Having fun with big ultra capacitors

in components, parts by DP | 12 comments

Here’s a video by Afrotechmods: Fun with ultracapacitors!

So I recently got hold of some 2600F (no that is not a typo) ultracapacitors with an insanely low ESR of 0.7 milliohms, meaning they can discharge hundreds of amps even at low voltages. This video shows you some of the mayhem I got up to, and teaches some important capacitor formulas along the way.

Via PCBheaven.

This entry was posted in components, parts and tagged .

Comments

  1. A.Lizard says:

    Wait until CNT or graphene ultracaps for vehicle energy storage become available.

  2. krye says:

    You have to be nuts to play around with that many joules. It borders on irresponsible. Just to put things into perspective, when the doctors hit you with a defibrillator, it’s usually between 100-200 joules. They can go as high as 400, but never more. And those rubber gloves you use when cleaning the toilet will do nothing to act as an insulator. You should use the thick black heavy ones you see the guys up on the telephone poles using.

    • *langwadt* says:

      defibrillators are much higher voltage, 10V isn’t generally considered dangerous, I’d be more concerned about behing hit by molted metal

      • Jack says:

        10V IS dangerous to a human is applied correctly. The voltage that is generated across the heart is the main factor as to stopping it. This voltage will only be dropped when a large enough current can be conducted through the heart muscle. Usually, 10V DC is harmless due to the limited current available to go through the terminals and skin resistance but in this application, it can be.
        So be careful.

      • fonz says:

        while we are nitpicking, it is current through the heart that is dangerous some where between 20mA AC and a few hundred mA DC is likely to kill you

        what voltage is required of course depends on whether you touch it with dry hands or put needle through the skin

        “safety extra-low voltage” goes to something like 50V and is I believe is considered safe for
        accidental touch

    • Parker says:

      “It borders on irresponsible.” Why do you care what he does? It is not like it is hurting you.

    • eLLi says:

      No, he is not wearing those gloves to protect him from the electricity, but to protect his hands from all the flying burning stuff…

  3. katjap says:

    Too bad he doesn’t have the 20A constant current supply i picked up at a yard sale this weekend :P

  4. erdabyz says:

    There are a few misconceptions in some of the coments. Ohm’s law prevents you from getting zapped with those capacitors. Capacitors are constant voltage sources. No matter how much current they can deliever, 10 volts are 10 volts and 10 volts DC are safe by most standards. What’s the difference between touching one of this and douching the terminals of a car battery or touching the terminals of a freshly charged 3S lipo battery? Body’s resistance is higher at low voltages (and we’re talking about DC) and with 10V the current that could go through your body is barely noticeable and insuficient to cause significant trouble in most cases, even when wet.

    The problem with this caps could be a case where the two leads come together very close to human skin or if some redneck decides that doing the tongue-test to an ultracap is a good idea or some events like those which would blow up the contact area.

    I mean, yes, these things are dangerous and they store too much energy inside, but the rate at which they can deliever energy to your body is limited and electrically speaking a pair of rubber gloves would get you more than safe. I’m much more scared about low value high voltage capacitors found in places such as flash lamp drivers. Those “only” store several joules but if you tocuhed one they would literally blow your fingertip off.

    • Point being, resistance of human skin is on the order of a few kohms per linear inch (let’s not model sheet resistance, but say linear resistance where arms roughly equal wires). 10v, unless applied VERY unfortunately and likely UNDER the skin, is not going to do any damage. Also, I’ve determined experimentally for science the following body-contact currents at 10v.

      light touch on banana connectors, fingertips – 10-20µA
      full tip grip on banana connectors (grasping), fingertips – 80-100µA

      tongue test – light touch on banana tips – 1-1.5mA. >1mA is quite uncomfortable, but not painful. >2ma I am not willing to try. The 9v battery test has only ever netted me 1mA.

      Point being, it’s the fact that your tongue is substantially lower resistance. In theory, there’s no problem doing the tongue test on this cap array. If you push hard and make good surface area contact, you’ll get more than 1-1.5mA. Which would probably be enough to kill you, were it across a vital organ. Luckily, your tongue isn’t. That said, a healthy fear of/respect for dangerous things never hurt anyone, so I won’t be trying it.

      Another interesting point is that skin conductance is wildly non-uniform. For example, something I just discovered. With a light touch of one lead on my fingertip (same conditions as first test) and a light touch of the other banana tip on my outer arm at the elbow, either side, or on the elbow itself, I measure not more than 1µA. When the probe tip is moved to the crook of my arm though, directly opposite my elbow (presumably where the skin is more moist and thin), I get upwards of 10µA, more or less depending on the location within that regin.

      Anyway, claiming a definitive model for human body shock risk is pretty silly, though it’s safe to say that to get current across the heart (generally assumed to be the primary mode of fatality) you’ll need arm-to-arm transfer, and luckily hands and forearms seem to be the poorest entry points for current, based on my tests.

      Point being, you’re not going to shock yourself with this thing, no way. But you could easily burn yourself on shorted metal, or take slag to the eye. It’s a big mig welder.

      • Also, re: flash capacitors. The leads are so close you’d be hard pressed to get fatal cross-heart current, but I think you’re right to be more afraid of a shock from them than this thing. I’d say they’re more dangerous. They certainly hurt like a M-Fer.

  5. Steve says:

    Don’t be a pussy, these things are fun.

    I have 5 of them wired in series. It can liquify a penny, and vaporize just about any trace or component on a PCB.

    Charging them is interesting since when empty, they look like a direct short to my power supply.

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