Nick Kirkby

I recently exchanged $500 for a 1980 Jet Industries Electravan 750 pickup truck.

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Sans batteries and title, and last registered in ‘95, there wasn’t much to it.

This is a production EV straight out of the year 1980.  To make this vehicle, Jet Industries bought a new Ford Courier pickup truck, pulled and sold the internal combustion engine, and dropped in a big brushed motor and SCR-based controller produced by GE.  The advertised power when this thing was loaded with over 1000 lbs of lead acid battery was 30 HP at 2800 RPM.

click to enlarge the spec sheet for the Jet Industries lineup.  it is a large image

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Finding Some (real?) Power

my buddy Tim had a gasoline backup generator with a blown out spark plug that he got from a friend of his.

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Ouch.  The thing wouldn’t turn over and the spark plug was long gone.  The threads were chewed up and it felt like there was something wedged up inside the cylinder head that was hitting the piston as it approached TDC.

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So I stripped it down, cleaned out the spark plug threads from the inside with a spark plug tap, and retrieved the chunks of cylinder head that had fallen down into the combustion chamber.  I was glad it was just chunks of loose junk and not damage to the valves.

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I chewed away some of the crusty blowout crater with a rasp in a rotary tool.  With a fresh metal surface, I dropped in some JB weld, smooshing it to make a nice flat sealing surface for the new spark plug.  I ran a lubed up spark plug tap through the half cured JB weld from the inside to try to get it to take the shape of the undamaged head.

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I installed a fresh plug.  It would only run on ether (starting spray), so I pulled and cleaned the carburetor.  After that it ran just fine.  Everything seems to be holding up even after a few hours of running.  With a working generator, it was on to the next step of

Still Loving The Prius Inverter/Converter assembly

did you know you can get tens of kilowatts of versatile power converter with automotive reliability from ebay for $125 shipped?  Consider purchasing a second generation (2004-2009) prius inverter.

I already love the prius brick (where brick is shorthand for the inverter/converter assembly), but to get to know it better, I laid out a board to connect all of its I/O to a microcontroller which reads the outputs and feeds the inputs.  The microcontroller is an STM32F411RE on a Nucleo development board (same as the derpbike project)

and less than a week after layout, the boards that I purchased arrived.  Cost including shipping: $80.  my friend Muffin reminds me that custom T-shirts, business cards, and PCBs are all produced in low volumes, per customer specification.  printing is amazing!

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This PCB has a breakaway chunk for attaching a DB37 connector the Prius inverter/converter harness.

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The rest of the board contains TC4478 quad gate drivers to level shift the digital outputs and some resistor dividers to buffer the inputs.   It sits on top of that nucleo dev board, inside a box embedded in the dashboard.  A DB37 cable goes to the inverter, and a DB9 goes to the throttle and GPIO.

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Power electrostuff Layout

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I’m using the generator side of the prius inverter as a bridge rectifier.  That makes 220VAC from the generator into about 350V DC on the inverter bus.  The numbers are all pretty handwavey because the bus voltage sags way down when the motor draws a lot of current.  I’m using a single leg of the motor side 3 phase bridge to drive the big “30 HP” GE series wound brushed motor.

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A single leg on the motor side is good for 400A until the inverter goes into overcurrent protection and opens both high and low side switches.  The generator side hits overcurrent protection at 200A on a phase.

I am driving the motor with a single leg of the motor-side bridge right now.

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The other motor wire is connected to bus negative.

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I hooked up a long extension cord to the generator side of the prius brick.  It plugs into the 5kW gasoline backup generator for now.  But it will happily guzzle any arbitrary AC or DC source (<=600V) that can fit in the bed of the truck/can be parked next to.

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here’s the generator tucked away in the back.  Yup, no one will ever know we’re rollin’ coal.

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for the throttle, I’m using a potentiometer inside a box.  It came with the crufty EV detritus scattered around the inside of the vehicle.  Works well.  It has a nice little limit switch at one end of its travel.  I use the state of that switch to disable the motor side bridge.

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Somewhere in the past week, I did some _real _automotive work and replaced the seized front brake calipers.

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yup seems to run.

you may be thinking: lol why stickshift in an EV?  I was raised in the church of stickshift transmissions so at least it’s got sentimental value for me.  my best guesses are:

-controller doesn’t need reverse (maybe a big plus with derpy mid 70s power electronics)

-allows the (now very outdated) motor to run in a smaller speed range.

If we ever make it back east to the land of milk, honey, and copious EV cruft and flotsam that is N52 at MIT, then perhaps it will be appropriate to speed test this big GE series wound motor to redline and beyond.  Until then, it’s gotta stay intact.

EREVPZEV, or SULEV?

Its current classification is NOPEV:  NOxious Partially Electric Vehicle

nextup: legal vehicle, more power, data logging.