My father has put me on the task of converting an old Husqvarna GT2254 riding mower to electric power.  Mostly so he doesn't lose the zero-turn in the pond behind his house. The yard is fairly big, and even with a 54" deck, requires at least 3 hours to mow normally.  The zero-turn will be used for most of the mowing, but has trouble around the pond, so he wants this one to do that job.

Yesterday, I started on my research.  While there are kits available, sorting through all the data to get the quotes seems daunting, and the popular option from Canada www.electrictractor.net is not designed for such a large mower deck.  Other options were running $1572 US, without battery packs, or required knowing things about the mower that the manufacturer and their suppliers just do not provide, or still have on record.

That said, here is what I can piece together, from available information.

1.) If your mower has a hydrostatic system, you may not need a motor controller, as the hydrostatic system provides all of the gearing and conversion from the motor to propulsion and mower deck.

2.) If you do NOT have a hydrostatic system, you may need a motor controller to enable motor speed and torque controls.

3.) A 12 or 24 Volt DC system will have a harder time keeping up than a 36VDC or even 48VDC system.  So it would likely be wisest to have a 48VDC system to keep current requirements down, and motor power up.

4.) Resources for DC motors of this type are scarce if you're used to looking for industrial motors.  Try looking for Golf Cart motors instead.

5.) Know your motor shaft design.  A keyed circular shaft is easier to find than a toothed one.  If your drive train uses pulleys, you may need to get new ones to convert your machine.

6.) A project that I found VERY useful and full of helpful information can be found at the following URL: https://ecorenovator.org/introducing-ecorider-riding-mower-electric-conversion-project/

7.) From what I gathered, the standard mower should operate at a 48VDC minimum, and be expected to have a constant load of 65A to 100A DC depending on what you're doing with the mower.

8.) You will also want to do some maintenance on all of your bearings to minimize friction.  Be it greasing or replacements, these optimizations and cleanings should decrease motor load.

9.) Horsepower: Gasoline engines do not produce torque as quickly as electric motors.  As such, they tend to be slightly oversized for the job.  At the same time, the tendency is an approximate 2:1 ratio in rating (Gas:electric) according to practicalmachinist.com, but doesn't account for the difference in RPM, just torque.  Which means that a gearbox might alter this.  -- more research needed --

10.) Batteries: Lead acid is cheaper than Lithium chemistries, but heavier and has a shorter life.  And then to do things properly, you have to match the batteries, which is not my expertise.  I'll have to do a LOT of research here, and make sure the battery packs are designed to minimize issues from this source, for safety reasons!

11.) Life per charge.  I would like to have the charge last somewhere between 45 minutes to an hour, with the mower deck running. This should provide plenty of time to mow around the pond, or pull a trailer full of wood around, if I'm lucky.

12.) Battery discharge rates may be important to discover information about before I purchase the cells.  Not to mention charging methods.  I will likely have to implement some sort of voltage monitor to verify all cells are discharging at the same rate though.

Where to go from here:

1.) I need to figure out what RPM the engine on the mower has, as well as the properties of the transaxle, and weight of the chassis.  These may provide significant information regarding what kind of motor I need.

2.) Kellycontroller.com seemed to be a really good option for finding motors and motor controllers as I did my preliminary readings.  Even better, you can program the controllers from your computer, for better control.

3.) I need to look deeper into the gas to electric power rating translations, to optimize my design.

4.) Definitely need to learn about battery pack matching and how batteries operate to help ensure safe operation.

5.) Once I get the rest of the system designed, I'll need to design the monitoring circuit.  Should be possible using an AVR, a few op-amps to offset and scale the voltages, and a transflective or reflective LCD for readout.  And then I'll have to seal them so the debris doesn't cause issues in operation.  I'll work on this AFTER I get battery research done.

6.) Charging the batteries will pose at least as much of a challenge as the battery pack itself.  So I need to look into and understand this as well.

Ignorant rough estimates, assuming new parts, no difficulties, and working from the EcoRider data:

KDZ controller (waterproof, with Regen, 300A) assembly: $487

Mars 0708 DC motor: $549

Control Cable J1: $9

Control Cable J2: $9

Batteries: Group 31, 12V Deep cycle Marine/Boat/RV batteries, 4 pcs: $121.99 ea, for $638 with taxes.

Subtotal: $1692

Not included: mechanical components or charger system.

Note: Manufacturers do NOT want you doing this for various reasons not worth discussing in this project.