# Planning - JD ZTR Mower Conversion - Need Advice



## JGZinv (Apr 12, 2011)

*Skill:* Moderate to high. Have multiple tool chests, welders, automotive & industrial experience. 
If I can't handle it a neighbor or fab shop locally probably can. No prior EV conversion experience.

*Range:* About 3 acres of farm grass (half the yard, see below).
*
Performance:* 2.5 hours would be half my yard at roughly 80% throttle, that would be acceptable, 
as I could bring it in, charge and go back out. Longer would be better of course.

*Donor:* 1997-ish John Deere F680 ZTR 60" deck, pro/turf riding mower.

*Budget:* $1800 and under. $1800 is the cost of a new gas engine.

*Time frame:* Would like to get this project started this week, the grass be growing...

*Motor/controller:* Need help here because I really don't know what to use as a starting point. (More below)


Basically I've had this mower in service for a few years now, always been 
a good rig. This last week we got it ready with new plugs, oil, filter, etc 
and the oil pump or cooler must have got plugged and she cooked herself.
We've been told already it's a loss, and a new engine is about $1800 
shipped. So I got the idea of why not skip the gas guzzling, oil slurping 
monster that it is - and go electric.

Evidently there's many other folks that have converted regular mid mount 
riding mowers, but there's next to no ZTR conversions. So here I am.










The mower uses a hydrostatic pump for each drive wheel, and those are 
belt driven off the flywheel stub shaft on the engine. The PTO is 
connected to the front of the flywheel. The 3 deck blades are belt driven. 
So the simplest idea was to try and find a electric motor with similar specs 
as the engine, and just swap over the stub shaft.

Engine specs:
Kohler 20 HP CH20S-64586
Twin Cylinder, Horizontal Shaft
Cylinder Type: Cast Iron Sleeve
Cylinder Head Style: OHV
1-1/8' x 2-25/32" Crankshaft
.25 (6mm) Keyway
Drilled & Tapped 7/16-20 UNF
12 Volt Electric Starter 
(Shift Style Solenoid)
25 Amp Stator
Oil Filter (Oil Pump)
Standard Duty Air Cleaner
Muffler: Yes
Fuel Tank: Yes
Fuel Pump: Yes
Controls: Remote
Engine Weight: 106 lbs
Engine Applications: PA-64586
Includes Flywheel Mounted Stub Shaft
(2475508-S)

Engine Pictures:
http://www.smallenginewarehouse.com/product.asp?PN=CH20S-64586&

Since I can't find information on how fast the engine spins the flywheel,
I had to pull some information from a similar motor on Kohler's website,
which states Max Power @3600 RPM hp (kW) - 20 (14.9)

I am aware of these similar threads:
http://www.diyelectriccar.com/forums/showthread.php/zero-turn-radius-electric-riding-lawn-54833.html
http://www.diyelectriccar.com/forums/showthread.php/ztr-zero-turn-ev-design-40071.html
http://www.diyelectriccar.com/forum...e-newer-hydrostatic-riding-mowerii-42533.html

Here's some pictures under the hood. The engine is ready to be removed, it's just sitting there.




















This was sort of the basic idea I had in mind. Build a battery tray behind 
the existing engine mount. Use the existing battery tray and gas tank tray 
for batteries as well. Might be able to fit more in there depending on the 
motor. Add some controls to the instrument cluster, and probably a bracket
mount for the motor itself.













So how far from crazy am I trying to get this to work within requirements, 
and what do you recommend?


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## Woodsmith (Jun 5, 2008)

Welcome to the forum.

You seemed to have done some homework so that is good.

My first thought is a SepEx motor, it won't spin to death on part throttle if a belt breaks as a series motor would. However, SepEx woud be a little harder to find and less choice in controllers.

A thought on avoiding the belt breaking risk could be to have two smaller motors directly connected to each wheel pump. Or you could re pipe the system and use a power steering pump and motor from a forklift doing away with the individual pumps.

Either way I would suggest a separate SepEx or shunt motor for the deck.

major also has an electric tractor and knows about motors and will probably tell you something better.

Motor speed and power shouldn't be a problem overall and you can probably run on 48v easily enough.


