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Jumper cables started smoking, meleted entire insulation, WHY?

This question is for my wife and coworker. While traveling on a company car their Chevrolet Trailblazer would not start. They hooked up jumper cables to a good car…positive to positive and negative to negative. They swear they had it hooked up right. Well the cables got so hot, smoke started pouring from cables and melted them beyond any future use. Has anyone ever had this happen or know why? Thanks in advance.

Cheap jumper cables are 10ga wire which is not adequate to jump start a car. Cables that light are only useful to connect a dead batter to the battery on a running vehicle and allowing the dead battery to charge for whatever time is necessary to charge it. If the starter is operated before the battery is fully charged the cheap wires will get very hot. Real jumper cables are 0 gauge. Shops use 00 gauge.

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Cheap jumper cables would be my first guess. A lot of those cables you get at Walmart or in those little emergency kits you’re supposed to give teenagers at Christmas are garbage, and simply can’t handle the output of a good battery.

A good jumper cable should use a large-gauge cable. They should look like they’re for energizing Frankenstein. Mine are 0 gauge. I usually recommend a minimum of 6-gauge wire for very light duty stuff.

The crazy part is that the good ones don’t even cost much more than the junk ones. You can get a good set of 2-gauge cables for 35 bucks.

This is a good example of putting yourself at risk on a company vehicle. A wrecker service would have used a jumper box for $25.00 to $50.00 and if something went wrong at least the company employee can’t be held responsible for an expensive repair.

Don’t most company vehicles have road side service included in the lease agreement ?


Not only the gauge, but also the material. 4 gauge COPPER are the best. I don’t use mine much (mainly on other peoples cars). But the set I have are easily 30 years old an never failed me yet.

It’s easier to hook up cables incorrectly than you might think, so I wouldn’t rule that out, especially if someone connected a red cable to the battery’s negative terminal and a black cable to the battery’s positive terminal. This is why I always check the battery itself (looking for the plus and minus symbols), and don’t rely on the cable colors.

There is a good chance the jumper cables were hooked up backwards. Some modern cars have safety equipment that will keep the battery from exploding in such circumstances. When the battery doesn’t blow up, it fries the cables. Electricity has a way of behaving one way on one car, but differently on another.

The thing that makes it difficult to know is that, when you hook up the jumper cables backwards, you get a large spark, but when I hook them up correctly, I look for a small spark to show me I’m making a connection.

Jump starting is so dangerous that I don’t do it anymore. I bought a jumper box I use instead. It shuts itself down if you connect it incorrectly.

I’ve used cheap jumper cables many times, and they don’t melt from proper use. They just take forever to charge the dead battery before you have enough juice to start your car.

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If you are referring to the aluminum cables I have seen them but have never been brave enough to try them.

Yea…me either. I’ll stick with Copper.

Under what circumstances did they get hot? For example, did they get hot immediately after connection? Or while cranking the dead truck? If the latter, how long were they trying to start the dead truck before the problem was noticed? Were they even able to crank the dead truck? What was the eventual conclusion after the cables melted down? Did a tow truck come and get it started?

Answers to these may help to isolate incorrect connections from undersized jumper cables being the root cause.

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It may be that the jumped car’s battery was so depleted the cables couldn’t handle the current and burned up. Or it could be the jumped battery was internally shorted causing the same thing. Either way, new time be aware of the cables disconnect immediately if they get get very warm.


00 Gage Cu is equivalent to 0000 gage Al
0 Gage Cu is equivalent to 000 gage Al
2 Gage Cu is equivalent to 0 gage Al
4 Gage Cu is equivalent to 2 gage Al

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thanks man! the spark was a good give away, as I was jumping a Diesel Jetta tdi from a tiguan I was searching the cable issue, (heating up and what not). Thought id switch the cables around, wondering if there is some manufactures discrepancy? I work with engines all the time and I swear to my mother the cables we’re hooked up red + to red + and blk - to bulk- on both vehicles, After switching the cables presto, the jetta fired up , some minor radio issues (burnt fuse, which i have been trying to track the cause of, ) all because the symbols are marked wrong… seems silly… thanks none the less!

No its not improper placemnt of the cables.Its cheap thin cables that cause the overlaid making them smoke and melt. Like someone mentioned ,if you connect the cables improperly ,you’ll get a large spark . Therefore you wouldn’t continue to charge the battery ,you’d quikly remove the csbles,or I had hope you would. Because after not removing them you would have damaged something in the car lewvig it undeniable unchangeable until issue was fixed. So they hooked the cables up correctly.