Capacitor-bank safety issues

Okay, so I'm going to be the wet-blanket old guy.... Has anyone considered adding a topic to this group (or an I'ble) on electrical safety with supercaps? Even the low-voltage ones put out tremendous current, enough to put you into convulsions or stop your heart (50 joules) if applied correctly. These devices are amazingly cool to work with -- better than batteries when you need high current, outstanding AC line filters, and terrific party toys when you need some bang for your buck. They can also turn around and bite you on the arse without warning...

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westfw8 years ago
  • Even the low-voltage ones put out tremendous current enough to put you into convulsions or stop your heart (50 joules) if applied correctly.
At 2.5 to 5.5V? "applied correctly" would need to involve cracking open the chest at applying electrode directly to the heart muscle! I=V/R, and R is pretty high for most biological constructs. (the "safe" current is usually quoted at less than 20mA, which means you'd have to get the resistance though the body circuit down to WAY less than 1k ohms.

I'm a lot more worried about the people playing with camera strobe guts.
Camera strobe guts do seem to be the most accessible and potentially dangerous course of such components since anyone can ask for them, people clever enough to build the circuit tend to know better...
I one got nipped by one of those things, NOT FUN!
I would have thought that Cap banks weren't as much of an idiot worry since every 'ible involving them tends to stress the dangers and powerful ones take a modicum of intelligence to assemble in a manner that will let them function... Though on that note exploding and venting caps are bloody dangerous, lots of energy let out in another way...
  • every 'ible involving them tends to stress the dangers
I dunno. I think people think they might get a painful shock, or end up like a Taser'ed criminal, twitching on the ground in somewhat amusing fashion. HV capacitor things get labeled "taser" without people realizing how much technological effort goes into making a REAL Tazer non-lethal (most of the time.)
The thought that one ZAP might leave them lying on the other side of the room with their heart stopped cold doesn't match the expectations created by the media...
I forgot about tazer 'ibles, they aren't safe, nor clever, in fact I recently found out the painful way that you don't actually need to remove the tube or anything to get a shock, I foolishly used my finger as an experimental diffuser, it worked nicely but I got a good zap off the tube aswell...
Your right about them exploding and venting a big capacitor can paper the walls a new color complete with shiny bits of metal... And if it's an old capacitor it'll also fill the room with P.C.B.s
I'd say a big cap bank inside a heavy rated pipe made of ABS or PVC would be a safe way to keep it from both accidental shorts and limit the blast damage, if the ends were open it'd simply direct the blast out the ends, plus it's not a bad for factor for the cap bank, I'd say that under normal operation say 90% of maximums wouldn't be a worry for most things but some people like to overcharge caps, so mounting the bank on a bit of wood you can slide in and out would probably be a good way to do it...
Sandisk1duo8 years ago
It's pretty safe... super capacitors store HUGE amounts of amperage, not voltage, Super caps usually have relatively high internal resistance even if you were to stab yourself with both pins of the capacitor, it wouldn't kill you, maybe if it went into very close proximity of your heart, then you might die. 50v is required to penetrate skin, i can't remember if that's wet or dry
must be dry because a 9V can tingle on wet skin and let me say that 12V to wet skin can sting...
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