Hazards of Owning a Toyota Prius

With all new technologies come hazards, real and perceived.  Will holding a cell phone at the side of your head for hours every day eventually fry your brain?  Will radial keratotomy improve your eyesight or destroy it?  It can be surprising how, when a technology becomes mainstream and is taken for granted, we forget the hazards, even the most real ones.  We happily propel a ton-and-a-half of steel, glass and rubber around the country's roadways at 60 miles per hour, sometimes feet away from similar objects travelling at similar speed in the opposite direction, all the while with ten or more gallons of highly flamable liquid in a thin steel tank under the back seat.  Yet, if someone puts a powerful electrical system in the car, we suddenly get nervous all over again.  In this section, I'd like to talk about the hazards of Prius ownership.

High Voltage Electricity

A domestic electric clothes dryer (in the U.S.A.) operates at 220 volts and 30 amps.  The Prius high voltage system runs at about 273 volts, a little more than the dryer.  Currents can exceed 30 amps, but in the case of electric shock it's the current through you that does the damage and any system that can supply an amp or more is as dangerous as any other.  How much damage you'll suffer from a 273 vold shock depends on your body resistance and how the shock passes through you.  I happen to have experienced a 240 volt shock from one hand to the other, straight across the heart, with little more than temporary discomfort.  But I was stupid.  I grabbed the terminals of my father's arc welder without waiting for him to turn it off.  If you're not stupid, you can operate a clothes dryer without worrying about electric shocks.  Equally, and for the same reason, you can drive a Prius.

There's only one difference.  It's a long time since I heard of domestic appliances crashing into each other in the basement.  But, you hear of automobile accidents all the time.  Suppose someone broke into your house and set about your clothes dryer with a sledge hammer.  You come home and it has wires hanging out.  Do you touch them?  No, of course not.  This is all it means when Toyota warn you not to touch wires hanging out of your car after an accident.  The high voltage wires are wrapped in metal shields to protect them from cuts.  They are colored orange.  Compared to the other harm that can befall you in a car crash, I would say that the danger of electrical shock is insignificant.

Battery Electrolyte Spills

Cars have batteries.  Batteries contain acid.  Acid is dangerous.  A car with powerful batteries must contain a lot of acid and be very dangerous, right?

The electrolyte in Nickel Metal Hydride batteries is potassium hydroxide.  This is not acid, rather it is an alkali, the exact opposite.  However, concentrated alkali can be as caustic and dangerous as acid, so there are warnings about spills.  This should not be of any concern, however, because the location of the battery in the car protects it well and each cell of the battery contains very little electrolyte.  By far the biggest secondary risk in a collision is, in my opinion, the gasoline, as with any normal car.  But Toyota don't want to be sued for alkali burns just because they failed to include a warning.

Driving in "Stealth" Mode

I don't think "stealth" is a Toyota word, I think people in the yahoo discussion groups invented it to mean driving with the gas engine off. The implication is that you can sneak up on people, which is unfortunate because obviously this is not always a good idea.

Also, people talk of a stealth "mode". You can't put the car in this mode, the car makes up its own mind when to run the ICE and when not. You can influence the car by the way you drive, but you should probably consider this "advanced Prius ownership" for now. In fact, the philosophy of "Prius - just drive it" would have you leave it up to the car. Those of us searching for extreme economy and a fuller understanding of the car's workings are the ones talking most about stealth or "EV" (electric vehicle) mode.