Melting battery cables

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Yesterday, I dropped my daughter off at her friend's house while I ran some errands. I was supposed to pick her up at 3 to get her to the airport by 3:30 pm for her flight back to Seattle. I went to the library and then took a walk by the greenbelt. Had a nice walk and got back to the car. Tried to start it up and nothing. I mean nothing. The car had started flawlessly up until that point so it didn't seem like a traditional case of the battery slowly dying (and it's not that old).

Fortunately, a guy drove up to rollerblade the greenbelt, had jumper cables, gave me a jump (the car started right up) and off I went. I left the motor running while I picked up my daughter and when I dropped her off at the airport (plenty of time, she made her flight and is safely back at uni).

I got home, pulled in the garage and turned off the engine. A few seconds later, I tried to turn it on and nothing. Absolutely nothing.

I got my son to drive me to work today and I walked home. I'd made arrangements to drop my car off at the local garage after hours. My wife came home and I got out our jumper cables. I hooked them up to my wife's battery but hadn't gotten to hooking them up to mine yet. I put on my shoes, looked up and the cable was smoking. The plastic handles were melting. I quickly grabbed a rag and unhooked the cable from the battery. The entire length of the cable was hot.

Naturally, I didn't get my car started and down to the garage. I'll have to waste time arranging for a tow tomorrow and hope the guy at the garage can give me a ride to work.

Has anyone had anything like this happen to them? What would make the cable melt?

 

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This is horrendous! I have heard that a car battery can produce up to around 300A of current to start a car, so if it there was a short-circuit , with this level of current, something could surely melt.

If there is no noise whatsoever when trying to start your car, it could be a bad connection somewhere, such as a bad earth connection. Sometimes wiggling the wires around can show up an intermittent connection. It could also just be a bad battery.

I have had car-starting troubles of my own, and been to the garage now three times, and each time they've not found the problem (2 new alternators, 1 new battery - now a 2nd new battery (fortunately all under warranty)). My battery runs right down after about three weeks. I suspect a short circuit, and so what I do is disconnect one of the battery leads every time I leave the car. Cumbersome, but at least it will (hopefully) stop the battery running down for now.

 

The thing is, it wasn't the bad battery in my car that melted the cables but the perfectly fine battery in my wife's van that did the deed.

 

Trip joe said, could the other ends of the cable been touching each other when you hooked the one end to your wife car. He said if they were hooked togather, laying on top of each other or touching while hanging there, that it would do that in a heart beat. Do you know if they were touching by chance?

 

It sounds as if you have a dead short between positive and negative somewhere. One very real possibility is inside your battery, if I'm reading you right that it was the jumper cable that was melting.

Is it a maintenance free battery or one that requires you to put water into it occasionally? If the second pull the caps off and I'll bet you'll find the battery is empty.

If you have an kind of volt/ohm meter take the cables off the battery, check for any voltage across the two poles, and if you have 0 volts in the battery check the resistance across the battery. The resistance should be very high, in the meg ohm range. If it's very low you know your battery shorted out internally.

 

The melting cables weren't caused by my misbehaving battery and I didn't *think* that the ends of the cable on the garage floor were touching (I didn't want them to spark), but who knows? It seems the most likely cause at this stage of the game. I'm calling the road-side service and either getting a jump so I can drive to the garage this a.m. or get the car towed there.

I know this sounds odd for someone who works in technology and especially for someone who's written a hands-on A+ book, but I'm not very mechanical. I just want the freaking car to *work*. I know...I'm very "end user" that way.

EDIT: Oh...yeah Freddy. I popped open the "lids" or whatever they're called and noticed that one cell especially was low, so I used a turkey baster to add water. I don't know if that should cause enough of a reaction to get a charge out of the battery, but I suspect not. Anyway, The car was due for a checkup and oil change anyway (overdue, actually), so maybe this is G-d's way to tellling me to get the thing in for that sort of thing.

 

Any chance of some pictures? Maybe if we saw the area/damage then we would have a better idea of how it happened. Still on the other hand I have to say you were very lucky Trip it could of been a lot worse. Thank god you and your family are OK!

 

When adding water to a battery cell it should be *distilled* water. Bottles of this are available (in the UK at least) at most reasonable garages,

Home tap water is just too full of salts and other chemicals, and will shorten a battery's life.

