# Motor Selection Confusion with Mower Conversion



## SolarCzar (Apr 25, 2013)

Hey guys,

Running into several math problems, with the biggest being financially oriented.

I have a 20 year old Toro Zero Turn mower whose HydroStatic unit finally went out ($700 to replace) and the 24hp ICE has been giving me minor issues as well, so what better time to look into my first Electric Conversion. Also note the hydrostatic drives on this mower have been the biggest service problem since day 1, so I'm not excited about replacing the unit if possible. If I replace the hydrostatic unit, then I'll just probably sell the mower and go to another ICE.

I've been reading the threads contemplating my engineering and was originally going to convert the ICE with a dual shaft PMDC to drive the blade deck and the hydrostats. Now that the hydrostat went out, I'm back to trying to figure out a more cost effective means to motorize. Current design right now I'm looking at Montenergy ME0909 4hp PMDC for the 2 drives ($365 x 2 = $730) (feels like overkill), dual motor controller ($200-$400 depending on brand), and I'm looking for some single axis joysticks to replace the handles ($??). Then use a Montenergy ME1004 10.5hp PMDC with no controller ($525) just a switch relay ($10-$15)for the blade deck. Problem is that I'm over $1600 and I haven't bought batteries. Haven't found any used motor providers around here that fit my voltage or size needs.

Some of the threads have suggested using 12-24v winch motors for some applications. Can I use a 24v motor for the hydrostatic drive replacement? 1-2hp should be fine, but not sure about 1hr continuous duty on this type of motor. Also not sure about the wiring of all the solenoids and using a single axis joystick as the forward/reverse switch for each motor. Lot of solenoids.

I'm reading and reading, but sure would appreciate some experienced direction from real experts...


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## dcb (Dec 5, 2009)

so, you want to get rid of the hydrostatic unit and have independant/reversable motors chained to the drive wheels so you can do the 0 radius turn thing?

You don't need reversable for the deck, just a right sized inexpensive series will do there.

Series are the easiest to find, but shunt (or even sepex) are easier to reverse (unless you don't mind clacking 2 large dpdt relays every reversal, or sorting out large igbts/mosfets and drivers). 

And you could use a single 2 axis joystick and a $10 microcontroller board to translate that into forward/turn for the controllers. I.e. move it forward and right and it goes forward and to the right, move it straight to the left and it zero turns left, and pull it backwards to go backwards straight/left/right.

You might see if anyone has done a tank controller, or skid steer.

Edit, for the bare bones cost, a microcontroller (and programming), and some gate drivers, and 4 half bridge IGBTS (like these $10 100 amp units, much larger sizes available) is really all you need hardware wise to control series motors, plus a regular joystick. But it gets into the electrical engineering a bit (plus software development)
http://www.ebay.com/itm/Toshiba-MG1...863?pt=LH_DefaultDomain_0&hash=item3ccb2d5e47

for "cheap" series, You need 4 "fancy" gate drivers (i.e. dc-dc converters and optos) so you can pwm the high side, and you can switch the low sides "slowly" with a basic low side driver (with proper software safeguards). If you get extra fancy you can use 2 opto gate drivers on the high side (one each motor) and another "direction selector" opto(per motor) for directing the gate signal to the right igbt, cutting another ~$30 out of the hardware costs. Dont forget the bus and capacitors. Maybe $160 all day for a complete 100 amp tank controller with a lot of scrounging and learning, all diy, and dual series motors.


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## dcb (Dec 5, 2009)

edit, scratch the series motor unless you don't mind dissecting them and setting it up to reverse the field or armature (only the rotor or armature is in the h-bridge). I'm definitely not a motor expert  There's still a lot of $ to be saved w/series, but you would have to live with neutral brush timing also.



frodus said:


> On series wound controllers, they don't go in reverse, just 0-100% in forward, so that is one issue.
> 
> Also, series wound motors don't care about the polarity of the power coming into the motor. If you switch the polarity of the motor cables, you still rotate the same direction. To get reverse on a series wound motor, you have to reverse the armature and field windings from eachother.


