1973 Porsche 914. This car had 146,432 miles on it before the initial conversion work. Since then, it was driven approximately 3,552 miles while lead acid powered. And driven 2000 miles after the lithium battery pack was installed.
New in 2011, this 9" ADC/AMD motor was customized to handle higher voltage and current by our friend Jim Husted at "Hi Torque Electric".
Trans-axle is a 5 speed Porsche 901, with internal bracing by motor Meister Inc.
With the power this car has, it's no surprise that a CV joint failed during initial drive tests. New half-shafts/CV's (intended for V8 conversions) were installed and have held up well.
The common clutch slip issues that powerful conversions often experience, was solved with a KEP (Kennedy Engineered Products Inc) stage III double disk clutch and a new lightened flywheel. The flywheel has no ring gear since a starter motor is not needed. It should be noted that this is the first double disk clutch that KEP has made for a 914.
A new High Voltage Zilla 2,000 Amp controller. Along with the controller change, bigger fuses, a new hairball and 4/0 motor cables.
(102) CALB 100Ah, 3.20 Volt, LiFePO4 cells. An estimated battery weight of 720lbs.
This 32.64kW pack was selected after capacity testing and comparing it pros and cons vs. Thunder Sky, headway, and a few other brands. 3D CAD was highly leveraged to model various cell sizes, configurations and containment. This quantity, type and size of cells was selected for a number of reasons. Pack fit, voltage, capacity and in part, due to their higher peak current output (as opposed to Thunder Sky), while also being relatively safe and affordable. New boxes & lids were designed by SHIFT EV LLC, and fabricated by Hot-Rod builder Mike Asbahr at Benchmark Fab & Finish.
Notice the slick handles for placing pre assembled sub-packs into hard to reach places.
326.4 Volts (nominal). Balanced, finish charge turns off at 375V.
Elcon 6kW LiFePo4. That's right, 6kw! Theoretical charge time of a "dead" pack is 5.44hrs. Due to reduced current at finish charge and other factors, reality is a little longer. Typical driving resulted in a charge time, about twice as long as we spent driving. Not bad by today’s standards.
This charger does not have an external profile selection button to worry about accessing. However, visibility to its charge-status LED is important. Cracking the seal (and warranty) to re-locate it by wire was not appealing. So we instead used a fiber optic "light-pipe" (the silver cord pictured) to route the light emitted, to the more visible charge connector/inlet area. This allowed us to mount the charger remotely under the front-most battery box.
It's four cooling fans and the clearance for cooling air flow had no problem with warming up, only slightly warm to the touch after hours of charging at full current.
Two unmodified blow dryers (except for the cord) were installed in the original ICE to SLA EV conversion.
Pack V (for both) is switched by a 12V Kilovac LEV200A4ANA Relay. The relay is switched on by a micro switch. The micro switch is triggered by the stock fan lever movement shown in the picture.
Inexpensive, good easy fit, one speed, a bit loud, very effective.
|DC to DC||IOTA DLS 220-45|
Custom built dash gauges (completed in original conversion).
The E-Meter just needed a custom pre-scaler for the increased pack voltage.
New BMS over/under voltage LED.
New motor temp warning LED.
Nardi Steering wheel, rare for a 914.
New top speed unknown/untested. Prior to the upgrades described, top speed was >100mph.
So far, the controller has been limited to 1400 Motor amps (@150 motor volts). It was this setting that broke a stock CV joint. And it's at these settings that we estimated 0-60mph in about 6 seconds. More untapped power is available at the flick of a stylus. More aggressive testing is up to the owner :-)
This is a subject that naysayers like to beat up EV's with. So I'll tell it like it is, and post the detailed trip log at another time.
Range is a confident 100 Miles (160 Kilometers). Max range at 65mph of optimal conservative driving has not been tested and has many dependencies. The low voltage alarm testing test described here, was in dry weather over 2 days. Average daily temperature was 57 degrees F. During low voltage alarm testing, Neal Meyer joined rode along to capture notes. The test drive covered a total of 133 miles before we were able to force-sag the pack (by punching it up a hill) enough to set off the first low cell alarm. The alarm threshold is 2.5 volts, on any given cell.
Assuming a 100 mile range is a safe DOD to insure many life-cycles for this pack. On this trip, 110mi=83%DOD.
245 Wh/Mile This is calculated from the trip data described in the Range section above. 51mph was the average speed considering city and highway driving on that trip. Efficiency improves when driving conservatively.
Seats two adults comfortably. I could swim in the cabin space. Neal Meyer, who helped with many aspects of this project is over 6 ft tall and had plenty of headroom with the top on. If you're tall and want a great platform for a conversion, the 914 is it. Even with this high-range battery stuffed configuration, there is storage under the hood and trunk. Not quite enough for a big carry on, but probably a couple little ones and some grocery bags.
2,850 Pounds (1,295 Kilograms) as measured by digital truck scales.
Michelin, Energy Saver GREEN X, AS P185/65R15
|Conversion Cost||The conversion from SLA to LiFePO4 described (plus many touches not described) cost roughly $22k in parts and labor.|
The set of Revolution Millennium Rally Wheels are rare 15x7's, built for 914's.
Bilstein heavy duty shocks and heavy duty springs all around.
Thanks to friend Keith Cornell, who provided a circuit allowing the user to easily adjust charger current. Handy to prevent tripping circuit breakers if ever charging from a low current outlet. Also nice for servicing, such as initial low current balancing.
Replaced the AVCON inlet with a J1772 inlet. Again, thanks to Keith and my Dad, Ray Swaney assistance with the EVSE power control circuitry.
One little air bubble can cause a coolant pump to experience cavitation. When this happens, the pump motor runs and all seems normal, but even with clear lines, you can't visually confirm the coolant is flowing. If it does have a bubble, it must be disassembled to confirm or fix. To prevent the bubble issue, we added a valve stem to the top of the coolant pump. It allows easy air purging after coolant line assembly. And we now stock a nice in-line indicator (part#1752 $12.98) to allow visual confirmation that coolant is flowing.