Be careful with large 12 volt batteries! (accident story)

[gksudo]

so when I was putting together my driver, I accidentally bumped my 12v battery's wires together with my elbow.

Of course, short circuits are bad, so I quickly tried to yank off the wire the instant I heard the spark. As you know, when you short circuit a lot of power, it welds the connections. Thats precisely what happened. Right as I grab the wire, all the coating on it vaporised. You can imagine by this point i'm like "OH FFFFF oh FFFFF". Pretty much XD

At this point I grab the pliers and try to rip the wire off the contact, no good, its very stuck on there(even though I merely wrapped the wires on the leads of the battery.) I decided to try and cut it with the cutters, which finally stopped all the panic.

yeah... so after all that I was left with a severe burn where I grabbed the wire. Funny how all this happened in a little over 5 seconds.

Here's what I was dealing with:

Battery:

The wire after the short:

Closer image:

Lesson to be learned? Be more careful with batteries of that size, use in-line fuses, and don't play with electricity when you are just waking up and not focused. XD

 

[Benm]

Auch!

I fully get how your instinct tells you to grab hold of the shorting wire and try to yank it off, but as you found out, thats not that easy. Once the isolation starts smoldering there is litte chance of fixing it with bare hands, and wire cutters are called for indeed.

If it happens again, you can also use a screwdriver or something similar as a lever to break the shorting wire. This works fine beause a wire that hot is maleable enough to break with little force - just don ever use your hands!

 

[Seoul_lasers]

Yup. Those batteries can deliver some serious current. Good thing you didn't get too bad a burn. lesson learned. What you got there is called a running short. This used to happend back when wires were made of Aluminum and fuse boxes were protected using the old screw in fuses. Short would start on and extension chord and heat the lossy high resistance wiring... short would run behind a wall and cause a structural fire.

 

[gksudo]

Well the good news is my burn isn't noticeable anymore!

Strange how the battery is still over 12 volts after a dead short

 

[Cyparagon]

A friend of mine was jump starting a car once with 10awg cables (which is kind of a bad idea already). He walked away for a few minutes and when he came back, the entire length of the cables was on fire. OOPS. "plus" was touching the chassis.

 

[BShanahan14rulz]

lead acids are tough :wave:

Lithium chemistry is not as forgiving ;-)

 

[ShortyInCanada]

Oooooooooooooo.
I didn't need to remember that !
I was using a full size car battery as a temporary power source for a 12V 7A "beacon" lamp.
Accidentally allowed a piece of solid core 14AWG wire about 15" long short across the terminals.
Yup. Grabbed it with my hand and pulled hard to break it free.
Got the burns in the creases of all my fingers on the left hand. (Made a bit of a new "crease" in my baby finger.) Good ones too ! Blistered and swelled up for days. VERY nasty business. Lucky I'm right handed. Sure does making taking a leak a lot more troublesome though.
Glad you didn't suffer any serious damages !

Even though it was 20 years ago now my hand feels funny...

 

[Seoul_lasers]

Oooooooooooooo.
I didn't need to remember that !
I was using a full size car battery as a temporary power source for a 12V 7A "beacon" lamp.
Accidentally allowed a piece of solid core 14AWG wire about 15" long short across the terminals.
Yup. Grabbed it with my hand and pulled hard to break it free.
Got the burns in the creases of all my fingers on the left hand. (Made a bit of a new "crease" in my baby finger.) Good ones too ! Blistered and swelled up for days. VERY nasty business. Lucky I'm right handed. Sure does making taking a leak a lot more troublesome though.
Glad you didn't suffer any serious damages !

Even though it was 20 years ago now my hand feels funny...

I am going to one up you.. sorry.
I used to work for Dockyard here in Victoria. One of the young (high density..duuuh) officers on our logistics team decided to "test" a very large 144V 10KW battery bank battery with a file to see if it was holding a charge. We were all sitting around having lunch when we heard a fairly loud "BANG" and saw a young officer with black soot all over his face running towards the medical station. His clothes and hair were quite singed.
Apparently, though I didn't see it, the file violently vaporized on him from the short circuit current. The smell of cooked flesh was readily apparent. Luckily we were BBQing that day so it wasn't too bad.... Luckily he kept all his fingers and didn't become part of the circuit.
The next day we were all briefed about the idea of safety around the base.

