Battery safety

Hi guys, I was wondering if it's dangerous to touch two wires hooked up to a 9v battery to each other. They heat up really quick, could they make the battery explode or do something else bad if left like that for any long period of time? I tried to search for the answer, but couldn't find it.

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westfw9 years ago
Just a few words of caution...
Battery technology has improved a lot in the last few decades. It used to be pretty difficult to hurt yourself with standard (AA-C-D-9V) batteries. But nowadays with alkalines and rechargable batteries, it's a lot easier. You can easily burn yourself short-circuiting a battery with a wire. You might generate enough heat in the wires to cause fires. You might be able to cause a battery to overheat to the point where it "bursts." This is usually a pretty trivial event; MOST battery technologies still are based on water as a main internal ingredient, so that when they burst the effects are limited to a small pop, a leakage of rather caustic chemicals, and the stoppage of normal battery function. I've also seen high-voltage "shocker" type circuits that say "this is safe because the battery cannot provide enough current to reach dangerous levels at the output", and I wonder just how safe they are with modern batteries...

However, the "Lithium Ion" and "Lithium polymer" batteries used in many modern rechargable devices (cell phones, lap-tops, mp3 players, cameras, etc) need to be mentioned. In these batteries, the internal liquid is flamible, AND there are some other chemicals that react violently with each other at high temperatures. Given suitable mistreatment, these can "vent with flames" rather spectacularly (though it's not quite an explosion.) The most common mistreatments that cause this behavior are improper charging or physical damage, leading to short circuits INSIDE the battery, but its rumored that external shorts are bad news as well. A rechargible battery PACK usually contains numerous protective devices designed to prevent such incidents, but your experiments might lead you to, say, taking apart "broken" battery packs and using the internal cells. In which case the level of care you take needs to go upward a notch or two...
DJ Radio9 years ago
that is actually known as "short circuting", and its not really safe, but i read that in an old book, so it could be safe today. It drains the battery fast....
Lithium Rain (author)  DJ Radio9 years ago
No, I looked up short circuiting and that's definitely not it.

But it is true that this drains it very quickly.
Hi, Adrian. What you've described is precisely a short circuit; in fact, it's the very first example in your Wikipedia link :-)

You've connected the postive and negative voltage terminals with no load. The wire and the battery will heat up, for sure (since it has non-zero resistance and you're sucking lots of juicy current through it). A regular electrolytic or alkaline battery won't explode, but you will drain it to zero voltage pretty quickly.
Lithium Rain (author)  kelseymh9 years ago
Oh. Haha, I'm an idiot. Sorry, DJ... I see, thank you for explaining it! I noticed I could make cool sparks and even some kind of apparent magnetic effect if I touched both wires to an altoids tin. But it stopped working suddenly. Musta drained it as you said.
Magnetic effect? If you got sparks at the same time, it's more likely you created a small weld (either with actual welded metal, or with oxidised patches overlapping).
That's exactly what it is, a 9V has the current capacity to do so, most things do, I saw this effect a lot during some recent experiments, I couldn't tell if it was welding or oxidation but the bond can be quite strong so welding of tiny proportions could be it...
Lithium Rain (author)  killerjackalope9 years ago
=O Cool!

I called it! I called it!

Don't anybody go making my ible! :D
Linux already did it, not only that but it's useless in reality because it's a very weak weld most of the time, plus I'm not actually sure it's a weld or if it's oxidation with two metals, like just being glued by oxidation...
Lithium Rain (author)  killerjackalope9 years ago
Really? I'll have to see what he did... Hmm. I'm experimenting with more batteries, maybe that will help-I'm not giving up quite yet, not because I don't believe you, just because I want to see for myself.
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