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## major (Apr 4, 2008)

Woodsmith said:


> major also has an electric tractor and knows about motors and will probably tell you something better.


Yep Woody,

I'd tell him he'll need a lot of battery. 










A 60" deck will suck a lot of amps  Ref thread http://www.diyelectriccar.com/forum...ions-deck-motor-riding-lawn-moweri-45125.html 

More later,

major


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## major (Apr 4, 2008)

JGZinv said:


> So the simplest idea was to try and find a electric motor with similar specs
> as the engine, and just swap over the stub shaft.


Hi JGZ,

Here's a thread where I discuss the merits of that approach. http://www.diyelectriccar.com/forums/showthread.php?t=56961 

Woody,

We really need to group these threads 

Regards,

major


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## gor (Nov 25, 2009)

JGZinv said:


> *Skill:* Moderate to high. Have multiple tool chests, welders, automotive & industrial experience.
> If I can't handle it a neighbor or fab shop locally probably can. No prior EV conversion experience.
> 
> *Range:* About 3 acres of farm grass (half the yard, see below).
> ...


hi, J. do you have specs on f680? weight, pumps 10cc? whellmotors displacement? drive pulleys? tires seems 20-22''?
no longer in production - cant't find specs online 
f680 parts catalog:
http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt
(no description, sizes, etc)
it was nice little mower - but slow 
20hp for 60''deck also seems pretty low, but if machine not to0 heavy... beats walk-behinds : ))))

kohler 20hp - 624cc; 90lbs (41kg)
20 hp (14.9kw) @3600;
32.7 lbs ft (44.3Nm) @2500;
and 29 lbs ft (42Nm) @3600;
http://www.kohlerengines.com/onlinecatalog/productDetail.htm?productNumber=Command PRO CH20/CH640

7mph = 100 rpm ( 24''wheels)

3600/100=1:36 reduction 

power/torque requirements w/o PTO(deck) - 45(30) dgr slope; able to lift 1/2(1/4) of its weight per wheelmotor? (going up on curbs) 

if say power requirement 10kwh (1h continuous duty, 10 kw):
31ah*3.7v=114.7wh (0.86kg) (*SLPB 78216216H cell *4 example )
x100 cells =11470wh = 11.47kwh (86kg, 189.6lbs)
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doable... but tight...


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## JGZinv (Apr 12, 2011)

Woody & major thanks for the welcome, I guess I'm looking
for a bit more direction as the indicated threads a bit vague.

I'm not sure on what the differences are between say a SepEx, series, and shunt motors for instance. Not sure if I should be looking for a forklift motor, a floor buffer motor, or something new that'll need to order...



Gor - Broke out the manual, here's both entire specs pages, and the mower deck page.

http://i32.photobucket.com/albums/d1/GuardianZinv/Mower/F6801.gif
http://i32.photobucket.com/albums/d1/GuardianZinv/Mower/F6802.gif
http://i32.photobucket.com/albums/d1/GuardianZinv/Mower/F680Deck.gif


Weight, not including the deck, I'm thinking around 650 pounds.
One source online randomly cited 1000 pounds, but I doubt it's accuracy.

Pumps, I tracked down this:
Model: PL-DGVQ-DY1X-XXXX 
Model Ref: BDP-10L-133P 
Cross Ref: AM123535 
10CC Variable Pump
Diagram: http://www.odref.com/pdf/Hydrogear/bdp-10l.pdf

Drive pulleys - Not sure what you're asking here? They are belt driven currently.

Tire info is on the spec sheets. knobby center, ribbed rears, and the deck tires, one is a solid tire (blasted nails!) and the other is still a regular tire.


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## JGZinv (Apr 12, 2011)

Well unfortunately I'll be keeping the Saudi's employed a bit longer,
ended up going with a new engine. About $1700.

Tried contacting a place up in Poland Ohio that had made an
electric ZTR back in 2006 (before Hustler). But they didn't get back
to me. 

Feel free to elaborate more on the design though if you want. This thread tops a lot of search results for ZTR mowers now, so someone will eventually
follow me in this project.

Thanks for the help.


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