Wow, so I had no idea what was going on...

So if you look at the ev100zx manual, we'd be at least talking about the same page numbers, which is drawing on page 5 and explanation on page 15.

The control circuit is energized by closing the key switch, seat switch, and moving the forward
or reverse lever to either position, and then depressing the accelerator closing the start switch. This
applies power to the control card turning on the PMT driver , which will close the selected directional
contactor and complete the circuits to the drive motor. (See elementary drawings.)
The control card then supplies a gate pulse to 2REC turning it on to a conducting state, allowing
current to flow from the battery through lC, lX, 2REC, motor field, motor armature, sensor, and
back to the battery. After lC charges, 2REC shuts off due to lack of holding current. The control card
checks that lC is charged and unlocks the gate to lREC and 5REC.
The control card then supplies a gate pulse to lREC turning it on to a conducting state, allowing
current to flow from the battery through lREC, motor field, motor armature, sensor, and back to the
battery. 5REC turns on and allows current to flow T4-T3, lC, lREC, 5REC to T4-T3. This current
charges the bottom of lC positive with respect to the battery positive bus. This charging cycle occurs
in less than l millisecond (.00l sec.) and 5REC shuts off. This charge is now stored on the capacitor
until it is time to turn off lREC.
Current continues to flow in lREC until the control card fires 2REC. When 2REC conducts,
capacitor lC discharges around the circuit composed of lC, 1X, 2REC, and lREC. This discharge
current opposes the battery current through lREC so that the resultant current is zero. With reverse
voltage across lREC, lREC is turned off. Current continues to flow in the 2REC, lC, motor and battery
loop until the capacitor (card terminal l4) is fully charged negative. This charge exceeds battery
voltage by an amount which is a function of peak motor current, and 2REC turns off. Figure l illustrates
the pulsing of current from the battery.

What a.....

Ok so maybe my explanation will be easier to understand, maybe not. When you start going forward, the current that goes to the motor is only the current created by charge leaving the cathode of the capacitor while charge enters the anode of the capacitor thus lending a positive charge to the capacitor. This current flows though 2rec, and the directional contactor and the motor, when the capacitor is charged so that it's anode, relative to it's cathode, is at full battery volts, electrons will no longer flow. because they do not flow, there is no current across 2rec. 2 rec by nature of insufficient current self opens as all thyristors do when charge stops flowing. Now the control card can tell that the cap is charged, so it triggers the gate on 1rec, and 5rec. 1 rec supplies current to the motor and 5rec, which allows current to pass through to the capacitor, which means the capacitor has equal emf acting on it, and so it wants to equalize voltage potential across it's anode and cathode, so it's going to get balanced, with charge on both sides. When this is equal, no more current can flow, and 5rec shuts itself down, thus keeping the cap charged, isolated and ready to do something very important. When you stop moving the stick forward, the truck is supposed to open that contactor, but doing so while current flows would be bad for the contactor and the motor and would create a huge spike of something across the whole electrical system that would be rough on the whole unit. So the card uses a gate pulse to activate 2rec, and that allows the cap to equalize voltage on both sides of 1rec at the same time, so that 1rec shuts itself down as no current is flowing and thyristors only stay open when there is sufficienty current...

..... I still don't know where the....half battery voltage comes from. Hahahaha.

I'm wondering if it has to do with full voltage on one side of the cap, half voltage on the other side, and then another circuit element maybe even another cap somewhere, which when not in use represents a circuit at equilibrium with no current passing through the card, just a chain of decreasing voltage across a series circuit..

Maybe its coming form the card somehow, as part of a speed control feature which is activated in error, or something like that.

I definitely need a handset. Why are these things so obscenely expensive?

Maybe I can simplify this enough that its close to the thing you tried to tell me.

The 2rec provides a slow current ramp, to prevent jolting and sparks, and a current neutralizer to shut off 1rec, and the 5rec regulates the recharging of the 2rec device. Without 5rec, 2rec would be spent after turning 1rec on and 2rec wouldn't be able to turn 1rec off nice and clean.

My traction potentiometer at least is reading the specs it seems like it should.

I gotta track down this half bat volt thing, and see if I'm leaking charge somewhere when I shouldn't be, or what's happening.

The warehouse guys had installed a bunch of extra read outs, locators, scanners etc, to the truck when it was running potato chips, and it might be that one of those wires they hacked off is connected to something that's grounding out or providing charge where it shouldnt...

I really appreciate you trying to help. I'll get this thing figured eventually!

and ummm to answer your question... I'm just unreasonably curious. My dad was a fancy scientist... so I'm sure I picked up some of the tendencies from him... but I'm just a hillbilly trying to stack.... in my barn, so I can organize all the pumps and motors and hydraulics and electronics...

I guess I'm kinda trying to teach myself to be an electric engineering designer, cause I want to..... around with autonomous farm robots, but I just read a lot, and I'm stubborn about dropping things I don't understand, so I just keep reading...and watching videos and looking up explanations on forums and MIT coursework and discussions between professional electricians or whatever... I have to until I convince myself I know what I'm talking about... but sometimes I have no... idea, which I got to find out tonight. That was fun, I think I actually have half a clue now, and uhh, couldn't have done it without you. Srsly though i've been trying to get this for 2 weeks, and for some reason you really helped me actually get it, even if you feel like you didn't do much, you should feel proud or something. Thanks for lending a hand.