Drive it forever
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Q. I am not a mechanic, but I have a few efficiency ideas.
Couldn't they build a car that ran the air conditioning, power steering, and all the other accessories electrically, rather than with belts? The roof, hood, and trunk could use composite solar panels, constantly charging the batteries. These batteries would in turn supply power to heat up water and turn it to steam, which would drive the car.
Then we could put generators on all four wheels, just like the ones that we had on our bikes to run the lights when we were kids. These generators would charge the batteries, and we could stop using fossil fuels.
Wouldn't that be great?
A. It would be great. But your ideas won't work.
First, several cars already on the market use electrical power steering, rather than conventional belt-driven, hydraulically boosted power steering. And the
But those solar cells . . . you've greatly misapprehended the amount of energy needed.
I'll be generous and say there are a couple of hundred watts of power available from sunlight striking the area of the hood, roof, and trunk. I'll be even more generous and say you can collect the full output of those cells for 12 hours each day. That works out to around 1,000 watt-hours per day, if and only if the car is parked or driven in areas where full sunlight is available all day.
In the real world, the available power would be less than half that, because the sun isn't directly overhead all day.
The battery pack in the still-in-the-works Chevy Volt will be 16 kilowatt-hours - though the usable capacity will be about half that, to protect the batteries from being damaged by a state of undercharge. That means that the best-case scenario for your proposed electric car would require it to be parked in the sun for a couple of weeks in order for you to be able to drive it for the Volt's rated electric-only range of 40 miles.
Realistically, it's more likely that those 40 miles would require more than a month's worth of baking in the sun in a parking lot. Longer if you need heat, air conditioning, windshield wipers, headlights, or taillights. This may explain why there are no pure-solar cars on the market.
Q. Recently I used a battery charger-booster to jump-start my car. I had just installed a new battery, and one of the battery terminals had been left with a poor connection, probably because I didn't tighten it enough.
The next day my car would not start, so I attached the battery charger and activated the start-boost feature, which is rated at 30 amps. When I turned the key to start the car, I instantly heard a loud buzzing sound coming from the speaker system. I've never had a problem with this charger before.
A. You've almost certainly blown a diode. How? The voltage regulator controls the current in the rotor windings, which in turn controls the voltage output in the stator. Short the output to ground, and you get lots of current, lots of heat, and a melted stator. If the output is open, though, the current in the stator has no place to go. The voltage rises rapidly, and soon gets high enough to toast one or more of the diodes. The instantaneous surge can reach several hundred volts, and diodes used in alternators are rated for only 50 volts or so.
A decent technician, or even a decent tinkerer, can test and replace the diodes, but it might be easier to simply replace the alternator with a rebuilt one.
Mike Allen is a senior editor for Popular Mechanics magazine. Questions should be sent via e-mail to driveit@nytimes.com.