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## SolarCzar (Apr 25, 2013)

So yeah, you got the intent correct dcb, but you may be talking above me just a bit. Not much experience with gate drivers, so I'll have to go do more studying. I will check on the forum for anyone with tank/skid steer experience for direction, and I think I even remember seeing something on robotmarketplace.com that might help.

Problem is, I'm still not sure I'm finding motors you're referencing (especially when I need 2 of them). Everything is still in that $350+ range per. I may not have a choice for the mower deck, as the Hp demand will be so high to drive the blades, but if you come across examples of what you're talking to, I would sure appreciate a link and I'll go educate myself. Call me cheap, but I didn't want to spend $1200 on motors for this project, which is why I was trying to make the winch motors work. Your right, I didn't want the loud clacking of the solenoids, but willing to sacrifice if cost was in the way.


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## SolarCzar (Apr 25, 2013)

See the attachment diagram of what I was anticipating for the Left/Right drive on the mower....

The deck is simply a series wound motor (suggestions are appreciated but think I need 10-12hp) with the appropriate relay & safety toggle switch to turn on/off.


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## Ivansgarage (Sep 3, 2011)

I would look at robotwars or battlebots remember the tv shows? that is what i would look into, RC radio control, less hp if you don't have to haul your butt around.

You would have more room for batteries, it would be better to sit on the porch drinking a beer or Mikes Hard Lemonade, moving a joy stick then sitting on a stinking mower.

Just a thought..

Ivan


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## dcb (Dec 5, 2009)

searching ebay for winch motor is interesting (and they are reversable):
http://www.ebay.com/itm/NEW-RAMSEY-.../120823268704?pt=BI_Pumps&hash=item1c21a0c560 $89 a piece, don't know specifics or suitability.

plus they have reversing solenoids:
http://www.ebay.com/itm/Winch-Motor...oid-/290374830394?hash=item439bb0493a&vxp=mtr

A couple center off/momentary toggle switches would get you rolling and zero turning at a fixed rate.

plus solenoids, http://www.ebay.com/itm/NEW-SOLENOI...H-D-/131057470818?hash=item1e83a24d62&vxp=mtr


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## dcb (Dec 5, 2009)

here is a hookup for one motor with a three position switch









googled for MBJ4407
Seems like a reasonably affordable experiment anyway.


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## SolarCzar (Apr 25, 2013)

Funny you should mention that Ivan...I happen to have a Futaba transmitter and receiver for another project and if this works, then at least for YouTube I thought I would have to make a contribution. 

I'm going to do some more reading and hopefully some of the other guys on the forum can weigh in on the winch motor viability. I'm pretty sure it will work, but concerned about the 1hr continuous duty and heat. If room, then I could add a fan. The hydrostatic units have fan blades to help cool, so might be able to reuse them.

If no one weighs in with information that makes this a really bad idea, then I think I will order to give it a try.


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## major (Apr 4, 2008)

Most of your power is needed on the deck: 










This is a 3 blade 60" monster with a DC Compound 7" dia motor running at about 32V. The tractor needs less than 1 hp to motivate. Maybe more if you have hills.

Forget about winch motors unless your duty cycle is less than 3 or 4 minutes. That would be a small yard. Look at what others have done. Search for mowers on EVAlbum. And here; there are a few. U-tube has some also.

You don't have to send a lot for the electric parts, but then it will take some research and elbow grease. And maybe your existing donor won't be the best suited for the electric system you can put to it. 

BTW, I've seen several new commercial electric riders available this year. Haven't seen the prices yet. 

Good luck,

major


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## dcb (Dec 5, 2009)

listen to major on the winch motors

http://www.diyelectriccar.com/forums/showthread.php?p=377784

But what would be an economical source of drive motors for something like this?


