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Following the advice of my mechanic I recently refused to...

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Dear Tom and Ray:



Following the advice of my mechanic, I recently refused to give someone a jump-start for fear of racking up another $250 bill for a new alternator. Was I a bad Samaritan, or was I justified in leaving this guy stranded? -- John

RAY: Well, many manufacturers now recommend against giving or receiving a jump-start. And at the garage, when possible, we "trickle charge" batteries -- charge them slowly over many hours -- instead of jumping them with a large surge of current.

TOM: I guess the theory is that when you give a jump-start, you use your charging system to charge two batteries (yours and the jump-startee's), and that can place too great a demand on your alternator and can overheat it.

RAY: And the reason they recommend against receiving a jump-start is that it's possible to fry the delicate electronics in today's cars with a voltage surge. And if you think ruining an alternator is bad, you should try cooking a thousand-dollar computer!

TOM: In reality, however, this stuff is extremely rare. I can count on one hand the number of times we've seen problems due to jump-starts in the garage in the past 25 years. And most of those occurred when some knucklehead mixed up the positive and negative cables. So it's a risk, but, in my experience, it's a very low risk.

RAY: And personally, I don't let it interfere with my Samaritan-ness. If I see someone who needs help, and I can help them, I don't think about my alternator. And I hope other people would do the same for me.

TOM: What about me? Would you stop to help me if my battery was dead?

RAY: Sorry, I'd love to, but I just had a new alternator put in.
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