Excessive current is obviously the reason for the cable to get hot, and, of course, the clip at the end of the cable will get extra hot because the clip isn't the best connection in the world. Unless they are rather special cables, 'jumper cables' are only intended for use over a very short period.

So why the excess current? First thing to check is the polarity. Some years back in the UK vehicles were a mix of +ve and -ve polarity, although these days this is less so. This taught me to check the polarity before connecting jumpers!

As has been said - if the battery has an internal short then this would cause the excess current. This would also explain the other symptoms you had - possibly a connection is dead somewhere as well, so you were driving on the alternator with no battery effectively in circuit.

Harry.

 

Remember also that a short circuit could occur not just with the red and black jumpers cables touching together, but (assuming a negative earth system, ie. the car bodywork connected to the battery -ve terminal) the positive (red) cable touching any metallic (and henced earthed) part of the car.

This would give it a return path back through the -ve terminal of the battery, just as if the red and black cables had touched together.

Likewise, if it is a positive earth system, a short circuit would be caused by the negative (black) cable touching any metallic part of the car bodywork, as this produces a return path back through the positive battery terminal.

 

Yep as said if one part of cable is touch metal or almost touch it and the other ends connected this could cause the short.

Also do not use normal water it is supposed to be distilled normal water can carode the insides of the battery.

 

Yeah...I probably let the metal ends touch on the cable which melted it. My battery was just plain gone and I had to have it replaced. Got to work late right in the middle of the scrum meeting so I was very noticable.

 

Trip,

On your wife's car, if it was the jumper cable that was heated, chances are that either the handle connected to the positive side had laid over against a metal ground and shorted, or the other end of the cable had come in contact with either the other cable or some metal part of the car and shorted that way.

Be sure to have the mechanic to check the batteries on both cars. A short of that magnitude can warp the plates in the battery in a heartbeat. On your car, if the battery turns out OK, check the connections both between the positive battery connection and solenoid or starter, and also the ones between the negative connection and the ground. A loose connection at any of these points can cause the battery to lose charge or prevent full voltage for starting.

Rover,

Your problem can be narrowed down rather quickly with the use of a small test light or an old tail light or marker light.

Disconnect the ground cable from your battery and connect the test light between the battery and the cable. Chances are the light will be lit, indicating a voltage drain from the battery or a short circuit. Depending on whether the vehicle uses fuses or circuit breakers, pull them out and then replace them one at a time. When the light goes out, you've found the faulty circuit. Most of these are marked to give an indication of which componants are connected to that circuit. (ie. pwr. windows, tail lights, dome light, and so on).

Don't know how much I can help from here, but feel free to post back.

Bill

 

Thanks, BB. If you'll look just above your last post and see my missive, you'll see that my battery was just bad and I had it replaced.

 

Let me get this straight James.. you allowed the end of the jump leads to touch eachother and you are suprised the cables melted?

This would have caused a huge amount of current to be drawn from your wifes car. It is the current capability of car batteries that do the work of turning over a car engine. imagine how much current that would take and the assocated circuitry (starter motor etc) is not a dead short. Lower the resistance ie short the ends of the leads and the current will go up proportionally. To a point that the cables will get so hot that the PVC will melt.

I (current) = V (volts) / R (resistance)

you do the math..

V = 12

R = near zero (there is not much resistance in jumper leads).

You are talking hundreds of amps.

 

the maths doesnt add up its the right formula it just doesnt make sence

because 12/0 (V/R) = 0 as you canot devide by zero.
will the currnet be 12ohm thats a tad small.


unlessim being a retard.

 

Hehe, well the resistance will never be zero.. so try .05

 

I didn't intend to "allow" the two hot ends of the jumper cable to touch and in fact thought I'd put them down separated. However, since the most likely cause of the cables basically melting is the two hot ends touching, I can only believe that the cable shifted as I put that end down and turned away and they did indeed touch. Yes, I'll accept the "Moron-of-the-Month" award for this one.

Fortunately, all's well that ends well in the inkwell. My wife's rig was no worse for wear, I got a new battery (gosh, they're expensive these days), and my car starts up fine again. Good think too, since we're expecting more snow.

 

Could have been a lot worse. I saw a battery explode once in the face of a mechanic. He was lucky, wore glasses. Did they happen to check your charging system while it was at the shop?

 

Yes. Dave (my mechanic) said the charging system was fine. Thanks for asking.

 

Near zero isn't zero. Thus, you're not dividing by zero. 12 divided by a super-small number equals a super-big number.