This is a good catch Mike. I'm saving it to provide to the uni's I work with.
Jim
On 3/15/2020 9:47 PM, Mike Wilhelm via AMSAT-BB wrote:
Stumbled on this paper by accident:
http://adsabs.harvard.edu/full/1998ESASP.416..715C
-Mike
On Sat, Mar 14, 2020, 10:02 PM Jerry Buxton via AMSAT-BB amsat-bb@amsat.org wrote:
Amen.
Jerry Buxton, NØJY
On 3/14/2020 11:53, Robert Bruninga via AMSAT-BB wrote:
We have used NiCds on all of my 4 satellites with no battery problems.
They are robust, and survive all student mistakes and require no Battery management system when paired with a matching solar panel design. IE, as th batteries approach full charge is the same point where the solar panel voltage maxes. Also NiCd's can be safely overcharged at 10% indefinitely with no concern. (you only get an hour in the sun and then 35 minutes eclipse)...
Yes, they are twice as heavy as Lithium, but the advantages FAR outweigh the criticality of Lithium concerns and complexity of the BMS and total failure on overcharge or undercharge.
And MASS is an advantage! PSAT and BRICSAT-1 are identical 1.5U
cubesats
launched at the same time in May 2015. But PSAT with big C cell NiCd's
was
made heavier with lead ballast to 2.3kg. BRICSAT (1.7 kg) with
lightweight
Lithiums has already decayed in November. PSAT is predicted to last 2
more
years! Same thing for identical RAFT and MARSCOM cubesats back in 2006. RAFT was ballasted up and lasted TWICE as long as MARSCOM.
For comm satellites, there is no reason to come in under mass. Always ballast up to the maximum the launcher will allow!
Bob, WB4APR
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Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb