Find out why you might want to take a pass on one, new type of jumper cable.

Dear Car Talk

Dear Car Talk | Jul 01, 2007

Dear Tom and Ray:

My wife, who must be obeyed, has brought home a device to replace her car's regular emergency-jumper cables (which are still in pristine condition). The device she purchased connects from her car's cigarette lighter to the cigarette lighter of a good Samaritan's car. Are these things safe? -- Jer

TOM: Sure, they're safe, Jer -- they're safer than jumper cables. They're just inefficient.

RAY: Right. It's like drinking a gallon of water through one of those really thin stirring straws that bartenders use.

TOM: In order to jump-start your car, you have to get a bunch (note: technical term) of electricity from one battery to the other. Usually, you do that with jumper cables, which are thick copper wires that can move a lot of electrons.

RAY: If you make the wire thinner by using really cheap jumper cables, or by using one of these lighter-to-lighter devices, the "pipe" is thinner, and fewer electrons can travel through the wire at one time. That means it takes longer to transfer the electricity. And in the case of the lighter-to-lighter connections, which use, like, speaker wire, it takes a lot longer.

TOM: So, depending on how dead her battery is, your wife could be sitting there waiting for an hour or two before she can start her car -- assuming the good Samaritan thinks she's cute and doesn't mind chatting her up for that long.

RAY: If your main concern is safety, however, and time is less of an issue, then they're fine, Jer, and you must obey.

TOM: On the other hand, you might consider getting her a jump pack. A jump pack is basically a plastic-encased auxiliary car battery with its own built-in jumper cables. You plug it in at home to charge it up once every six months or so, and then toss it in your trunk.

RAY: It's not quite as easy to use as the lighter-to-lighter cables, because you still have to attach the clamps to your car battery, but -- on the plus side for safety -- you never need to flag down a stranger to jump-start your car.

TOM: Some jump packs also have emergency lights, AC power adapters and even air compressors built in to fill a flat tire. You can get a basic one for $50 or less now at any automotive department or parts store.
RAY: They're particularly good for people who have cars that frequently break down. My brother owns two of them!

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