It's a 1980s garden tractor. Originally 16hp kohler engine on a hydrostatic transmission. Mostly for mowing and snow blowing, but I also have a wood chipper, 48" tiller, and several ground-engaging tools.
Hydrostatic transmission will probably turn pretty hard if you are using it still.... but you may not be.
The drive motor is 48v 1800w, mated to the original 30:1 gear reduction, which is more than enough power to move whatever I need.
Is the drive motor to be direct drive to the rear, eliminating the hydrostat? I am going to say that you will still sometimes need more than 1800 watts! just puttering along, you won't. But you are bound to sometime need some grunt to get out of mud, or pull a trailer, or even for when you pull that 48" tiller through the garden! That has to pull decently hard when you are in loose dirt and dragging a 48" tiller!
For a reference point on this, I converted a small 4wheeler to battery for my boys. I used a
2,000 EDIT*1,800 watt 48V motor off Amazon. I am currently running it off 2x Dewalt 60V FlexVolt batteries, so the motor is likely actually being overpowered vs. it's rating. I can't personally drive the 4wheeler (I'm 175lbs) because it doesn't have enough oomph to get me going, and I burned up the original 1800 watt 48V speed controller! (EDIT* now replaced with a 2,000 watt controller.) Gearing-wise, it goes ~18mph, so not geared way high. It won't even go through a hay field well with only a kid on it!
The power takeoff motor is 48v 2000w, and that powers just one implement at a time.
I doubt that will run your tiller!
Electric motors are so much more efficient than ICE, so you can't really compare kW to HP straight across. GE actually made a 36v garden tractor starting in the 1960s, that even had a front end loader and forklift attachment options. Some are still running today.
@MisterSandals reference 746W/hp above. I know you can't just directly reference that, but where the electric motors shine is instant torque! You still need X torque to run X amount of load. And your 2,000w + 1,800w =3800w total. That is only equivalent to about 5HP to replace your original 16HP ICE engine! That's only 1/3!
Not trying to rain on your parade, as I love playing with conversions! But just telling you what I have seen....