When a jumpstart goes wrong? Safety Question

Neighbor tried jumping my wife’s ‘06 Nissan Altima, we left it for 10 minutes and came back and the cables had melted through the headlight of both cars and some of the bumper. I wasn’t there but thankfully they stopped their car and were able to disconnect the cables without incident. We noticed after there had been mice living in around her engine from the mouse poop, minimum the last two weeks. What causes jumper cables to do this? Something a rodent may have chewed? Definitely an issue with my wife’s car. Our poor neighbors have a newish midsized suv. My wife has also had constant issues starting her car, even with a new battery I got a year or two ago. Anyone seen this before?

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u/MarsRocks97 Dec 31 '23

Tight isn’t the issue. Each clamp MUST be clamped to the correct polarity. Mismatching will cause the cable to overheat and quite likely also ruin the weaker battery possible both batteries.

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u/jhwalk09 Dec 31 '23

That’s what I meant he insists he clamped em to the right ones, black to black red to red

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u/Joiner2008 Dec 31 '23

As a guy who went to tech school for diesel and auto, who does his own repairs, who has done half a dozen fuel pumps, a timing chain, a few head gaskets, etc. I once hooked my jumper cables up to my Jetta wrong. We all fuck up at some point. It has opposite sided terminals on the battery and the positive is brown. The jumper cable sheathing started to melt but I was there and saw it happening. This IS the reason this happened to your car, your neighbor doesn't want to admit he fucked up something this simple.

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u/Innit2winnit23 Dec 31 '23

And it's not out of reach to overlook a battery sitting the opposite way in one car than in the other then while red is on the left in one and the right in the other and you never gave I a second look before putting red on the left the 2nd time and now your headlight is wearing a bit of an eyepatch

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u/Joiner2008 Dec 31 '23

Yeah. I'm used to GM where red is on the right. The Jetta battery is parallel instead of perpendicular, the positive is on the opposite side, and this is the color of the cable:

https://www.ebay.com/itm/276048899771

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u/Innit2winnit23 Jan 01 '24

Yup that'll fuck you up if you're not paying attention! Complacency kills!