Steve writes:
>
As best I recall, in 1992-93, the NiCd batteries used in what became
AO-27 and IO-26 were sourced from
>someone working with SSTL who had NiCd
matching down to a science and was able to work with relatively
>newer
cells.
This was possibly Larry Kayser, VA3LK. Larry was involved in the battery selection process for UO-11 where
he took about 250-or-so new NiCd batteries and "matched" them to pick the ones to fly on UO-11 and several
other satellites. He had a very detailed meticulous process for characterizing each battery cell to decide
which cells to put together into the battery pack on the satellite. UO-11's batteries are still working after
tens of thousands of charge/discharge cycles. Nobody else's matching process is even close to that.
Unfortunately, after much research, I still cannot find anything that Larry wrote down that describes in
detail the steps he followed to "match" the battery cells. I know he plotted many charge/discharge curves
for each cell over many different charge/discharge/temperature conditions, and even X-rayed some cells
to find other defects, but exactly what conditions he tested and exactly what he did with the charge/discharge
curves to "match" the batteries remains somewhat of a mystery.
As far as I know he never published the steps for his methods before he became a silent key. The best,
but somewhat cryptic, statement I found from him was that when selecting the cells you want the
"best matched" cells for your battey, which are not necessarily the "best" cells that you have. But how exactly
do you determine which ones are "best matched" to each other?
If anyone knows ANYTHING about his battery matching methods, please send me whatever knowledge
you have however small.
Earlier in a different thread Joe wrote:
>
What baby steps can we all take together to open up as much information as we can as soon as we can?
If you do something and it works, especially if it works well, publish your results and your methods to achieve
those results so that others can learn and build on your knowledge and experience. And, that's just a start.
It's not enough to just publish it on just your personal website, as I recently discovered when I tried to get
some not-so-old UO-11 telemetry. The author of that website had become a silent key. The website
was no longer on the web, and
archive.org had not archived the entire site!
Hard won knowledge has been lost in both cases. We need to do better.
One suggestion would be to keep a living document, updated regularly, with copies online in
multiple places, with the lessons learned and knowledge gained, and make it required reading
for each new generation of satellite builders. Contact me if you think this is a good idea, or even
if you think it's a bad idea.
73,
Douglas KA2UPW/5
"Steps down from soapbox...."