Question: Although it's too late for me, since I've already done irreparable damage, just what is the correct way to use jumper cables to start one's car? I've heard every possible variation on how to connect and start one's dead car with the tangled mass of black and red cables that live in every trunk. Thanks. - Shelley
Tom: Is THAT what that tangled mass of cables in the trunk is for? I thought that was the speaker wire for my eight-track player.
Ray: You have three objectives when you're jump-starting a car, Shelley. The primary objective is to not cause an explosion. Objective No. 2 is to not damage either car's electrical system. And objective No. 3 is to get the "dead" car started.
Tom: The way to avoid damaging the electrical systems is to clearly identify the terminals of both batteries. Make sure you know which terminal is positive and which is negative before you start. Unfortunately, the markings aren't always as clear as they should be, so you may have to scrape off some dirt or use a flashlight to get a clear look at the marks.
Ray: Once you've identified all of the terminals, you can proceed to the next step: avoiding an explosion. When batteries explode, it's because a spark has been created in the vicinity of the battery. So the key is to avoid creating a spark anywhere near the battery.
Tom: Sparks can only fly when you make the very last connection of the jumper cables and complete the circuit; in other words, when you have three cables' ends hooked up and you're attaching the fourth. That's why you want to always make that last attachment away from the battery, and here's how you do it.
Ray: So here's the procedure. First, make sure the "live" car's engine is turned off. We find this cuts down on necktie-in-the-fan-belt syndrome. Although you could start with either car, we're going to suggest you start by taking one end of the red (positive) cable and clamping it securely onto the positive terminal of the "live" car's battery.
Tom: Next, take the other end of that red cable and clamp it to the positive terminal of the "dead" battery.
Ray: While you're over at the "dead" car, take an end of the black (negative) cable and attach it to the negative terminal of the "dead" battery.
Tom: And then, to avoid an explosion, you attach the other end of the black cable to some large, metal part of the engine block on the "live" car - not to the negative terminal of the "live" battery. The negative terminal of the battery is simply a ground terminal. And by using another, more remote piece of metal to ground the circuit, you can make sure that any sparks that do fly are kept far away from the battery.
Ray: OK, now you've avoided both damage to the electrical systems and a major explosion. Good! You're two-thirds of the way there. Now you're ready to start the car.
Tom: Make sure all accessories (lights, air conditioner, etc.) are turned off in both cars. Then start the car with the "live" battery and keep it revved at medium speed (about 2,500 rpm) for a few minutes. The alternator of the good car will then be effectively "charging up" the "dead" battery. Then try starting the "dead" car. If it doesn't start, rev the "live" car for five or 10 minutes more, and try again.
Ray: If it doesn't start after that, give up and call for help, because something else is probably wrong. Continuing to mess around with it at this point is only going to increase the chances of failing to achieve Objective No.1 (see above).
Tom: Once the car with the dead battery has started, you remove the cables in the exact opposite order that you put them on, again taking care not to create sparks or get your ponytail stuck in the fan.
Ray: Then you throw them back into the trunk so they can resume their historic role as a mass of tangled black and red cables. But clip this article and tape it to the cables so you'll know what to do next time, Shelley.
Question: Last year I forgot to drain out my gas in several lawn-mower-type motors, and this spring, they all started perfectly. I know you guys have recommended a gasoline stabilizer for seasonal storage, but how come my motors started right up? I used unleaded gas without alcohol. Without the lead, can gas be stored without varnishing? - Elmer
Ray: I can tell you're a scientist, Elmer. You've experienced an interesting phenomenon - your lawn mower started perfectly after a winter of storage - and now you're testing a promising theory: Can unleaded gasoline be stored without producing varnish?
Tom: And like a scientist, you're about to utter the well-worn words "Dang! Back to the ol' drawing board." The phenomenon you experienced, Elmer, was luck.
Ray: Unleaded gas still tends to varnish. And without a gasoline stabilizer, a lot of engines stored with sitting gasoline over a period of many months won't start. And worse, their carburetors may need to be removed and cleaned if you ever want to get them started again.
Tom: This is a classic application of our famous Great Unyielding Truth: It's the stingy person who spends the most. You try to save a few bucks on a can of gasoline stabilizer, and you end up having to rebuild the carburetor later on.
Ray: So you can press your luck again next year, Elmer, and you may get away with it. Or you can play it safe and take our advice: Bite the bullet, buy a can of stabilizer and ensure yourself a place next year among the great, unvarnished masses.
Question: Could someone tell me why a "space-saver spare" cannot be fixed? I went to five gas stations and a tire store, and got the same answer: "Because it's a temporary tire." So what? It's still made of rubber like other tires, isn't it? Why won't anybody fix this? - Jan
Tom: For the same reason you don't bother patching a hole in a Dixie Cup, Jan. It's engineered for limited use (i.e., it's cheap junk), and the rubber isn't thick enough to hold a plug reliably.
Ray: These so-called space-saver spares are designed for emergency use only. They're just good enough to get you off the highway, or off the abandoned side road, and to a gas station where you can get your regular tire fixed or buy a new one. In fact, most of them warn you not to exceed 50 mph and 50 miles of driving.
Tom: Why do they use such a flimsy tire? Well, if the rubber had the same thickness and durability as a regular tire, it wouldn't, what? Save any space!
Ray: It's a compromise, Jan. Because tires are so much better than they used to be, people get fewer flats. And because most people drive in the general vicinity of civilization, 50 miles of driving is usually enough to get you to help.
Tom: So on the odd chance that you have to use your minispare and you wear it out, you buy a new one. And for the average person, who gets a flat once every five to eight years nowadays, this system works just fine.
Ray: If it bothers you, you can always go out and buy yourself a full-size spare. It'll cost more, it'll add weight to the car (which cuts down your gas mileage), and it'll take up more space. But it's certainly a viable option.
Tom: And if you don't want to give up all that trunk space for a full-size spare, heck, you can do what my brother does and just throw it in the back seat!