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
On Fri, Mar 13, 2020 at 5:58 PM Pedro Converso via AMSAT-BB < [email protected]> wrote:
LO-19 (aka LUSAT) after 30 years in space is emitting day and night a strong carrier.
What is amazing that after over 2 millions charge/discharge cycles its vintage NI-CD batteries are still able to receive and hold charge.
It is known that Lithium based batteries usually halve charge capacity after +/- 400 cycles, probably you noticed that on your portable device. https://batteryuniversity.com/_img/content/lithium2.jpg
This is just a comment for future satellite plans if long duration is part of the objective.
73, lu7abf, Pedro _______________________________________________ Sent via [email protected]. 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