mc2fool wrote:GoSeigen wrote:Worth adding that those capacitors are incredibly dangerous, even the garden shed version could probably kill you if you touched the wrong bits, so safety is a big issue.
While it's true that, as the old saying goes, it's mills that kills and volts that jolts (mills = milliamperes, i.e. current), and it's generally reckoned that 100mA is lethal, with as little as 10mA being able to cause muscle contractions, these 400F capacitors are just 2.7V each.
So, with the guy having wired eight in series the bank will be charged to only 21.6V, and while the effective 50F of the bank will store a lot of coulombs, the "mills" that flow out of it will depend on body resistance and it's extremely unlikely that you'll get even a mild shock from the 21.6V ... unless you connected one side to, say, the inside of your mouth and the other side to another soft and moist part of your anatomy.
For someone who was into electronics in his yoof, when 400 micro Farad electrolytics were considered big, these supercapacitors are kinda gob smacking ... indeed, I remember our physics teacher at school (quite a few decades ago now!) telling us that a one farad capacitor would have to be the size of a house ... although maybe he was talking about Leyden jars ....
Perhaps it's the thought of an accidental short-circuit across the capacitor terminals which causes alarm. A short across battery terminals would not be good news for sure, but I suspect a short across a charged 400F capacitor might cuase a sudden and significant explosion to the detriment of the capacitor and any nearby human.