Underway on battery power

"On downhill operations, do not allow the vehicle to reach speeds in excess of 49 mph. To do so will cause the motor armatures to rotate so fast that they will fly apart..." ----Commuter Vehicles Postal Van Operator's manual.

...Not exactly a ringing endorsement of durability. Still, it's 25 years old, and it was basically a prototype vehicle. Being as it was designed for the government, that's probably a conservative warning. I've had the van up to 57 mph with no problems and I've coasted downhill up to 65 mph. I just put it in neutral so I don't overspeed the motor.

Installing and cabling the batteries was interesting. I knew they were "in series" or a large string but I wasn't sure where the beginning and ending of the string was. Fortunately I was given a diagram that showed how. The batteries are in two banks of 6. One front, one rear.

Ok, so the batteries are installed. How do I apply power to the motor? Another advantage the Postal van had over the early Citi cars is the addition of an "accessory" or "house" battery. This single 12 volt battery powers the lights, fans, etc so you're not draining the traction pack. It also applies power to the solenoid that connects the traction pack to the motor controller. The motor controller then feeds the motor via the signal from the accelerator pedal. Simple enough except that nothing's labeled and wiring data on the van is scarce because there were so few made.

The first few tentative taps on the pedal yielded nothing until I figured out that I needed the accessory battery. I thought it was strictly for lights and comfort items. Dang....I don't have a spare 12 volt battery handy. Or do I? Well it's October now and boating season is over so I raided my boat for it's marine battery and installed it. Heck, at least it'll be charged regularly.

Once the accessory battery was installed, I put the transmission in neutral and barely tapped the pedal. I was rewarded with a smooth, quiet spin-up of the motor. It's dangerous to spin and unloaded electric motor because it can overspeed and damage itself.

Next, I noted that the motor cooling fan and all the lights worked. It appears that I'm safe for a test turn around my townhouse complex...