Without some form of bleeder resistor those caps should hold a charge for a while. I’m assuming you are using electrolytic?
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Without some form of bleeder resistor those caps should hold a charge for a while. I’m assuming you are using electrolytic?
Are there any safety issues with these capacitor based jump starters?
Some years ago I remember getting a boot from a large capacitor in flash pack. Wasn't funny.
The stop / start 'battery' in my RRS is a super capacitor. There has been a fair amont of effort been put into stopping people from 'getting at it', I assume for safety reasons.
That would have been about 400VDC and having had a boot from one of those I suspect it would have hurt (mine did). If you'd shorted it with a 14" crescent wrench you'd have seen a pair of "splat" marks on the wrench where you touched it with the capacitor.Quote:
Originally Posted by Ferret
If you touch a vehicle sized super capacitor you'll get the same tingle you get across a 12V battery if you are fat and sweaty enough. If you short it with a 14" crescent wrench you'll probably catch fire from the splatter and then have two halves of a wrench.
Short a 900CCA battery with something conductive and bad things happen. Short a super capacitor and that becomes exponentially worse. Like I said, I fused (melted) a 1000A shunt with a super-cap bank. So I suspect they've got it hidden away to prevent accidental "bad things" happening. Not electrocuting a human, but maybe not setting them on fire if they short a spanner across the terminals.
Hi,
I upped the power of a photographic studio flash head years ago. The capacitor in that was scary. I clipped a 40W 240V lamp across it for an anti zapp protection.
Cheers
Caps, the big ones, can kill. They can deliver all of their current instantly. Anyone who has mishandled an old CRT can attest to that. They can bite weeks after the thing was turned off.
A suitable light globe is a reasonable way to discharge them. A dedicated discharge tool with a big high wattage resistor is better. ( high ohms numbers are important but the high wattage means that the resistor won’t just burn out the first time you use it).
Capacitors are dangerous. But they’re amazing as well.