Q Dear Tom and Ray:
At a safety class, the instructor told us that we could be electrocuted while jump-starting a car if we touched the battery terminals. I found this difficult to believe, especially since I had touched both battery terminals at the same time many times before. I bet the instructor $1,000 that I could walk out to the parking lot, touch the terminals on a car battery and live to take his cash. He declined dismissively (as if he was certain to be saving my life). Then a co-worker, who happens to be a nuclear physicist, sided with the instructor, insisting that he had read accounts of people being electrocuted by a car battery. But then again, he thought car batteries were 24 volts. I know that car batteries can be dangerous because of the heat associated with a high-current short circuit and a chemical explosion, but do we really need to worry about a life-threatening shock from them?
A TOM: My brother's always telling me, "Put one finger here and one finger there, and let me know if you feel anything." So that's what you were up to!
RAY: Based on my years of observation and, obviously, failure, I don't believe you can electrocute yourself by touching both terminals of a 12-volt car battery. Twelve volts just isn't enough electrical pressure to overcome the resistance of the human body. So, in my opinion, the instructor and the physicist are both wrong.
TOM: However -- and this is a big however -- batteries are dangerous for other reasons. If you connect the two terminals together with a metal object, like a wrench, you'll short out the battery, melt the wrench and probably cause sparks to fly. Then you'll basically re-create the Hindenburg disaster in your driveway (translation for younger readers: Ka-boom!).
RAY: Plus, there are lots of other things under the hood that can hurt you. Power from the battery travels to the coil, where it is boosted to 50,000 volts or more and then sent to the spark plugs. And 50,000 volts is enough to give you a zap you won't soon forget.
TOM: So while batteries (and things under the hood in general) need to be respected because of the power they transmit, we don't think that simply touching the battery terminals is enough to electrocute you. But don't try it at home. Remember, we're wrong a lot.
Dear Tom and Ray:
I desperately need your help. My dear husband of 40 years has given me the privilege of choosing a brand-new car. Everything was going so well, until it came to my choice of color. I chose an Accord EX in black with a gray leather interior. My husband flipped and said that the leather is too hot and the color is far too hot for our southwestern climate. Has anyone ever done a study of light vs. dark colors and heat? I agree that the black might be a smidgen hotter, but I think the leather will be just as cool. My husband also thinks I will look like a drug dealer, but with a license plate that reads "MOM 11," I don't think that will be a problem.
RAY: There have been studies on car colors, and here's what they've found. Black cars do get hotter than light-colored cars because the darker colors absorb heat rather than reflect it. So you can expect a black Accord to be a little hotter inside than a white Accord.
TOM: And while we don't know of any studies on this per se, in our experience leather seats do get a lot hotter than cloth seats when exposed to the sun. In fact, on hot summer days, if you're wearing shorts, you might hear a brief sizzle when you sit down. That would be the backs of your thighs browning.
Got a question about cars? Write to Click & Clack in care of The Post or e-mail them through the Car Talk section of the Cars.com Web site.
(c)2002 by Tom and Ray Magliozzi
and Doug Berman