ElectroClassic EV
Classic Cars Reborn into the Electric Future

What Goes Around

At 90 years old, Penny’s dad Ralph is a genius inventor, thinker, tinkerer, and problem-solver. One of many lasting impressions Ralph made on me was an unforgettable Thanksgiving at Michael and Penny’s. My motorized couch had been stored in their garage after that year’s Burning Man. When we arrived, Ralph greeted me with a twinkle in his eye and the exact measurements of the driveway. He confirmed the motorized couch could squeeze from the garage to the street, with barely an inch clearance on either side. After dinner, we fired her up and were all treated to couch rides in the chilly night air of Pasadena. Ralph was merely thinking ahead, but it felt like he read my mind. When he mentioned his classic Triumph TR4a was slated to be electrified, it seemed like he opened a window and climbed into my brain. Count me in! Time passed, and circumstances prevented the Triumph from going electric, but a seed was planted that gave birth to this Porsche 914 EV project. Of course, Ralph takes a special interest, reads all of the blog posts and follows my progress.

When Ralph was recently in town, Michael and Penny asked if they could bring him over to see the car in person. There would be no greater privilege than to hang in my backyard with Ralph, his wife Margaret, and my closest and dearest friends. Ralph helped inspire me, and I wanted to give him an afternoon to remember. This is what I did to prepare:

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I decided this was a great opportunity to finally bring the main power circuit online. I started by connecting the main positive pack cable to the positive end terminal of the battery pack, including all of the primary wires for the DC/DC converter, pack charger, heater core, and keyswitch power. I made sure the BMS module wire was at the top of the stack, under the lockwasher.

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Next I bolted the main negative controller cable to the negative end terminal of the battery pack, along with the negative connections for the same circuits mentioned above, all of which tie in to full pack voltage.

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Now when I pop the hood, this is how the controller looks with all main and ancillary power circuits hooked up. This is the heart of the operation, and with all of the cables flexing about, it actually looks something like a heart.

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The positive leads for the auxiliary battery had been disconnected as a safeguard against accidental shorting or power drain. The small red wire on the left terminal supplies the BMS control board with a constant 12 volts of accessory power, even when the key is off. The large red wire under it ties directly to the 12 volt positive output of the DC/DC converter. This way, the converter always keeps the battery charged, and the battery pitches in if the converter’s output momentarily dips with heavy current draw – like during acceleration.

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Finally, the Anderson connector is plugged into the output of the DC/DC converter, where 115 volts from the traction pack is stepped down to 12 volts to run all of the original vehicle accessories, including lights, signals, radio, horn, wipers, washer, and the like. The big red wire that veers to the left is headed to the positive post of the auxiliary battery, and the red wire that swings to the right feeds the fuse panel for the entire car. The black wire beneath them ties directly to body ground via a threaded stud near the fan blower.

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Under the gizmo box, the 10-pin connector halves were mated, bringing the BMS online. The control board is now getting 12 volt power, and monitoring the signal loop and state-of-charge of the entire battery pack. Pulling one of the yellow wires from an individual battery module breaks the signal loop and results in the appropriate buzzer warning after 5 seconds, including the auxiliary buzzer in the cabin.

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The emergency disconnect plunger is designed so a firm push on the clown nose breaks the current path and shuts down the entire traction circuit. Only a few unkeyed accessories will then run off the auxiliary battery, including the hazard and parking lights, the interior light, and the radio. Conversely, to bring the high current battery circuit to life, the clown nose gets pulled out with a firm tug that closes the loop with a snap. Massive electrons are now ready to flow.

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So far, so good. No magic smoke has escaped. A turn of the ignition key activates the 12 volt keyswitch relay, which tells the Curtis controller to energize the main contactor with a loud click. Full pack voltage is now available to the motor, and the controller emits a faint whine, waiting for instructions. I reached into the cabin and nudged the shifter into neutral, and then turned the ignition key off. I would save the moment for Ralph and company.

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The scene had been set, and I prepared a tray of drinks and chips for my imminent guests. On arrival, they admired the restoration of the front of the house that was demolished by a van-load of drunken partiers on New Years Eve. After a brief tour of the inside, we retired to the back patio with our drinks and chatted until they demanded I unveil the Porsche. The grand moment had arrived. To see what happened, click here or on the picture above. Shouts to Michael C. for the ace camerawork.

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3 Responses to “What Goes Around”

  1. […] the dude sold it to somebody else, so I bought his GT6 instead. This is nearly the same car that Penny’s dad Ralph was going to convert, inspiring me to turn my Porsche 914 into an […]

  2. For someone who loves vintage cars, this is a very inspiring project. It’s timely and much needed in LA and anywhere really. Congratulations on figuring out everything about the conversion. Having seen your final 914, I would have to say your work is amazing. I look forward to seeing these being sold by you and to seeing your next generation. I’m putting it on my wish list!


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