Fomenting Revolt

Ben Nelson

Ben Nelson with an Open Revolt 500 amp motor controller

Much has been made of the so-called pay back period for hybrid and electric cars, that is, the time it takes your fuel savings to recover the higher price you paid for the car.

Ben Nelson of Oconomowoc, Wis., has looked at those numbers, too, and agrees that paying $30,000 or more for an electric car doesn’t add up.

“It doesn’t make a lot of sense, you won’t save enough gas.  We’re too quick to call in a professional, be it a plumber or an electrician,” he says.  “I said the heck with that.”

With that, he set out to build his own electric car.

Nelson’s 1996 Geo Metro is his second electric vehicle project. His first, a Kawasaki motorcycle that he converted to electric power in 2007, was successful enough for him to try his hand at a larger, more challenging endeavor.

Ben Nelson

This is how you refuel the Electro Metro – 110volt only

For this project, he bought a Metro for $500 and then proceeded to remove all the mechanical components that he wouldn’t need, including the engine, the cooling system, fuel system and the clutch. He sold those pieces for $550 and was $50 ahead before he began the process of electrifying the car.  There’s your pay back period.

From the outside, the Metro doesn’t look any different unless you flip open the fuel filler door and see an electrical plug instead of a gasoline port.  Inside, the rear seat back appears normal but a carpeted board sits where the seat cushion once resided.  Underneath the board and in the rear cargo area reside a bank of batteries storing the “fuel” for the Electro Metro.  Nelson had originally left the rear area open for battery storage but later decided that the car should seat four, at least nominally, so replaced the seat back and let back seat passengers sit atop some of the batteries.

Under the hood

Under the hood of the Electro Metro. The motor controller is out of the vehicle for testing.

Under the hood the sizeable electric motor sits low between the front wheels with heavy cables and electrical boxes lying above it.  Nelson added a vacuum reservoir on the firewall for the power brake system along with a small electric pump to pressurize the reservoir on start up.

All of the components to build his “Electro Metro” were purchased second hand including the Nissan fork lift motor, which he bought for $50, and a dozen deep-cycle 12-volt batteries, which he purchased as salvage for $12 each. The most expensive item was the Curtis 1209 controller which regulates the amount of current going to the electric motor and, in turn, controls the vehicle speed.

Battery tray

Some batteries lie under the rear seat, more are in the cargo area.

All told, Nelson initially invested about $1,300 for an electric car that is quite serviceable and cheap to drive. He has driven it up to 73 mph and in urban driving can travel about 30 to 40 miles on a single charge.  The car remains a work in progress and he has added a number of upgrades since it was first made roadworthy.

One of the most expensive components in the project was the DC motor controller and Nelson was frustrated by the fact that not only are the devices expensive, but often come as sealed units making repairs or upgrades difficult.

“If you can’t fix something yourself, how do you own it?” he asks.  “If you build it, you can fix it.”

So began the Open Revolt project.  Nelson has been involved with the Web-based development of a do-it-yourself controller as an open source project.  Numerous contributors, including electrical engineers, have added their expertise to the design of the 500 and 1000 amp “Cougar” controllers and the schematics and parts lists are now freely available to anyone interested in building one for his or her own EV project.

Nelson’s next project is a biodiesel/electric hybrid conversion of a Chevy S-10 pickup truck.  He already has acquired the S-10,  a diesel engine from Mercedes 240D and an electric motor from a junked fork lift.  A badly broken ankle, the result of an accident on his electric motorcycle, has temporarily suspended work on that project.

Nelson says that before starting these projects he had never worked on cars before, other than performing oil changes.  When talking about the work he’s done he tends to downplay his own skills and says that if he can do this, anyone can.  Perhaps so, but this sort of work does require a fairly high level of knowledge and skill, not to mention access to tools and materials.  Nelson got considerable support from other electric car builders in the Milwaukee area.  Initially they met in the garage of one of the hobbyists but have since moved to the Milwaukee Makers Space, giving them more access to the tools and expertise that other users can offer.

With two successful electrification projects on the road, Nelson has made it his mission to help others build their own electric cars and motorcycles.  To that end, he has produced how-to videos giving step by step instructions for the would-be do-it-yourselfer.  Those videos are available for purchase at

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