# EV Tractor (and other outdoor power equipment) project in NY



## major (Apr 4, 2008)

muns53 said:


> .......With the 38" deck on the tractor, it takes me about 90-110 minutes to mow the yard,.......... I am considering the Mars ME1004 motor as a primary suspect. It's a brushed motor and doesn't require a controller. The shaft size/diameter and the performance specs appears to match the stock 13HP Briggs&Stratton gas motor pretty well.....


Hi Muns,

How does a wimpy PM motor rated at 6 to 9 HP match up to a 13 HP B&S? You're gonna need a bigger motor 

Mowing is a bitch for electric motors. The propulsion requirement is usually low, under 1 HP barring hills and flat tires. But the blades are big fan loads with a sh!tload of debris thrown in running continually. How often does that B&S bog down over a patch of tall or wet grass? 

And that continual load is also a bitch on the batteries. Say you get 4 nice deep cycle Pb-Acid 200Ah rated batteries. You'll be lucky to get 100Ah at load without excessively draining them. So for a 2 hour mow job that would be 50 amps average. 48V times 50A = 2400 watts which would translate to about 2.5 HP shaft output for the motor. Would your mower operate with a 2.5 HP gas engine?

I called the brushed PM wimpy because it is not tolerant of overloads nearly as well as a robust would field motor. And when you run one without a controller you can easily severely overload it because of no current limit. A clogged deck would spike the motor current and it is likely the motor would smoke before the fuse could blow.

But hey, I don't want to discourage you. I love electric yard tractors. I have several, but don't mow with any of them. And I think that small EVs like this are an excellent means for the beginner DIYer to gain experience with EV conversions w/r/t batteries, motors, controllers, gearing, etc. But be careful not to sink your entire lawn care budget into this conversion expecting it to mow your acre next season 

Regards,

major


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## muns53 (Jan 13, 2011)

Major,

I appreciate the feedback, it's not discouraging. 

If you would, knowing my end-goal, please suggest a better motor/controller/pack approach.

Thanks!


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## major (Apr 4, 2008)

muns53 said:


> If you would, knowing my end-goal, please suggest a better motor/controller/pack approach.


Sorry, I stop short of specific recommendations. But a 6.6 or 7.2 in dia wound field motor would be far more robust and have a fightin chance. Batteries....maybe start with Pb because Li is expensive, but don't be surprised if you can't complete the yard on a single charge. Google around and find some examples. I was just recently looking for GE Electrak attachments. Several sites have information on those old mowing tractors. 

And maybe your wimpy PM could survive if you're real careful. The Electraks use a PM motor for each blade. But had problems with that  Search this forum also. Several members have posted EVmowers/tractors. I posted a photo of a 60 inch deck I did for a friend. That is the first electric deck I classify as worthy 

http://www.diyelectriccar.com/forums/showthread.php?t=45125&highlight=small+children

major


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## muns53 (Jan 13, 2011)

Well, my ideas so far have come from evalbums, including the motor I had posted about. I'm glad you alerted me to it's wimpiness. The 13HP gas motor did bog down in heavy grass, so maybe my objective should be to over-power it vs in-kind replacement. I have a msg in to DandD motors about something similar to what you have suggested in size.

What about controller? If I go with a bigger motor that is less likely to bog down and overdraw current, do you think it can just be happy on an on/off circuit?

I thought about a lithium pack with 40 AH cells. But for 48V, that's a $700 pack. It would give over 500 Ah, though, which would also be more reliable and longer-lasting. 

In order to cut cost, the other idea I had was to use the same motor/pack/etc in both the tractor and the snowblower. It would mean reconfiguring it at the start of each season, but would it would not be a difficult swap once I did it the first time.


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## major (Apr 4, 2008)

Hi muns,


muns53 said:


> The 13HP gas motor did bog down in heavy grass, so maybe my objective should be to over-power it vs in-kind replacement. I have a msg in to DandD motors about something similar to what you have suggested in size.


There you go  You bog down that PM motor like that and it will smoke the brushes and comm real quick. D&D is the size and type motor I think could serve you well. They make a variety of flavors.



> What about controller?


