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The Mother Earth News September October 1980

MagazineThe Mother Earth News
DateSeptember / October 1980
TitleIsrael’s Solar-Powered Car

In this article, the staff with The Mother Earth News took a trip to Isreal and found a Citicar being powered with solar panels.

Israel’s Solar-Powered Car article with photo courtesy of Professor Arye Braunstein

During MOTHER’s solar tour of Israel earlier this year (see page 90 for details on next year’s tour offerings), on of this publication’s editors took the opportunity to stop by the Engineering Department at Tel Aviv University… to gather some information about a solar-powered automobile being developed there under the direction of Professor Arye Braunstein. Even though the car was partially dismantled at the time of that visit, we felt sure that many of our readers might nonetheless like to learn a few of the details concerning the sun-driven runabout.

Israel’s Solar-Powered Car, The Mother Earth News, September/October 1980, page 120

Its astonishing to discover an American-Made CitiCar in Israel of all places, and as a test for solar powered vehicles. There have been attempts to recharge the CitiCar with solar panels. My own CitiCar came with a pamphlet showing solar panels on top of a CitiCar.

Professor Arie Braunstein was focused on quite a few projects, and papers regarding lighting.

The basic vehicle is-as some of you may realize from the accompanying photo – a metal-framed, polyvinyl-bodied Citicar that weighs in (complete with batteries and solar panels) at 1,320 pounds. It runs on a two-step (24/48-volt) DC system, which is controlled by a series of microswitches and relays: At speeds up to 10 MPH, current is drawn-through resistance-from two banks of four-in-series six-volt batteries. After starting, the resistance is dropped and the car operates on 24 volts normally, and at cruising speeds (up to 40 MPH) the series-wound motor functions at 48 volts… with all eight batteries “in line”. Although initial current draws can reach 500 amps, the average pull at cruising is around 100 amperes.

Israel’s Solar-Powered Car, The Mother Earth News, September/October 1980, page 120

This is the general description of how the CitiCar works. However, of significant note here is that they specify the amperage, with 100 at cruising speeds, and 500 as the motor strains to adjust to a new load or speed. The first step seem often to be in question as to what speed it operates at, and what it reduces the voltage to.

The two solar panels on the auto’s hood and roof (which have a combined peak power of 400 watts with a total of 432 cells) charge the batteries at 48 volts and provide about one-third of the energy required for daily driving… up to a maximum range of 50 miles. The remaining electric “fuel” is stored at night, using a built-in home charging unit.

Israel’s Solar-Powered Car, The Mother Earth News, September/October 1980, page 120
Five 12 volt, 4 amp battery chargers

I’ve noticed that when I have five individual battery chargers on each of my 12 volt batteries, they take around a combined 350 watts at most, with an eight hour charge. A 400 watt panel would surely be enough to power for an on-board charger while the sun is up.

What is quite remarkable – I believe he’s trying to to drive the car directly from the solar panels. You would need somewhere around 4,800 watts if you were already coasting at top speed (100 amps, 48 volts)

Dr. Braunstein is the first to admit that the solar Citicar is by no means perfect but his researchers are steadily improving the vehicle and have several specific goals in mind. By using electronic controls and commutation circuits, power regeneration, permanent magnet or AC motors, and stationary – rather than “on vehicle” – solar cell arrays (the latter coupled with exchangeable sets of efficient batteries), the professor and his staff hope to increase the percentage of solar-provided energy to as high as 90%… double the effective range of the vehicle… and add another 10 MPH to its top speed. And – since they’re located in one of the sunniest regions in the world – it seems likely that they’ll be able to accomplish their objectives!

Israel’s Solar-Powered Car, The Mother Earth News, September/October 1980, page 120

It sounds like the professor was focusing on regenerative breaks that AC motors and permanent magnets offer. With stationary panels is something I’m looking into myself with a DIY Personal Solar Charging Station using a portable EVSE using an inverter, battery bank, solar charge controller, and a few panels.

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