This guy was lucky he wasn't blinded by the flash from the vaporizing file and lucky it contacted while his hand was not actually physically holding on to it. (I guess the office didn't get a good connection the first time???) The officer needed extensive skin grafts on his right hand and flash burn treatment to his face. Think welders tan/burn from short arc

 

[gksudo]

Oooooooooooooo.
I didn't need to remember that !
I was using a full size car battery as a temporary power source for a 12V 7A "beacon" lamp.
Accidentally allowed a piece of solid core 14AWG wire about 15" long short across the terminals.
Yup. Grabbed it with my hand and pulled hard to break it free.
Got the burns in the creases of all my fingers on the left hand. (Made a bit of a new "crease" in my baby finger.) Good ones too ! Blistered and swelled up for days. VERY nasty business. Lucky I'm right handed. Sure does making taking a leak a lot more troublesome though.
Glad you didn't suffer any serious damages !

Even though it was 20 years ago now my hand feels funny...

I am going to one up you.. sorry.
I used to work for Dockyard here in Victoria. One of the young (high density..duuuh) officers on our logistics team decided to "test" a very large 144V 10KW battery bank battery with a file to see if it was holding a charge. We were all sitting around having lunch when we heard a fairly loud "BANG" and saw a young officer with black soot all over his face running towards the medical station. His clothes and hair were quite singed.
Apparently, though I didn't see it, the file violently vaporized on him from the short circuit current. The smell of cooked flesh was readily apparent. Luckily we were BBQing that day so it wasn't too bad.... Luckily he kept all his fingers and didn't become part of the circuit.
The next day we were all briefed about the idea of safety around the base.

This guy was lucky he wasn't blinded by the flash from the vaporizing file and lucky it contacted while his hand was not actually physically holding on to it. (I guess the office didn't get a good connection the first time???) The officer needed extensive skin grafts on his right hand and flash burn treatment to his face. Think welders tan/burn from short arc

... Ok that kind of stupidity hurts to listen to. And if it didn't vaporize and got stuck? Then what? D:

One time in auto shop in high school, I was sitting on the back desk playing with test crcuits, and this kid comes over and drops a crow bar across the car battery next to me.

I ran out the door yelling " no Fffffffingway man!!". Stumbling over whatever was in my way.

Luckily the battery was weakly charged.
He got it off the contacts 10 seconds in.
The teacher said something like "what the hell you doin?" to the kid " your gonna kill yourself!". The kid said "that shit was heatin up yo!".

Yeah. Of course it was heating up...damn dude why must these dangerous people be allowed near dangerous things?

 

[Somedude]

Thats called electric strip heat :angel:

 

[Seoul_lasers]

... Ok that kind of stupidity hurts to listen to. And if it didn't vaporize and got stuck? Then what? D:

One time in auto shop in high school, I was sitting on the back desk playing with test crcuits, and this kid comes over and drops a crow bar across the car battery next to me.

I ran out the door yelling " no Fffffffingway man!!". Stumbling over whatever was in my way.

Luckily the battery was weakly charged.
He got it off the contacts 10 seconds in.
The teacher said something like "what the hell you doin?" to the kid " your gonna kill yourself!". The kid said "that shit was heatin up yo!".

Yeah. Of course it was heating up...damn dude why must these dangerous people be allowed near dangerous things?

Well, now that I think about it, it most likely wasn't the battery that did the vapourizing of the file, but the massive 3 phase charger charging the battery that did this. The fork lift battery was out of the unit being re-charged at the time in the other room.
Have a look at how explosively copper becomes when about 100A or so is pump through it
at 480V. This is a little bit more dramatic then our forklift battery event, however being smaller it can still do a great deal of damage.

480 volt 3-phase Arc Flash Demonstration - YouTube

Now imagine your face next to that.

 

[Bionic-Badger]

Ouch, yes, I accidentally touched the two terminals of a deep-cycle battery for a UPS with a wrench as I was wiring it up. One giant spark later and the tip and side of the wrench where it made the connection were quite damaged. I was lucky enough to be able to pull it back in time and not get hurt.

 

[Benm]

Strange how the battery is still over 12 volts after a dead short

Well, its not really a dead short from the battery perspective. Perhaps that wire had a resistance of 0.1 ohms resulting in 120 amps of current. That be 1440 watts heating it up, but discharing the battery at 25C or so. Its probably a lot more that what it is supposed to deliver, but most lead acids can do this easily for a short period of time.

Another thing that 'helps' is the wire heating up, since that increases its resistance considerably (like in a lightbulb).

 

[Cyparagon]

There's also the internal resistance of the battery

 

[ShortyInCanada]

"I am going to one up you.. sorry. "

You know, I'm glad I'm not the stupidest one !
When it come to being an idiot I will be happy to place last as often as possible. I will keep making the list though, as it means that things are staying interesting for me. Whether I plan it or not...