|Owner||Bob Dahse/ Larisa Walk|
|Owner's Other EV||2006 Catrike Road|
|Location||Winona, Minnesota US map|
|Vehicle||1979 Porsche 924 |
This was a working sports car which we bought for $1200 and drove home 50 miles. We sold the engine, cooling system, fuel system, etc. using Craigslist.
|Motor||Netgain WarP9 Series Wound DC|
Standard dual-shaft WarP9 from NetGain Motors via Grassroots EV ( WebPage ) in Ft. Pierce, FL. Westach tachometer and Hall-effect motor speed sensor is from KTA on commutator-end shaft.
|Drivetrain||1.8 liter, 4-cylinder, fuel injected Bosch K-Jetronic, 5-speed standard transaxle. Front-engine, rear drive through CV axles, independent suspension, front struts, rear torsion bars (now with coil-over-shock "helper springs").|
|Controller||Logisystems 156-AFX |
1000-amp, adjustable amp limit and ramp, 144 to 156-volt. DC fan cooled. Via Grassroots EV.
|Batteries||12 Deka Dominator, 12.80 Volt, Lead-Acid, Gel|
These were sold at a local "Fleet Farm" store as "Resolute Gel Supremes" for $150 each, minus a quantity discount. The higher voltage is nice and the cycle life is three times that of AGMs or flooded cells.
|System Voltage||144 Volts|
|Charger||Quick Charge OP144V/10A Programmable|
144-volt, 10-amp, programmable charger using "float" mode to restrict voltage for sealed, gelled-electrolyte batteries. 40 lbs. of reliable, if slow, on-board charger. From WebPage . We're also doing direct DC charging from a six-panel, 720 watt solar PV array using an Outback Flexmax60 maximum power point tracking controller. When not adding to our 12-volt household panels, or charging our 36-volt electric tractor, it charges the Porsche at 48 volts via two battery switches that break the series battery bank down into 3 parallel banks. This is a much faster, more efficient charge when we're at home. We also added shunt regulators from QuickCharge that cook off excess power from any batteries that reach full charge before the others, preventing overcharge damage when series charging.
|Heater||We just bought a high-voltage core from KTA in CA for defrosting the windshield. But mainly this car is for 3-season use with a recycled Japanese hybrid gas car (2001 Prius) as a cold-weather, long trip back-up. The batteries have AC "heat tape" beneath them to bring their range up in cold weather, but once the snowy raods are salted we park this unit and drive our 1996 Geo Metro.|
|DC/DC Converter||Iota DLS-45|
96 to 156-volt, 45-amp, 13.8 volt output. Normally this would be a 12V battery charger, but hook the AC line to 144-volt DC and you have a DC-DC converter. From Grassroots EV. We're using this along with the existing starter battery to power 12-volt loads.
|Instrumentation||Digital amp-hour meter, battery amp output, motor tachometer, battery temp, and speed/odometer. Also using a 12-position, double-pole rotary switch (DP12T) with DMM meter outputs to check individual batteries. The shunt regulators have LEDs that indicate full batteries.|
|Top Speed||100 MPH (160 KPH)|
The theoretical top speed (from www.evconvert.com) will be 101 mph in 5th gear. We'll see!! The highest we've had it is 65 mph cruising.
|Acceleration||Unknown. I'll post 0-60 figures when I can.|
|Range||50 Miles (80 Kilometers)|
50 miles at 55 mph is the theoretical range at 100% discharge (according to WebPage ). This assumes Bridgestone B381 "low rolling resistance tires, or possibly the similarly-compounded Cooper CS4, 185/70R14 Touring tires that are now installed. With our VERY hilly terrain our actual range going to Winona, MN and back home is closer to 40 miles. We are keeping the tires at maximum cold pressure of 44 psi.
|Watt Hours/Mile||200 Wh/Mile |
This is at 55 mph in 3rd gear, with 300 lbs. of driver and passenger, using theoretical power figures from WebPage .
|Seating Capacity||2, with VERY small rear seat area used up by rear battery bank, but plenty of rear deck storage under the big glass hatch with capacity for up to 500 lbs. thanks to rear "helper springs".|
|Curb Weight||2,500 Pounds (1,136 Kilograms)|
This is the initial weight. After removing the ICE components and adding batteries, motor, etc. we are closer to 2800 lbs. I need to get this thing on an actual scale at some point.
|Tires||Switched from 4 cheap, undersized, used tires to Cooper CS4 Touring, size 185/70R14.|
|Conversion Time||I ripped out the engine in late February 2009, finished it in early June after numerous fits and starts, so about 3 months of spare time.|
|Conversion Cost||Nearly $10,000, if you don't include the added infrastructure additions to our photovoltaic system ($3000) necessary to charge this thing. Details at WebPage|
|Additional Features||Magnetic and electrical field shielding (from WebPage ) will eventually be installed on rear battery bank, the power-side wiring traveling through the "floor hump", and the firewall area near the motor and controller. Thick aluminum sheeting was used under the engine compartment to improve underbody aerodynamics and to prevent wheel well splash on underhood components. Eventually we will cut away the rear deck and lower it, removing the current spare tire well, to take advantage of additional storage space where the gas tank was mounted, and to improve rear underbody aerodynamics.|
|This was A LOT easier than building our Olds Firenza hybrid back in 1992!! The motor adapter plate dimensions were carefully measured from the flywheel housing, then the adapter was ordered from EVPC in West Palm Beach ( WebPage ). Nice job, but overpriced and it took forever to get it. Steve Clunn at Grassroots EV helped me out by building the clutchless motor shaft adapter from my clutch disk. One addition to the 1st and reverse gears that really reduced the "lurch" from too much torque in a clutchless design was Steve's idea of putting a "creeper" switch next to the shifter which parallels a 1 kohm resistor in the potbox-to-controller line. This gives gentle starts and loads of speed control at low speeds. The only problem so far is voltage sag when we climb a steep, fast, and mile+ long hill on the way home from town. We've solved it so far using either an alternate longer but slower route or by downshifting to 2nd gear and keeping the RPMs up over 3500 when climbing the long fast hill. The electric heater core from KTA is now installed and works great for defrosting the windshield. This has extending the useful driving period about a month, from April through part of November, almost 8 months per year.|