A little background;
After moving from the city to a small acreage, we started looking for a small garden tractor. In 2019 a Case 448 with mower, tiller and snow thrower attachments came up for sale. Without knowing anything about these tractors we purchased and basically that was it, I was hooked.
Since then, we picked up two more Case tractors both 444 models. The 448 is still our main tractor, the Onan 18hp runs so smooth and other than regular maintenance it’s been problem free, fantastic machine. As for the 444 tractors, both were older units (pre 1976) in working order but not quite in the same running condition as the 448 but still great machines.
At this point I decided to combine my passion for these tractors with my interest in electric vehicles…It seemed a natural fit with the hydraulic drive of the Case design and simply replacing the internal combustion engine with an electric motor. However, there were a few other considerations not initially apparent…Anyway this is how it went down (and apology for lack of pics and detail throughout the process):
The Case 448 (pride and joy):
The Case 444 (to be converted to EV, the other for parts as required):
Step 1 – Tear down and clean:
Step 2 – Painting of individual parts. For this I used (thank you so much from others in this forum) Dupli-Color Chevrolet Orange-Red DE1607. For the complimentary color I went with black rather than the “desert sunset” mostly due to availability (I get this isn’t everyone’s cup of tea). However, the fact I’m kinda butchering the original design by removing the combustion engine anyway, what’s one more change…
Step 3 – Rebuild:
Note at this point I decided to replace the rear tires with: BKT model: TR144 and the front tires with Carlisle Super Lug model: 5100969:
Step 4 – Now for the electric motor:
This system is designed around 48V only because I already had some batteries around from another project. Designed using a LiFePo4 battery bank for longevity reasons (they just handle way more charge cycles than other battery materials). The bank is 48VDC, 51Ah (but expandable). The motor is 10kW which should equate to the original 14hp Kohler combustion engine:
Next step coming soon…I'm just finishing up the motor mount to couple with the pump, battery box, and working on the electric harness at the moment.
<UPDATE>
Got a first coat of paint on the hood, decals on the way:
Winter has really set in around here and without an adequate heated space to work on the tractor I’m looking into the battery box / on board charging portion.
So for the battery storage I figured take advantage of the fact that it’s going to be heavy (regardless how many batteries I end up with). My goal here is to be able to attach the battery box to the rear sleeve hitch when using the front blade in winter and attach to the front end of the tractor when using the tiller in summer. As a starting point I found a commercial box designed for dual 8D batteries. Not the type I’m using but the dimensions seemed to work out nice (bonus that it has slots to run the cables):
Next I’ll look at making a heavy duty housing for this box that mates with both ends of the tractor.
My tractor wiring harness will have connectors at both the front and the back so the battery box can be easily connected in both configurations. Earlier I mentioned the system was designed using 48V only because I already had couple of these batteries. These lithium iron phosphate batteries have built in electronics where I’m not comfortable connecting them in series to increase the voltage, not to mention it would add complexity to the charging process. I don’t have an issue with connecting in parallel to increase Amp hours. Having said that, given the choice I’d have gone with a 72V, or ideally 96V setup. The issue with lower voltage is the massive current draw (couple hundred amps), I’m using 1/0 AWG between the battery box and the motor controller with some very large connectors. I guess the flip side is cost, it seems to me the higher the system voltage you pay more for components…
When it comes to charging this beast, I didn’t want to be pulling out the individual batteries to charge. I also didn’t want the hassle of connecting a charger all the time. The plan is to have an on-board charger. I haven’t selected the charger yet and will have to wait until I determine the Ah rating of the battery bank. I did however install the power entry so a regular extension cord will power the charger:
Note both the battery box and power entry I found at
NOCO
<UPDATE>
Wanted to add an electric fan, picked up a 6.6"x 6" (2" depth), 48VDC, 17W with decent CFM. I mounted it with vibration dampers and hoping it doesn't make too much noise...Planning to control it on / off based on hydraulic fluid temperature.