[shorod]

The theory is sound, but in practice it shouldn't be as big an issue as suggested above. A working battery (even one that's discharged) is essentially a large capacitor. One popular use for capacitors is for filtering noise. The analogy to a computer power supply is accurate, except what typically happens there is electrolytic capacitors go high in Equivalent Series Resistance (ESR) due to the temperatures they are subjected to. As the ESR increases, so does their inability to filter noise. That noise passes "over" the capacitors instead of through them to ground and effects the circuits. Unless a car battery goes open circuit the ability to filter noise and spikes should not be a problem. Have you ever looked at how noisey the rectified output directly from an alternator is? It is much worse than what you would expect from a set of jumper cables, but when in a charging system the battery filters off the rectified noise and causes a smooth DC output.

Probably of biggest concern with jumper cables would be someone connecting them with reverse polarity (another feature that the "smart" cables Pat advertised have) or a spark when connecting them causing an explosion from battery vapors.

With all that being said, I still recommend having a portable jump start pack and keeping it maintained by charging it every 1-3 months since they use Sealed Lead Acid (SLA) batteries. You don't need to rely on someone else being around or willing to jump start your car, they often have some form or reverse polarity protection along with an on-off switch to prevent a spark when connecting to the battery.

I used to really look forward to Pat Goss' segments on Motorweek. Over the past several years though they have seemed to get more commercial with less focus on his technical experience. I'm not sure if he still contributes in the trade magazine Motor or not.

-Rod