jumper cables getting hot and melting

[gary_runyon]

what happenes when you jump a car and the cables start melting?
i jumped my mothers car and this happened anyone know if its a wiring problem.... it was a 1995 eagle vision..

[Chikan]

Sounds like the positive cable grounded out somehow...

[tonyz2897]

Two possibilities. Either they were hooked up incorrectly or they're cheap cables. If you got her car started, then they were obviously hooked up correctly. A lot of your low $ cables look good (really thick wire) but if you have ever seen the diameter of the conductor inside the wire, it's actually pretty small where a good set of cables will be quite a bit heavier. The smaller wire can't handle the current necessary to start a car with a totally dead battery and will get screamin' hot in the process and melt the insulation. The solution to this is to either buy a better set of cables or leave them hooked up for awhile with your engine running to charge the battery in the other car before you try to start it.

Good cables: With the "donor" car running, connect the cables +to+ and -to- then simply start the car with the dead battery.
Cheap cables: With the "donor" car running, connect the cables +to+ and -to- then leave it alone for 10-15 minutes to let the dead battery build up a charge. After that, start the car with the dead battery.
HTH,
Tony

[redrocket91rt]

der. bad connections

[nemesismachine]

youre never supposed to connect battery to battery. you can blow em up that way. "Jumper": + and - on the battery, "receiver": + and engine block.

[holley]

I've connected battery to battery hundreds of times on lots of different vehicles (6v to 24v) and never had any problems - remember that the engine block should be directly connected to the battery negative anyway!

The clamps will often get hot, even on expensive cables, due to contact resistance - but the cheap ones will toast under normal conditions (shouldn't really melt though!).

[mo' parts]

battery to battery can burn up an alternator. hook them up + to+ and - to - on the running engine, and hook the + to + on the car being jumped, and the - should go to the frame or block of the car being jumped.
yes, cheap cables can melt/smoke from the amperage draw, even when hooked up correctly.
highly unlikely thats its a wiring prob., unless your talking about the jumper cable wiring:)

[92lebaronGTC]

I hooked up some backwards once, had to buy new cables after that.

[D-Cal]

Connecting a good battery directly to a battery with an internal short would be very bad. Connecting the ground through the block adds some resistance to the circuit, which keeps the current down in that case.

[puppet]

... and it helps prevent the gas that is present between the poles that can possibly ignite with a spark.

[minimopar]

Actually, the whole idea is this:

The donor car gets hooked to both battery terminals, so that it doesn't have to power the dead car through any of its harnesses. The dead car gets the + on the + batt terminal and the final connection is on the dead car's chassis or cylinder head. The reason for this is that the final connection always sparks and this way the sparks happen away from the battery where there might be hydrogen gas escaping from the battery vents. Also, the starter is grounded via the trans/block/head to the ground lug on the front of the head. If you ground the jumper right there, you are reducing the voltage drop to your starter as much as possible.

Also, alternators on modern cars have had the extra capacity designed out of them. That is why they generally take a beating when they are forced to recharge a completely dead battery. They also don't like to drive a starter on another car for that same reason. Lastly, when the dead car's starter is cranking, the donors alternator is going full-field, giving all it has. When the donor releases the key and the starter disengages, the sudden loss of the huge load and addition of the dead cars alternator output gives the donor car a huge voltage spike before the regulator can pull the field current down again. Electronics don't like that.

[Gumpus]

All my batteries are dual terminal. I have the car hooked up to the one set of terminals, and use the extra ones for doing jumpstarts. Hooking battery to battery directly has worked for me hundreds of times, and I have never fried a computer this way. I HAVE fried a computer by hooking cables up to the same terminals that the car electronics run off of though... I think hooking directly to the battery kinda buffers the voltage to help protect your computer. Another thing I have learned is never hook up the cables with the ignition turned on at the dead car, this also tends to fry computers.

Only time I ever melted anything was trying to jump in the dark without a flashlight and getting them backwards - it melted the terminals on the battery though, not the jumper cables.