Electric Sportscar

Electric Horseless Carriage

The Shop


Lotus Info


"A man must keep a little back shop where he can be himself without reserve. In solitude alone can he know true freedom."
-Michel De Montaigne 1588

Making it a Hybrid

Next step is to add a gas engine and generator to make it a true hybrid. The trick is going to be to control the gas engine so that the generator supplies just the right voltage and current to charge the batteries. Not sure how I'm going to do that.


Well I figured that there was no use trying to reinvent the wheel, so I decided to go with a 24 volt alternator and a small gas engine.

At first, I thought I might take a weed-whacker motor and chain drive a 500W DC motor/generator similar to my main drive motors but that idea just kept getting more and more complicated. Speed reduction, complicated mounting brackets, voltage and current control, and so on....

So I started looking for a 4-stroke motor since I really didn't want all the hassle of mixing gas and oil. Besides, 4-strokes are quieter and don't smoke. I found this great little Honda 25cc motor that looked perfect. I wasn't expecting it to come with a centrifugal clutch though.

Well it was that clutch that gave me the idea of mounting a regular car alternator directly onto the motor. A 24 volt alternator would be even better.

The only 24 volt alternators I could find were great big industrial units. Way too heavy. The solution was to fit a 24 volt regulator to a standard Toyota alternator. I'm not sure yet how well this will work. I may have to get the rotor rewound to handle the higher voltage. I hope not though. The standard alternators are built to supply power at fairly low idle rpm. (600 engine rpm would be about 1200 alternator rpm on a car) The centrifugal clutch on the Honda cuts in at 4000 rpm so the alternator would never spin slower than that.

Many thanks to Joe Falkner of Commercial Alternator and Starter on Oshawa Ontario for all his help and advice with the alternator.

Had to do some minor machining to the alternator casting to take the adapter plate. I used heli-coils in the aluminum for extra strength. I also had to turn down the rotor shaft to take the clutch drum. When I tried to thread the shaft, I got the die a little crooked and the drum wobbled like crazy. So I cut off the crooked part, bored the shaft and ran a tap into it using the lathe as a guide to keep it straight. I cut off the end of a 3/8" grade 8 bolt and locktited it into the bore. That worked much better.

The adapter was machined from a 4-1/8"D x 2" bar of aluminum.

The 45 deg offset in the flanges is for clearance to get a wrench on the the bolts.

Since the alternator is mounted directly onto the motor, there won't be any torque transferred to the mounting bracket. The bracket can be fairly light.

Here are all the pieces ready to assemble.

Ready to mount. The centre of gravity ended up right at the centre of the mounting bracket.

Now to start working on the electrics. I'm not sure how the motor will react to the varying load of the alternator. It may slow the motor down to the point that the clutch slips. I am going to try to fit a speed governor to the motor. I think that will help.

Here is the motor/alternator mounted and ready to go.

All the wiring is done.

I had to rework the dash to add a bicycle spedometer/trip meter and ammeter and voltmeter instrumentation.