWM-PLC-Driver-Board/253794933276?hash=item3b175b5a1c:g:~rsAAOSwLXFctH63

16A peak 20A
6-50V operation (my battery is 48v)
built-in pot for speed
No hall (I thought I could just leave that disconnected)

 

[hutchphd]

I note this is also available at Banggood where there is some more info. I think this will do well and don't really know exactly what the (hall) speed sensor does so this probably better. These motors can probably go faster than you can safely go incidentally...

 

[DaveE]

Looking at the Home Depot ad, new Ryobi mowers claim 40V brushless motors. If the motors have three wires coming out (and probably not colored green or red or black) my guess is brushless. Which really means 3 phase square wave AC is provided by the controller to these wire at the appropriate frequency to make them spin synchronously. But it would certainly be far better to have some specs. What mower model did they come from??
You will need to know the amps to get a controller at very least.

Yes, I think 3 wires means BLDC motor. Here's some tests you could try:

1) Measure the resistance of all 3 combinations of terminals. If they aren't all the same then it's not a BLDC motor.

2) Connect the windings to an oscilloscope and spin the motors. If you see three identical sine waves (back emf) 120^o apart, then it's a BLDC motor.

 

[surfsup]

I note this is also available at Banggood where there is some more info.

Thx for the link. Cheaper there. I'll order a couple.

These motors can probably go faster than you can safely go incidentally...

I just want to set the speed to around 2800 rpm, and then forget it.

 

[surfsup]

I'll check the resistance.

Connect the windings to an oscilloscope and spin the motors.

Man, should I bust out the ol' oscilloscope? Now you're all thinking, "you have a 'scope and it's in the closet? WTH is wrong with you?" I used to build valve guitar amps.

 

[surfsup]

Update...So I have the drive motor, controller, throttle, battery etc all on the bench and it seems to be working well. I am waiting on the controllers for the two deck blade motors still. More on that later...

i have a question on the fuse (don't have one yet). Not being familiar with these brushless motors, it is a 2000w motor on a 48v battery so if I divide I get 42A so is there a spike under load? Anyone have an opinion on whether a 50A slo blo would be ok? Or do I need to get one that is closer to 40A?

 

[Tom.G]

The fuse size also depends on the characteristics of the controller; and if you expect the fuse to also protect the controller.

For instance if the controller has Soft Start, Current Limiting, and built-in protection to an overload, put a 100A fuse at the battery to handle both of them (and probably another controller and fuse for the traction motor).

If the controllers do NOT have Soft Start, Current Limit, etc., use a separate fuse for each power circuit (probably a 60A-75A Slo-Blo) to handle the motor start-up and when the blades hit something solid. The electronics in the controllers are effectively a very fast, expensive, fuse; as such, they protect the fuse by blowing first.

Cheers,
Tom
(Note: Be sure to have spare fuses on hand, and maybe a controller!)

 

[berkeman]

The electronics in the controllers are effectively a very fast, expensive, fuse; as such, they protect the fuse by blowing first.

 

[BigDon]

Hello sir.

May I ask why?

I was a professional greenhouseman for more than ten years and my gardening skills are such that the tax adjuster claimed my landscaping added a full 15% value to my parent's home.

Gas mowers always outperform electric mowers. They can't spin the blades fast enough to prevent tearing the grass blades, unless you maintain the blades scrupulously sharp. Then the frayed tips die back until even with the main body of the grass blade. Individually the effect isn't much, but collectively this can put a brown sheen on your lawn or simply keep it from looking as green as it can be.

 

[BigDon]

Oh, and a caveat I feel compelled to relate, as I've seen no less than three intelligent men hurt themselves in this exact manner.

On a normal gas mower sometimes one has to clear the "bell" or underside of the mower. Especially if the grass is wetter than you thought before you began mowing. So what a lot of people do is tip it on its side and clear it out by hand. It's safe, there's a deadman's switch on the handle, right? What you HAVE to do before working under there is disconnect the spark plug! It's a simple pull of a cable in most cases. If you don't...

Invariably the blade will get in the way of the wet grass removal and you'll move the blade to another position.

And run the risk of compression starting the engine! For even one brief cycle that is a bad thing.

Unless of course you're a wanted man, then you no longer have to worry about all those pesky fingerprint issues.

And microsurgeons today are wonderful people I might add. The last guy I knew that this happened to you couldn't even see the scars where they reattached his fingers. (Unlike the first guy back in the mid seventies.)

 

[Averagesupernova]

And microsurgeons today are wonderful people I might add. The last guy I knew that this happened to you couldn't even see the scars where they reattached his fingers.

Oh, well knowing this I'll be much less careful without worry. Lol. No, not really. They can do some amazing things now but I still value my digits being kept uninjured.