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MOTHER:

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

Dave Arthurs:

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.

MOTHER:

But does a conventional engine still supply the batteries with power?

DA:

Absolutely. That's a must if you want to travel distances of over 25 miles. The small combustion engine must operate at a constant speed if a long-range drive is in the works, supplying the batteries with power. I installed three 12-volt, heavy-duty automobile batteries—in series—"fed" by a 10-amp generator to do that job. The small engine then powers the generator. But I decided I wanted a bit more power in the new pickup, so I decided to forgo another five-hp gasoline engine in favor of a nine-hp diesel. That's equivalent to about a 20-hp gasoline engine. It turned out to be a perfect arrangement. It has tremendous torque, will bear very heavy loads without stalling, and is incredibly reliable.

MOTHER:

Can the batteries be charged at home if you want to just use them for a short trip?

DA:

Sure. Either a 36-volt charger can be used to charge all three batteries at once or a 12-volt model (which is much less expensive) can be used to charge each battery individually. Either one can be plugged into a standard home outlet. The electric rate here in Arkansas is 74 per kilowatt-hour. At that rate the cost is less than a penny per mile to operate the hybrid in the electric mode. But the range is limited by the number and type of batteries that you use. If you want to be able to drive for longer distances on the electric drive alone, the battery pack must be enlarged accordingly.

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