Enough Power?
Some people have asked whether the electric motor we used for this tractor is strong enough... It is for us, however, it would NOT be difficult for you to bump up to the next size in motor. In fact, we machined the plates motor housing to fit the bigger motor, You'll just have to change some of the bearing and bushing sizes. (for example, the shaft on our electric motor was 7/8", so.. the bushing we bought was 7/8's inches... on the larger motor, the shaft is 1", so... obviously you would purchase a 1" bushing... your machinist needs to adjust their work to accomodate these changes.)

I have now TWO tractors running to the specifications explained in this document and I've never wished for any more power. Our first electric tractor is now three years old.

We do have a lighter sandy loam on 1/2 the farm and then a river-bottom silt-loam on the bottom half. We also have 4 foot wide beds which we use sweeps and a basket weeder on... I've never noticed any hesitation or lack for power, and I DID notice it when we had the gasoline engine on our original tractor.

Maybe the gas engine was poorly tuned though, but I feel sure that the net power I am getting off this electric machine is MORE than the original gasoline version that we used for 2 summers before converting it. If you have a heavy clay soil and cultivate 6 feet of bed at a time, then maybe this would be too small for you and you should jump up to the next size, obviously I can't speak from experience.

Power Update: We attached five six-inch wide goosefoot cultivators to the tractor, sunk them 4 inches deep into the ground and drove fast back and forth on 300' rows with no lack of power. Although our soil may be lighter than some, this is MUCH deeper than one would normally use for cultivation. I was moving a LOT of dirt. Certainly I could hear that the motor was working harder than normal, but... I could still go as fast as I wanted to in third gear. I just can't imagine a situation that would call for a largr motor.

How many batteries?
On the question of batteries, we have a 48 volt system. On one tractor we have four 12-volt deep cycle batteries, on the other tractor we have six 8-volt batteries. Though both end up with 48 volts, because there is more mass associated with the 8 volt batteries (and 50% higher cost) they will allow us to run the tractor about 50% longer on a given charge.
Interesting to note that niether tractor has ever run low on batteries if they started out fully charged that morning.

On one charge we've seeded dozens of 400' beds with our 4-row Planet Jr. and not noticed any loss of power.... We've never tried to run it out... I don't know that we have enough acreage to do so even if we wanted to. Seeding doesn't take a lot of power.
In regards to cultivation (which requires more battery power because you are moving more soil) I don't think I've ever tried to cultivated more than about 2/3-3/4 of an acre between charges... We run a CSA farm, so everything is growing at different times in different successions. I don't know how many acres I COULD cultivate between charges... or if I am already unknowingly bumping up against the limits... If we had a heavier soil it would probably use up the batteries faster. Buying the six 8 volt batteries wouldn't be that much more expensive than the four 12 volts, and we estimate that they should give us almost 50% longer running time. Base it on your farm size.
we are planning on doing a lot more larger areas of stale seed bedding with the electric tractors this year, so by August perhaps I'll be able to post a better value for exacty how many acres I can basket weed (hopefully with side sweeps) on one charge. It should be a good test, because we do really fly along with the basket weeders which I assume uses up a good bit of power, and we'll be going through some of the heaviest soil areas on the farm.

What, no clutch?
We disengaged the clutch, because unlike with a gas motor, when you stop the tractor you are also stopping the motor. We don't have any problems changing gears UNLESS we inadvertently leave a LITTLE power running! That is, we didn't turn the accelerator all the way off, so there isn't enough power to move the tractor, but there is enough to lock the gears up.
Obviously, the solution is simple. When we try to change gears, we notice that they don't easily change, and we just turn the accelerator all the way off and then they move easily.

What gear should I use?
Electric motors have very different (BETTER for farming!) torque curves than your original gasoline Allis Chalmers "G" engine. Don't let it make you lazy!! Although you can crawl along in third gear at 1/10th mph, you'll use up a lot of battery juice and have to recharge MUCH more quickly. So... remember to shift down for slow jobs even when you don't HAVE to.

If you have an amp-meter, you'll be able to see graphically what gears are most efficient battery-wise for whatever tasks. But even if you don't opt for a meter, you can easily apply common sense. Just don't be sloppy and forget to change gears just because you don't have to!