Service Examples
73 Porsche 914 ColageElectric Porsche 911 on Cover of Excellence MagOur objective for this car was a reliable range of >100 miles and to design-in some impressive acceleration.
 
We converted it from sealed lead acid (SLA) batteries to LiFePO4 including Battery Management System (BMS), J1772 inlet - for EVSE charge stations, charger and all affected systems.
 
In 2011, we took our first road trip of mixed driving, including highway, city, and country hills with a mix of conservative and aggressive acceleration. At 133 miles, a 2.5V cell alarm finally triggered (under load), which was the purpose of this test (not maximum range).
 
The car is also quite quick. We've limited the Zilla 2000 Amp controller to 1,400 Motor Amps, so far... It's up to the new owner to turn it up if they're not completely satisfied with acceleration as it is!
 
This car was featured in an article called "Plug and Play: Electric 914 " in the October, 2008 issue of Excellence Magazine, prior to its conversion from lead acid to lithium.
Many skilled people/companies contributed to building this vehicle.
  • Richard Rau performed the original conversion work from internal combustion engine (ICE) to a Lead Acid powered electric.
  • Otmar Ebenhoech provided insightful guidance from systems, to the entrails of Zilla features, tips & tricks.
  • Neal Meyer, Keith Cornell, and Ray Swaney provided valuable insights, design and fabrication assistance.
  • Vehicle selection, Elephant racing suspension and Willwood brake installation by Tim Morris's crew at "German Master Tech" - Bend, Oregon.
  • Mike Asbahr at Benchmark Fab & Finish fabricated battery boxes & lids to our specifications - Corvallis, Oregon.
  • New leather interior by "Red Hot Interiors" - Bend, Oregon.
  • Paint by European Auto Body - Bend, Oregon.
Vehicle

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.

Motor

Dsc01829-sml

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".

Drive train

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.

Controller

Trunk viewDsc05518-sml

A new High Voltage Zilla 2,000 Amp controller. Along with the controller change, bigger fuses, a new hairball and 4/0 motor cables.

Batteries

LiFePO4 CALB 100Ah Cells (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.

The handles are for placing pre assembled sub-packs into hard to reach places.

System Voltage

326.4 Volts (nominal). Balanced, finish charge turns off at 375V.

Charger

charger viewsElcon 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.

Heater(s)

Easy Porsche Electric Heater

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
Instrumentation

instruments-sml

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.

Top Speed

New top speed unknown/untested. Prior to the upgrades described, top speed was >100mph.

Acceleration

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 :-)

Range

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.
The first 50 miles of the test was efficient driving and mostly highway miles at 55-65mph. After that was less conservative with higher peak speeds for another 60 miles. Traveling farther than planned, we ran out of time and had to put it away for the night. The next morning, without additional charging, the final distance of the 133 mile journey was aggressive acceleration and hill-climbs, with ~1 mile runs at 50-60, then slowing for stop signs or rolling 90 degree turns. When the low V alarm did signal, highway speeds and strong acceleration were still no problem. No worries about being stranded when the test was stopped at 133 miles. The throttle was slightly softer than with fresh batteries, but with mild acceleration driving, you wouldn't detect it.

Assuming a 100 mile range is a safe DOD to insure many life-cycles for this pack. On this trip, 110mi=83%DOD.

Watt Hours/Mile

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.

Seating Capacity

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.

Curb Weight

2,850 Pounds (1,295 Kilograms) as measured by digital truck scales.

Tires

Michelin, Energy Saver GREEN X, AS P185/65R15

Conversion Time Unimaginable
Conversion Cost The conversion from SLA to LiFePO4 described (plus many touches not described) cost roughly $22k in parts and labor.

Additional Features

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.

2011-11-19 16-44-36_251-smlReplaced the AVCON inlet with a J1772 inlet. Again, thanks to Keith and my Dad, Ray Swaney assistance with the EVSE power control circuitry.

controller coolant flow indicatorOne 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.