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Re: [mad_scientist] Re: Ultracapacitors

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  • Vaughn Mcdowell
    It always seemed to me, rail guns in general, my guess is that the rail itself would be much lower impedance  than the  capacitor bank impedance plus the
    Message 1 of 4 , Dec 20, 2012
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      It always seemed to me, rail guns in general, my guess is that the rail itself would be much lower impedance  than the  capacitor bank impedance plus the leads connecting to the rail ; making the efficiency on the low side; I could be wrong about this. In high voltage systems any corrosion or bad contact would be over come by the highly conductive plasma arc; but then again arcing as viewed in rail guns would seem to me to be a loss.

      In the case of Ultracapacitors the ESR  may be low and several in parallel  might get close to that of the rail itself;  but it would seem to me that at such a low voltage any oxide or metal surface contact junctions may be large enough to prevent the required peak currents to achieve the needed force F = qV X B; I say go ahead and try it; but take great care in cleaning the surface and contact welding  problems associated. You never know till you try it.




      ________________________________
      From: "mrapol@..." <mrapol@...>
      To: mad_scientist@yahoogroups.com
      Sent: Thursday, December 20, 2012 9:15 AM
      Subject: Re: [mad_scientist] Re: Ultracapacitors


       
      The car battery idea is being tried by home experimenters. See http://www.youtube.com/watch?v=GPJao1xLe7w for example.

      Anybody know if these ultracaps are any good in a railgun?

      As for buying them, they come up on eBaynow and then at (semi)reasonable prices.

      Paul

      ----- Original Message -----
      From: AlienRelics
      To: mad_scientist@yahoogroups.com
      Sent: Thursday, December 20, 2012 8:32 AM
      Subject: [mad_scientist] Re: Ultracapacitors

      I wish I had some. I've never had any of those capacitors, although I understand the ESR is REALLY low.

      I don't know about them making a good car battery replacement. With a chemical storage battery, the output voltage stays relatively constant over a wide range of charge. Whereas with a capacitor, the voltage is a linear function of the amount of charge stored.

      Steve Greenfield AE7HD

      --- In mad_scientist@yahoogroups.com, <mrapol@...> wrote:
      >
      > I recently got my hands on a dozen Maxwell ultracaps, rated at 2.5 volts with a capacitance of 2600 Farads (yes, Farads). These were salvaged from hybrid vehicles but they're in good condition and can do more work. I'm thinking about using 6 of them to make a car battery replacement pack, but I'm wondering what to do with the rest. I have vague ideas about a rail gun, but I don't know if these ultracaps would be suitable. Any guidance?
      >
      > PBT
      >
      > [Non-text portions of this message have been removed]
      >

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