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Re: drsstc questions

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

Found a couple giant (biggest I've seen at 4.5" in diameter and over 10" long) 450v 12000uF caps. The ESR is only .025 ohms. Would these be overkill or is there such a thing as "too big"? After blowing up a relatively small 25v 4700uF cap with AC like a firecracker (just for fun, but wouldn't do it again since it made my basement stink for a week) these things almost scare me considering they store up to 2.4 kJ each. How suitable are these for exploding wires/water? Would near dead shorts (~18,000A) destroy them? The guy that sold 'em to me for $50 each said he'd keep his eyes open for smaller ones if these won't work.
As for the batteries, I know what your talking about Terry. A fully charged single cell will melt a 22 awg magnet wire in a second or two and make the battery quite warm just doing that. I plan to meter the output to make sure it doesn't go over the 5A discharge rating. The ones I got are the 18650's from here: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=990.

Thanks for all the responses,
Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, March 28, 2005 1:28 AM
Subject: Re: drsstc questions


Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

At 11:03 PM 3/27/2005, you wrote:

>
> 1. Could these things be ran w/o the big electrolytic caps if it was > ran
> from a 720v Li ion battery pack (5A max continuous current draw)?

Afraid not.

 Or are
> they more than just for filtering?

Indeed they are!  They have to supply several hundred amps for a few
hundred uS (typically 150uS for smaller coils).  I dont know if a
battery will do that.  Also, compare the ESR of a giant electrolytic
with that of a battery.  I dont know the ESR of those kind of
batteries, but i have a feeling its pretty high if its only rated 5A
continuous.

I was cleaning files yesterday and I guess I deleted all my Li-poly explosion videos :-( But search the web...

They can supply thousands of amps till they explode like a hand grenade!! They keep doubling the peak current output of the technology every few months!! Illeagal to ship by aircraft now since they almost fried LAX... Lot of "regulations" for Li-poly went into place in October... All that burning elemental lithium flying all over the place... Hard to put out...

But "I" would not touch the goofy battery thing... DRSSTCs are complicated enough already. Run it off plain old AC and get a UPS if you want to run in the middle of the desert... If you are a battery guru and want to go that route, then more power to you ;-))

Cheers,

        Terry