Presumably this is not the case or some smart fellow at John Deere would have already invented it.
Look up "LeTourneau", these guys have been making diesel electric equipment since just after WWII, mostly for forestry and mining, though there was also that "land train" thing. You'll notice the engine compartments on their machines are still plenty big. The best way to think of a straight non-battery (or flywheel, hydraulic accumulator, air compressor, or whatever other energy storage you might use) diesel-electric is that it doesn't replace the engine, it replaces the transmission and driveline. The raw power to start with (and the fuel consumption) will be about the same. You gain a few % on efficiency, wear and tear, and operating costs.
What batteries allow you to do is to take less output over a longer period of time and release it in short bursts. Also, a car operating at steady speed doesn't need nearly as much power as it takes to get it up there, which makes the battery setups a good match. For a constant heavy pull, you're out of the area where the batteries do well. And without the batteries, you still need all that power available at once--regardless if it's gears, a hydrostat, or a generator and traction motor in between the engine and tires.
For just running light errands such as moving wagons around, yeah it might make sense--so would having a smaller more efficient machine around to do those errands. For running any sort of powered implement (mower, tiller) or ground engaging tool (plow, harrow) not so much.
The tractor I see most used to do an electric conversion is an Allis G. Before conversion, this tractor puts out about 8hp (drawbar, 10 belt) stock, and is mostly used for cultivating...pretty light duty, and not a bad matchup for electric.
If you just need to carry yourself and a few tools around, how about a battery golf cart? If it will make you feel better, you can get ag lugs for them...