Yes. That is a question. You might be able to get away without one if you could find a compound wound motor. It would then have a defined no load RPM (like a PM) and great overload capability (unlike a PM). Compound motors are often used for pump drives on forklifts and sometimes on old floor sweepers. Pump motors typically have female splined shafts which are a bitch to couple.

Barring that, and otherwise, I would go with a separately excited (SepEx) motor and matching controller. These may be difficult to find. I think some of the EV parts vendors sell kits which are pre tuned. Or many golf carts now use SepEx. But golf cart motors typically come without drive end (DE) bearings and brackets to mate to an axle.

Series motors would need a controller for a couple of reasons. These are most common for EVs. The series motor has an infinite no load speed, so you can't idle at full voltage and engage belts and such. And you need an instant shut down if a belt were to break. Otherwise, the motor will overspeed to destruction. 



> If I go with a bigger motor that is less likely to bog down and overdraw current, do you think it can just be happy on an on/off circuit?


With any of these wound field motors, if you hit the clump of tall wet grass, it will try to bog, meaning the motor load will increase. But assuming you have battery capability, 400A at 40V is 16kW so you're looking at near 16hp. Likely it will power thru, or slip on the belt, or even if it does stall, you can shut down and clear the deck without sacrificing the motor. 

I used 400A because it is a common current limit for controllers of this type. Even without a controller, a wound field motor would go this high, or higher when overloaded. A wound field motor could go higher in current on an overload for a few seconds without damage, but that is pushing your luck if you ask me. I'm inclined to push you towards a controller. A controller will also current limit on start up. Without that, every start draws a huge current spike which isn't real good for the system.



> I thought about a lithium pack with 40 AH cells. But for 48V, that's a $700 pack. It would give over 500 Ah, though, which would also be more reliable and longer-lasting.


I don't understand 500Ah  Cells in series don't add Ah. 1 or 2 or 14 40Ah cells in series is still 40Ah. A pack of 14 40Ah cells would be nice. You can use most of the 40Ah with Lithium. But even then you're looking at an average of about 2 hp for an hour. Your typical "cheap" Lithium cell may be good for 3C continuous discharge or 120A for the 40Ah cells. That puts you into the 5 hp average which is about right for such a motor, but would drain the battery in 20 minutes. 

If you treat them right, Lithium should serve you for 3 to 5 times longer than Pb batteries w/r/t cycle and calendar life. Also put a lot less stress on your vehicle w/r/t weight & size for a given stored energy.



> In order to cut cost, the other idea I had was to use the same motor/pack/etc in both the tractor and the snowblower. It would mean reconfiguring it at the start of each season, but would it would not be a difficult swap once I did it the first time.


I like that idea 

Regards,

major


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## major (Apr 4, 2008)

major said:


> You might be able to get away without one if you could find a compound wound motor. It would then have a defined no load RPM (like a PM) and great overload capability (unlike a PM). Compound motors are often used for pump drives on forklifts and sometimes on old floor sweepers.












Here you see a 7.2" diameter compound wound motor belt driving 3 blades without a controller. This is a beast of a deck. I think it was intended for an 18 hp gas engine. Tony actually runs his tractor (Electrak which has a separate drive motor) from a generator instead of batteries. So the generator is current limiting. But we have run this deck on batteries and it did well at least for a few cuts.


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## gor (Nov 25, 2009)

~100 min mower (ztr, 42-62'', 4blades deck)
not too slow - 9mph
funny "adjustable" residential deck 
joystick control (wheelchair's) - also funny, but might work better than levers (or pedal) on the bumps...
p.s. funny swing-out armrests would allow him to bail-out in case of rollover danger when with over-the lap levers - you trapped on your seat....

32-40 hp - guys, you think time for e-mower to chase and beat big boys in 1-2 h mowing (like residential) department?

http://www.meangreenproducts.com/meangreenspecs.html


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## major (Apr 4, 2008)

gor said:


> 32-40 hp - guys, you think time for e-mower to chase and beat big boys in 1-2 h mowing (like residential) department?


All listed were 36V mowers. So gor, you really think they have 1000A systems?