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## SolarCzar (Apr 25, 2013)

Ok, after some down time over Easter, I realize that I still need variable speed control of the motors to control some slower movement around objects and turns. Guys, I really want to do this and get in on the revolution, but there has got to be a way to do this that will not to break the bank. I found this motor and I've reached out to this Chinese company to get some more specs...
http://www.ebay.com/itm/171295043045?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

I really don't like ordering from China for parts like this, but I'm really struggling to find a decent motor for under $400, and I have to buy 2, speed controller, joysticks, etc...plus I have to find a 10-15hp motor for the blades. I expect that one to be expensive, and I haven't even gotten to batteries.

I'll keep looking, but looks like it will be cheaper to spend $745 on a new hydrostatic pump, because electric conversion doesn't seem to make financial sense, just environmental.


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## dcb (Dec 5, 2009)

dunno how durable those are, and it occurs to me that you may need a jackshaft if you have a high rpm motor. Larger and slower (or smaller but geared)

FYI, maybe something like 2x MOT-K24400

(halfway down the page)
http://www.electricscooterparts.com/motors24volt.html#koll

It won't be fast, but 400 watts x2 geared down might work.

It is a brushless with built in controller (don't go over 28v). And they are fairly easy to reverse, you switch a couple wires (or pull the wires out and attach them to switches). $119 apiece. They have another reversing option, which is to dig into the potting compound to the controller chip and attach a lead to the reversing pin (I've done it on a 2 speed retro-direct scooter).

Also they can be used with a hall effect throttle and a 5v regulator. Or do a custom arduino thing to translate the steering arm positions into appropriate voltages/reversing signals.


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## SolarCzar (Apr 25, 2013)

Very interesting DCB, let me reach into them and get some specs. I don't know if 1/2 hp x 2 would be enough for propulsion, but seems like it would provided the motors could handle the torque. Total weight with me on the mower would be about 800lbs. I have 1 hill that's about a 15-20 degree incline undulation, but the rest of the yard is flat as a pancake.

Definitely, the price is right


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## Woodsmith (Jun 5, 2008)

Could you get hold of an old electric wheelchair or mobility scooter? If you find one with a geared motor to each drive wheel then that is a matched pair of drive motors and transmissions sorted. A wheelchair would also come with a controller and a joystick control for zero radius turning.

Then you just need a small forklift truck motor for the mower deck. Perhaps a 24v truck with the drive on a single steered wheel would be suitable.


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## dcb (Dec 5, 2009)

well the wheelchair is an excellent idea, it caused me to look up what kind of power is used on wheelchairs.

looks like 180 watts X 2 for 300lb load.

http://www.ebay.com/itm/INVACARE-NU...972?pt=LH_DefaultDomain_0&hash=item258b380ba4

at 800+lbs/800 watts you are still looking at wheelchair like performance. But the price is right


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## thealbertaguy (Apr 21, 2014)

major said:


> Most of your power is needed on the deck:
> 
> 
> 
> ...


Hello Major, 
Is that your tractor? I am looking at getting 2 like that and a red one (can run a tiller as well) and bring them back from the dead. What do you recommend?
Cheers,
Thealbertaguy


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## Frank (Dec 6, 2008)

That looks like an Electrak (E15?) but with a different mower motor than mine. Ours gets used to move a lot of snow too.


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## major (Apr 4, 2008)

It's an E15 I think. Belongs to a friend, Tony. I have a couple of 12's in bad shape/not running. I have been meaning to restore them for years. I'd recommend PWM controller and Lithium battery with new charger. It takes a lot of work to keep the old control system operational.

The original deck motors were also troublesome which is why Tony and I went to the big monster deck. Tony has used his for over 20 years. He got tired of replacing batteries so installed an Onan welding generator and runs on gas. Puts out about 32VDC. He can also weld with it. Calls it Weld 'n Mow


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## Frank (Dec 6, 2008)

I use ours as much for snow removal as grass cutting (with a blade on it obviously, lol.). The PbA batteries are an advantage in the winter. The best thing? It is quiet!


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