Batteries

On May 18, 1:11*am, "Brian Gaff" wrote:
Hmm, well, If these are the same as the domestic sort, I have found that
although in the main they are reliable, using them in series is a problem
unless they are matched or you have some way to figure out when the first
cell goes flat. if you don't do this then you reverse charge the cell and
eventually it kind of turns into a resistor!

Not exactly the same.

STS-132 Press Kit

More information at http://microgravity.grc.nasa.gov/SpaceOps/ISS/EPS/


and in the PDF at web.mit.edu/murj/www/v11/v11-Reports/v11-r1.pdf.

I can't do a complete description of the pictures for you, Brian, but
the cells are domed cylinders with connecting straps at the ends that
are visible. There also appears to be a finer harness running among
the cells and going to a box in the box; I'm guessing this has to do
with monitoring individual cells, perhaps for temperature.

The PDF refernces Dalton and Cohen, I believe, and that paper is
available from IEEE; the abstract is

"International space station (ISS) electric power system (EPS)
utilizes nickel-hydrogen (Ni-H2) batteries as part of its power system
to store electrical energy. The batteries are charged during
insolation and discharged during eclipse. The batteries are designed
to operate at a 35% depth of discharge (DOD) maximum during normal
operation. Thirty-eight individual pressure vessel (IPV) Ni-H2 battery
cells are series-connected and packaged in an orbital replacement unit
(ORU). Two ORUs are series-connected utilizing a total of 76 cells, to
form one battery. The ISS is the first application for low earth orbit
(LEO) cycling of this quantity of series-connected cells. The P6
(port) integrated equipment assembly (IEA) containing the initial ISS
high-power components was successfully launched on November 30, 2000.
The IEA contains 12 battery subassembly ORUs (6 batteries) that
provide station power during eclipse periods. This work discusses the
battery performance data after eighteen months of cycling."

(The google snip for that is "The battery. ORU (see Fig. 1) is
designed to operate for 6.5 years, with a mean-time-between-
failure ... Each battery ORU also mntains a letdown resistor .")

This paper appears in: Energy Conversion Engineering Conference, 2002.
IECEC '02. 2002 37th Intersociety
Issue Date: 29-31 July 2004
On page(s): 106 - 113
ISSN:
Print ISBN: 0-7803-7296-4
INSPEC Accession Number: 8245289
Date of Current Version: 14 February 2005

There's another Dalton and Cohen, NASA/TMm2001-210983, but that's a
much briefer description of starting up the battery systems; the PDF I
got from the Florida Today site wasn't a good enough copy for me to
read the labels in the drawing.

There is a proposal for Lithium Ion modules: "The International
Space Station (ISS) presently uses nickel-hydrogen batteries to supply
power during the eclipse (or dark) phase of its orbit. Once all four
of the photovoltaic modules are deployed on-orbit in 2009, the ISS
will have 24 batteries consisting of 48 battery Orbital Replacement
Units (ORUs). The current program has enough spare nickel-hydrogen
battery ORUs to last to the end of the mission in 2015. If the ISS
mission is extended beyond 2015, additional spare batteries will
be needed to replace those battery ORUs already on-orbit. Because
of obsolescence concerns, any such future spares will contain lithium-
ion cells instead of the current nickel-hydrogen cells.

In order to save on battery development costs, the ISS is looking to
the Constellation Program for potential collaboration. The NASA Glenn
Research Center was tasked by the ISS Program to perform a trade study
to determine if a common ISS/Constellation lithium-ion battery module
is feasible. "
(20090022068_2009021499.pdf from NASA servers)

(As an aside, my search turned up stuff about Orbital Express
transferring a battery ORU from Astro to NextSat.)

There may be more in technical reports, but that's what I turned up
first.

/dps