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## gor (Nov 25, 2009)

major said:


> All listed were 36V mowers. So gor, you really think they have 1000A systems?


yes, really. it's combined power - wheels and blades(deck)
36v x 4x250=36 000; take 300a for effy; 
for ztr - 2mt wheels; 3 - deck 
5 x 36 x 250 = 5 x 9000 =45 kw; x o.85effy= 38.25


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## Dennis (Feb 25, 2008)

muns53 said:


> Hello,
> 
> I've been a member for a while and have read a lot of great stuff on this forum. I've also looked through several evalbums - very inspirational! My original intention was to work on an EV minivan conversion, then I thought about a Smyth Performance (Jetta converted to kit car) EV conversion. But with very little practical experience, I realize I need to start small and work into it.
> 
> ...


A 9 HP Sepex motor would do the job without being damaged. The bog down is from gas engines having poor torque performance vs load. The Sepex will not bog down near as much as your 13 HP gas engine and the 13 HP rating is mostly to account for the poor performance of the gas engine, so a 9 HP electric should be a good replacement. 

The motor to use is a ES-84C-70 SepEX model that is rated at 9 HP at 48 volts. If you think what I tell is you wrong then you can contact D&D here: http://www.ddmotorsystems.com/contact.shtml. Not only would they tell you that the 9 HP motor WILL WORK, but they will also correctly specify the SepEX controller that has the field map pre-programmed into the AXE controllers they sale also. So you get the controller and motor from them.

Also, since you plan to have the motor run at one speed then you can program the AXE controller in "pump" mode which goes to 100% motor speed when key on power is detected without the need for a speed control device input device.


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## JRP3 (Mar 7, 2008)

Also check with Carl at EVDrives.com He sells D&D and Alltrax, and sometimes has used parts available.


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## muns53 (Jan 13, 2011)

Dennis and JRP3 thanks, I'll do that! I had inquired at evdrives about the ME1004, I'll ask about the D&D motor, too.

The specs on that motor are 25 ftlb tourque at 2300rpm - nearly matching the gas motor - 22.9 ftlbs at 2700rmp. Thanks!


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## muns53 (Jan 13, 2011)

Major - more great feedback, thank you again.



major said:


> I don't understand 500Ah  Cells in series don't add Ah. 1 or 2 or 14 40Ah cells in series is still 40Ah. A pack of 14 40Ah cells would be nice.


Dangit.  I thought I was being clever. Yes, of course you're right, the amp-hours don't combine up because they aren't in parallel.


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## muns53 (Jan 13, 2011)

gor - 

I saw that one and one other production/oem zero-turn electric mower. The joystick is very cool, unfortunately way to much money than I want to spend on a mower, which is why I am trying to work out a solution to converting what I have.


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## muns53 (Jan 13, 2011)

Okay, for this application, what do you guys think about a D&D ES-10E-33 with a DCX-500 controller?


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## muns53 (Jan 13, 2011)

Further brainstorming...

How about using the same motor/controller/pack for a variety of equipment/vehicles (ie: tractor, snowblower, go-kart, ATV, etc.). Generally, only one is going to be used at a time. The only permanent hardware required on each vehicle would be the contactor, a motor mounting plate and some wiring.

The 48V battery pack could be housed in a small, compact, rugged, low-profile, two-wheel, towable cart. It could hold 14 x 120ah or 180ah LifePO4 batteries in it, giving each vehicle a really good range. The charger could be installed into the cart for easy plug-in to a household outlet. 

Simply swap in the motor, attach the wiring and attach the battery cart and away you go...


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## JRP3 (Mar 7, 2008)

That sounds like a reasonable way to get the most bang for your buck but I'm not sure how a trailer is going to work for a snow blower.


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## muns53 (Jan 13, 2011)

JRP - I'm thinking a very small box - max size 12" high, 24" wide and 14" deep - on a simple greased-bearing axle with rugged wheels. Might have to extend the handles on the snowblower to fit behind/under it.


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## JRP3 (Mar 7, 2008)

Unless it has a suspension including shocks it may not do too well behind the go-kart or ATV either if they move at any speed over uneven ground.


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