Many of you have heard that Lew McFadin (W5DID), working with Steve Bible (N7HPR) and Steve's colleagues (especially Keith Curtis) at Microchip (the PIC people) have been working on a next generation power conditioning system. The basic idea is to have a power charge/discharge conditioner for each cell of the spacecraft's battery pack. This will allow the use of several different battery technologies (NiCd, NiMH, LiIon, etc) and also some of the new "super capacitors". Some of you who were at Dayton may have seen the breadboard mockup of system that Steve brought and Lew was showing. Lew was also showing some ~2000 Farad(!) 3 volt capacitors (some of us dubbed them "flux gate capacitors").
The SuperCap developments have been exploding of late. One immediate service is for regenerative braking in hybrid and electric vehicles, since the capacitors seem to be able to withstand a (virtually) infinite number of charge/discharge cycles, and then can "soak up" & discharge huge currents -- must faster than any chemical batteries can do. Batteries store watt-hours of energy, while capacitors handle large numbers of watts of power. One German light-rail system employs a total of 600 2600Farad capacitors for regenerative braking. Some US electric buses have capacitor banks with 144 18Farad capacitors that deliver 400 Amps at 360 Volts.
Today I received the 11.15.07 edition of Electronic Design magazine, and there is an interesting technology review paper entitled "Get the Lowdown on UltraCapacitors" starting on page 45; the article is available online at http://electronicdesign.com/Articles/ArticleID/17465/17465.html.
Starting on page 50 (the 3rd page of the online version) The AMSAT/MicroChip effort is described along with schematics (figure 6, also http://electronicdesign.com/files/29/17465/Figure_06.jpg). The closing paragraph (which doesn't mention the planed use of these concepts on Suitsat2) says:
Microchip worked with AMSAT-NA, the not-for-profit private
organization that develops
amateur-radio satellites. AMSAT’s next big project, the Eagle
satellite, is slated for
launch in March 2009. To make Eagle function for decades, it will have
a power system
based on this work that combines solar panels, lithium-ion batteries,
and ultracaps
in an integrated power system that will optimize the use of each of
those components.
Pretty good publicity!
73, Tom