Kriss Motors Electric Conversions


The Porsche 356 reflects the mechanical age of the 1950s. Analog measurements are displayed in classic dashboard instrumentation. The lithium 356 re-purposes these gauges to retain the period-correct appearance with new electric operating information.

Each gauge presents its own challenges. For example, electric pulses which drive the tachometer must be generated by a magnetic sensor that is triggered by small magnets on the flywheel.

  Magnetic sensor converts motor RPMs

A custom Hall Effect sensor is installed to provide accurate “fuel level” information. In this case, of course, empty and full describe the battery pack state of charge.

The original oil temperature gauge connects to a controller heat sink temperature sensor instead.

In addition, two digital gauges that display motor and controller data are located under the dash.

  Speedster dash gauges re-purposed for EV operation (digital motor/controller gauges at lower left)

The Cars

Porsche 356 Speedster

The iconic Porsche Speedster proved to be an excellent EV conversion candidate due to its low weight, relatively simple design, and ample front/rear compartments for mounting pristmatic lithium battery cells. Weight distribution was improved over the original rear engine configuration with better acceleration and overall performance.

Saab Sonett

The unusual fiberglass Sonett, originally powered by a Ford V4 engine, combines a low center of gravity and front wheel drive, optimal for our high performance EV conversion. Without the need to accomodate a long drive train, the space behind the two seats was used for additional batteries. The original four-speed transmission remains intact along with the braking system.