Komatsu P C 300 - Electrical Short Circuiting / Earthing of Battery Positive Terminal

[adjuster]

The above excavator was working besides a face of the hill, due to muck sliding a boulder rolled & fell over the Battery Box top cover which caved in & ruptured the Positive Terminal Cable insulation & a short path from the Positive terminal was formed with body of Excavator resulting in overheating of several wiring looms / bunches & damaged sensitive electrical & Electronic components.

How this occurrence can be explained when the negative terminal is already earthed with the body of Excavator?

adjuster (M S Sainani, Loss Adjuster, Udaipur, India)
+ 91 9414168144

 

[Mjrdude1]

The negative cable is grounded (earthed) to the machines frame, when any part of the frame or attached metal parts come into contact with the positive battery terminal, it causes a direct short at that point. It should have melted and arced at the battery post.

The wiring harness damage was caused by the charging system sending power through the harnesses which power the machine. With a direct short at the battery all electrical systems which were energized can become shorted which in turn builds heat and causes damage to the electrical system. The electronic components are especially sensitive to damage caused by a direct short. In many cases the heat generated will cause a fire and burn the machine beyond repair.
I am assuming it was running when the boulder hit it of course.

 

[Delmer]

I've never seen anything like this, but I've only seen a couple of similar shorts, so I'm pretty limited experience wise.

Possibly the arcing caused electrical spikes that damaged the components? or the alternator voltage regulator is connected to a different point (that was "closer" to the short) than the alternator output, causing the alternator to put out too much voltage for part of the system (wild ass guesses)

If you're trying to determine whether this is a legitimate claim or not, I think you'd have to prove another cause of the damage to deny it. One common cause of electrical component damage is welding on the machine. Were there any new welds, fresh paint, suspiciously new or changed buckets?

 

[John C.]

Contrary to popular believe, amperage flow goes from negative to positive. In electronic systems built today everything controlled by a computer is always hot and becomes active when the computer completes the circuit. Diodes control the direction of flow in many circuits and the huge back flow of amps burns through them setting up a short which heats up wiring and burns out computers and controllers.

At any rate a rock fall crushing a battery compartment would in most instances cause severe damage to the house besides the electrical issues. That almost always results in a total loss of the machine. If I were adjusting the loss I would want to see the actual damages to the house and an up close inspection of any burned wiring harnesses before making a settlement offer.