Selfrunning cold electricity circuit from Dr.Stiffler

[MarkSnoswell]

@Kator1

MPSA06 is available from West Florida Components on eBay http://shop.ebay.com/merchant/westfloridacomponents_W0QQ_nkwZQQ_armrsZ1QQ_fromZQQ_mdoZ

Do you have a link for that paper on the supercaps?


@hartiberlin and all

You can use the supercaps but you just have to take account of their particular characteristics when doing efficiency calculations.

[DrStiffler]

@All

I do not dispute the accurate description of what can happen with supercaps, but I will say that the charge when properly applied by an ESEC will remain on the test caps for over 24hrs with only a minimal 0.5 to 1 volt drop, which still reflects a CEC far in excess of 1. If I had a cap with 1ma leakage I would be looking for my money back!.

To stop this before it goes to far, the charge on the caps are dumped (cycle discharged) into an electronic load (monitored via computer) and what is presented is accurate.

@Stephan

Be careful of what you wish.........

[hartiberlin]

@All

I do not dispute the accurate description of what can happen with supercaps, but I will say that the charge when properly applied by an ESEC will remain on the test caps for over 24hrs with only a minimal 0.5 to 1 volt drop, which still reflects a CEC far in excess of 1. If I had a cap with 1ma leakage I would be looking for my money back!.

To stop this before it goes to far, the charge on the caps are dumped (cycle discharged) into an electronic load (monitored via computer) and what is presented is accurate.

Well sounds good, so your charge is real and not just some kind of surface charge...
With all your great test equipment you would have probably anyway detected this already, if the
discharge pulse into the nicad wire or load resistors wouldhave been smaller..

@Stephan

Be careful of what you wish.........

I hope you can accomplish this soon ! 

[MarkSnoswell]

@Kator01

Not to worry -- I have found the references to the capacitors -- just needed to search with the right terms -- Electrochemical Supercapacitor.  I note from this paper that the capacitance could easily be less than 10% of the rated DC value in the MHz range. http://www.imeko.org/publications/tc4-2007/IMEKO-TC4-2007-009.pdf

This paper concludes:

"The phenomenon of capacitance dependence on measurement current values is explained by a
complicated physical and chemical nature of the electrochemical supercapacitor charge storage. The
non-linear equivalent capacitance of the electrochemical supercapacitor porous electrode includes nonlinear
distributed double-layer capacitance and non-linear distributed Faradaic capacitance. These two
capacitances have different time constants. Therefore, if the electrochemical supercapacitor is charged
with high current the non-linear distributed double-layer capacitance is charged to a rated voltage faster
than non-linear distributed Faradaic capacitance."

These capacitors are fascinating -- as noted here http://www.ias.ac.in/currsci/dec252000/1656.pdf - they are characterised by two components; the electrical double layer capacitance and the pseudocapacitance. .. indeed, the equivalent spice model given in the first paper is quite alarming in it's complexity.

While I can find plenty of academic papers I cant find a summary reference on the behaviour and recommended use of the current generation of "car" supercapacitors -- does anyone know if and where this data is available?

thanks
mark.

[sparks]

    Capacitors are funny animals.  They must physically squeeze the heck out of the dielectric.   Especially if you're up around a coulomb on each plate.  No wonder they need to dissipate heat when used in an ac permanent split capacitor motor .