Convert an Old Car to a Hybrid

Back in 1979, Dave Arthur converted an Opel GT into a hybrid. In 1993, he's still going strong with conversions. MOTHER talks with Dave about the process.

  • hybrid car
    Dave Arthur shows some of the components in his modified electric motor.

  • hybrid car

Alternative-energy vehicles have been motoring through the pages of MOTHER since 1970. Our response to the energy crisis at that time took the form of a number of investigations into alcohol, ethanol, gasohol, and ultra-efficient diesel engines. But in 1979, Dave Arthurs, then of Springdale, Arkansas, came upon a design combining electric and gas engine formats that made even the billion dollar development efforts in Detroit seem like a waste of time.

Using parts that he had purchased for under $1,500, Dave designed and built an engine system for his Opel GT that could propel the car 75 miles or more on a single gallon of gas! Dave's Opel was a hybrid electric vehicle. That is, the car was driven by both an electric motor and a conventional internal combustion engine. An array of six-volt batteries provided the direct power for the electric drive, while an efficient six-horsepower (hp) lawnmower engine ran continuously to generate power for and recharge the batteries. The combination of power plants made the car amazingly versatile. The batteries alone could be used for trips of under 25 miles, but the car had an unlimited range as long as the generator engine was running and the driver didn't have a penchant for drag racing. Additionally, if the electric power plant developed a problem, the Opel could travel on the five-hp engine alone at speeds of 30 miles per hour. Dave reported that the crossbreed hookup performed so well that, initially, MOTHER'S editors were more than a bit skeptical. It was decided that the only way to effectively test the design was to build our own.

A few weeks later, we had a hybrid engine comfortably placed in a 1973 Subaru chassis. We had decided to install a slightly bigger generator engine, but our car still averaged 83.6 miles to the gallon, ran flawlessly, and emitted a minimum of pollutants as it tooled along the highway. The idea caught on like wildfire among MOTHER readers and over the course of the next year, 60,000 people asked for plans to convert their cars. As might be imagined, technology has marched along at a pretty brisk pace since 1979, and recently we were gratified to hear that Dave has been to the drawing board again, converting the engine of a 1980 Toyota pickup into an even more efficient hybrid of electric and gas formats. The results are simply better than ever. MOTHER spoke to Dave at his Fayatteville, Arkansas, home about his designs.

Some Electricity Basics  

If it has been more than a few years since physics class, and Dave's talk of amps and volts leaves you in the dark, here's a short refresher. Dynamic electricity is simply electricity—a number of freed electrons, or negatively charged atomic particles—set in motion. An amp, or ampere, is a measure of the number of electrons flowing through a conductor (in most cases, a copper wire). In other words, an amp is a measurement of the volume of electricity. When the electrons travel through the wire, they encounter resistance from other atoms and particles. An ohm is a measure of this resistance. A volt is a measure of the force of the electrical flow which causes one ampere of electricity to travel through one ohm of resistance. A nine-volt battery, for instance, is capable of generating a flow of nine amperes of electricity through a one-ohm conducting wire.

How has the format of the hybrid vehicle changed since 1979? 

Although there have been quite a few developments in combustion engine design over the last decade, battery technology has taken the real leap. That's fortunate for the hybrid car since the electric engine provides the lion's share of the motivation. Basically, batteries are getting lighter and more powerful. Six-volt batteries were the only types suitable for my purposes back in the '70s. Have you ever seen one of those old six-volt batteries? They're monsters. I had to use six to generate the appropriate current, and at 75 pounds apiece, a very significant amount of the batteries' energy was spent hauling itself around. The new models weigh precisely the same but produce twice as much power. As a result, cruising range has now been extended, as has as average cruising speed. The batteries I use are deep-cycle with a cold-cranking power of 1,314 amps. I highly recommend a 36-volt circuit, so you'll need at least three of these 12-volt batteries. Most cars will draw 150-200 amps at 45 mph. When looking for a battery, compare the reserve capacity and the number of plates per battery. A high number indicates deep-cycle capability and high-current output. One battery I've found has 186 plates and a 75-amp, 12-volt output for 100 minutes.

Steve Hula
4/4/2012 2:02:08 PM

Please tell me how I can contact Mr. David Arthur's?

7/22/2008 12:00:59 AM

Is there a way to contact David Arthur's. From one item I read I assume he no longer lives in Springdale, Ar. Thank You, Al

9/10/2007 4:45:04 PM

With 60,000 of the plans sold I would like to see Mother Earth News have reports on these converters progress. A column in the mag. where they can ask Mr. Arthurs questions. Check out They have web pages with a picture and itemized details of the individuals vehicles, parts used, etc. A blog would be nice so converters could exchange information,advice, or tips. I have a 96' Saturn with 107k miles on it. I am waiting for the engine to kick the bucket so I can start my conversion of it. However, its running great and is great on gas. I may have to find a different car. I think M.E.N. is missin' the boat. I can see electric/hybrid car clubs starting up all over the country and around the world. Good luck to all.

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