jumper cables caught on fire

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BirdClemRV

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Dec 21, 2009
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attempted to start rv - chevy wrkhorse - engine turned slowly but no start.  used my Ford Escape 6 cyl battery to jump start engine battery.  With car engine off. connected cables to + & - on car battery.  Next, connected + clamp to + on rv battery and the neg clamp to brace in engine compartment --- bit of a spark when I clamped the neg to brace.  went to car to start engine. saw cable near rv smoking.  got out of car ASAP and by then the cables were on fire near Ford's battery.  Frantically grabbed cables and burned hands badly but did manage to disconnect all four clamps.  Within two minutes, hands still aching, I went to rv to start it and the engine turned over.  (dah)    What would have caused the cables to smolder and catch on fire?    Very puzzled -- in that rv starts and so does the car engine.  :-\
 
hmmmmm....i would say that you melted some corrosion on the mh terminals and that gave you enough power to start it........is the escape a reverse polarity set up..??  maybe it will say in the owners manual.......

my thoughts???///.....for what they are worth........i hope your hands are healing.........
 
did not check owner's manual to see if battery is set up reverse polarity.  thank you for advice.  hands are healing.  dave
 
Either that or cables too small to handle the current, some of these jumper cables use very small wire, plenty of insulation and not much wire.
 
tvman44 said:
Either that or cables too small to handle the current, some of these jumper cables use very small wire, plenty of insulation and not much wire.
Click to expand...

I thought that too but it shouldn't have happened until he tried to crank the coach and began drawing big current.  :eek:

Rick
 
The only thing that could have caused that is extremely high current.  Too much current without the starter running is most unlikely, unless the jumper cables were connected wrong.
 
Both those vehicles have a negative ground. Either the positive jumper cable shorted to something, or the Positive cable was in fact hooked to the negative post, or the coach battery was internally shorted. But since the coach started thereafter, I have to exclude the third possibility.
 
I'm suspecting that the positve cable on my car slipped and made contact with a grounding.      I did have the right cable contacts in place + to +  and neg to neg. 
dave
 
BirdClemRV said:
I'm suspecting that the positve cable on my car slipped and made contact with a grounding.      I did have the right cable contacts in place + to +  and neg to neg. 
dave
Click to expand...

I had a similar thing happen to me years ago which really demonstrated to me the kind of current that can pass between a positive terminal and the frame of a car.  I dropped a ratchet while replacing the spark plugs on a V8.  The wrench fell right on top of the starter mortor's positive terminal... glowed red and spot welded itself in place!  I hit it with another wrench to break it loose but it was quite a demonstration.

Good luck...

Rick
 
I hope you didn't wipe out an alternator on either vehicle. As soon as you hooked up the negative cable to the motor home and noticed the spark you should have stopped right then and rechecked your connections. Somehow you had power on that negative cable and it had to be coming from somewhere.
 
30yrnavy said:
I hope you didn't wipe out an alternator on either vehicle. As soon as you hooked up the negative cable to the motor home and noticed the spark you should have stopped right then and rechecked your connections.
Click to expand...

I thought there would always be a small *spark* once you complete a connection with all the cables hooked up? 
 
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