The Alchemy of Otmar Ebenhoech
By Bill Moore
As legends go, Otmar Ebenhoech is both approachable and elusive. You don't have to hang around the performance EV world -- virtual or real -- very long before you start hearing references to "Otmar" this and "Otmar" that. Where high school kids and budget EVers look to "Curtis" controllers for their electric vehicles, the power-hungry, high-voltage denizens swear by -- and sometimes at -- Otmar's fabulous Zilla controllers.
In case you're an EV neophyte and aren't all that familiar with this Curtis versus Zilla debate, a controller is the electronic equivalent of the carburetor or fuel injection system on an gasoline engine. It is what controls the speed and torque of the electric motor. Curtis controllers are world renown and used in countless types of electric vehicles from wheelchairs on up.
But if you're into power and performance, then most people get on the waiting list for a Zilla. Where Curtis controllers for series wound electric motors top out at 500 amp at 96-144 volts (model 1231C), Zillas start at 1000 amps. There's even a 2000 amp model, four times the capacity of the Curtis.
Where the Curtis will get your Geo Metro electric car conversion down the road with modest acceleration and acceptable, streetwise performance, a Zilla will launch it at sub-10 second, quarter-mile track times. Zero-to-sixty goes from 12-15 seconds to 4-5, assuming you've got the balls... I mean batteries and motors to handle it.
But like many legends, Ebenhoech also cherishes his privacy; the constant interruptions of email and telephone used to keep him from perfecting his creation. So, he set up the Cafe Electric website, hired some people to handle the business of manufacturing and selling his controllers, and retreated to the seclusion of his "hidden" lair somewhere in or near Corvallis, Oregon.
It was there that I finally was able corner him for this 38-minute interview, which you can listen to using either of the two MP3 players at the top of the page, or download for playback on your favorite MP3 device.
What you'll learn is that there is as much alchemy as there is science to the creation of a reliable high voltage, high amperage controller that, as Ebenhoech explains, isn't taught in text books.