Re: Ultracaps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: David Sharpe <sccr4us-at-erols-dot-com> 

Hi Mike

Tesla list wrote:

>Original poster: Mike <megavolts61-at-yahoo-dot-com>
>I wonder if these could be used in quarter shrinking or rail gun 
>applications...assuming you had lot of them in series

They can handle pulse power (currents to 1000A for starter motor assist 
true enough).  Now for
the ugly truths...
1.  They are rated at only 2.5V per cell, (newer to 3.3V max) so you think 
an MMC array
      soldering is bad, how long would it take you to solder together 4000 
of them for a paltry
     10kV?  Not to mention power connections to handle that current.
2.  Capacitor is a Double Layer system closer akin to a battery then an 
electrolytic capacitor.
     with polaity separators etc.  Plus fact that at least some of the 
higher energy units use
      electrolyte material that is hazardous (toxic and potentially [no 
pun] explosive).
3.  You can over voltage them but life drops as a power exponential to over 
voltage normalized
      to rated, (10% OV cuts life almost in half).
4.  They ARE NOT designed for ringwave or voltage reversal.  Their voltage 
reversal tolerance
      is 0.001%.  If you attempt to reverse polarity of capacitor, it 
either looses functionality or
      blows up!  So even in pulse discharge applications they should be 
approached with MUCH
      caution.

Their strong suits are:
Very large energy storage per unit volume, Russians have been using for 
many years to start
    railroad locomotive diesels electrically at -40F.   Also applications 
for military  (pulse power,
    short term memory storage, electric/hybid vehicle power assist).
Large WH per unit liter means some newer devices approach power density of 
a lead-acid
    battery.

Not very useful or practical IMO for Tesla or HV pulse power applications.

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA