Feb 192010
Its safe to touch both terminals of 12 V car battery but if a metla tool is dropped it can be dangerous. WHy? I can only think of one thing.. The metal tool will get very hot and so if mechanic touches it, his hand will be burnt.. Can anyone give me any other suggestion if there is any?
No reason other than the one you have outlined. It is naive to talk about electrical shock with 12V system.
Automotive batteries contain quite a bit of energy
The voltage is low; most people won’t feel electricity (shock)
However
In normal operation it produces hydrogen; a spark in the vicinity will ignite the gas and cause an explosion of the battery
The force of the explosion will cause major property damage and personal injuries.
It is also very dangerous to work in any electrical circuits with jewelry like ring bands, chains, as these could slip come in contact, get red hot and severely burn whatever skin is there!
Anita
A lot of wrong answers. You will not get a shock. The tool will get very hot and may explode, as may the battery. You will have lots of heat and sparks and smoke, it will be obvious that something is wrong as soon as the tool touches both terminals.
There is also the possibility that the tool is not making a good connection to one of the terminals due to dirt or grease, but when you touch it that increases the pressure or moves the tool slightly and makes a good connection, at which time you will have sparks, heat, etc.
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Because short circuiting a car battery is dangerous. Actually, short circuiting ANY battery is dangerous. It generates a LOT of heat and can cause the battery to explode. In particular, a metal tool that touches two of the battery terminals can cause so much heat, it essentially welds to the battery terminals preventing you from removing it… And then the car battery will continue to heat up and will likely explode.
If you have a metal tool touching both terminals of a charged auto battery, you will have a wonderful display of electrical sparks and a fabulous short circuit between the two posts – noise, sparks, smoke.
A metal tool cannot just sit between the two terminals with nothing happening until a person touches it. The metal certainly may be hot, but the other danger is that if you were to grab that tool, the current might divert through your body to ground, giving you a very nasty shock.
If you are holding a metal tool in one hand, with that tool touching a battery terminal, then you touch the other terminal, all of that current will flow from one hand to the other in a short circuit – across your chest and heart — really, really bad news.
There are two issues, which have been mentioned by others and yourself. You are correct that the tool can get very hot, maybe red hot depending on the circumstances, and also the battery could explode due to both hydrogen + arcs or overheating of internal connections and electrolyte. There is no issue with electric shock.
There can be hundreds of amps flowing, so there will be arcs like a welder, and very likely the battery lugs will melt, as well as chunks of the tool. I have seen this. You will certainly know of the situation if it occurs, it is not a passive thing.
I think what you imply is right.
Yes the tool could get very hot due to the high amperage that could flow through it — so you could burn your hand.
Secondly ,if the tool was not quite making the circuit, then moving it could produce a lot of sparks — you might get one in the eye .
What you won’t get is any significant electric shock — you have too high a resistance for any “dangerous” level of current to flow through you to ground.
A car battery can put out hundreds of amps into your starter, into a dead short a lot more.
Since the metal tool is very low resistance, a lot of power gets dissipated in the internal resistance of the battery itself, so the battery may explode.
Metal is a CONDUCTOR OF ELECTRICITY!!!!!!
the heat is the main thing, but in an auto garage any spark you get might be dangerous too. not too much danger, but there is some.
you get zapped! plus you can ruin the battery.