Supercapacitor lifetime: https://abracon.com/uploads/resources/Supercapacitor-Lifetime-Explained.pdf
There seem to be a lot of papers on space-qualified supercapacitors, but no off-the-shelf space-qualified ones. The temperature range is one issue out of dozens. This would hardly be the first time that the most desirable component was pure unobtanium.
On Mon, Jul 22, 2024 at 3:35 PM Starr Moffatt via AMSAT-BB < amsat-bb@amsat.org> wrote:
Batteries are often the first major things to fail. (AO7 failed then re-awoke when the battery open circuited).
I would suggest instead of having a battery, use ultra capacitors to help even out the power from the solar cells when in sunlight, and, have no transponder operation when in eclipse.
Additional advantages are: (1) ultra capacitors are lighter than a battery, (2) the solar cells need only supply the transponder, whereas there needs to be extra solar cells to also recharge the discharged battery when the bird is in sunlight.
The only disadvantage is the transponder is non operational during eclipse periods, which, in reality, is no big issue.
73 Starr ZL3CU
On 23/07/2024 5:15 am, JOHN GEIGER via AMSAT-BB wrote:
Thanks for the information on all of those things. Hopefully someday we can see some more FM satellites with this sort of lifespan!
73 John AF5CC
Sent using Zoho Mail <{0}>
---- On Mon, 22 Jul 2024 12:06:57 -0500 *Paul Stoetzer via AMSAT-BB amsat-bb@amsat.org* wrote ---
1. It's a microsat size satellite, so significantly larger than current cubesat form factors. 2. It's transmit power is just 250 mW and it transmits only while it receives a signal with a 67 Hz PL tone - there's no constant carrier or any telemetry transmissions. I'm not aware of any other payloads or signals coming from the satellite. Potentially there's not even any onboard computer drawing power. 3. Given its size, it has fairly large solar cells and likely has fairly large battery cells and given its transmit setup, the depth of discharge is likely quite low. NiCd batteries can last a real long time when the depth of discharge is kept quite low. 73, Paul, N8HM On Mon, Jul 22, 2024 at 12:05 PM JOHN GEIGER via AMSAT-BB <amsat-bb@amsat.org <mailto:amsat-bb@amsat.org>> wrote: __ SO-50 will be 22 years old in December and seems to be still be going strong, in sunlight and in eclipse. No other satellite launched since then has lived near that long. So what is SO-50s key to long life? Is it how the satellite was built? Something in its operation, like lower power on transmit? Its orbitalsetup?
Any ideas why it has lived so much longer than the recent crop of AMSATS? 73 John AF5CC Sent using Zoho Mail ----------------------------------------------------------- Sent via AMSAT-BB(a)amsat.org <http://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. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/ <https://www.amsat.org/about-amsat/> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org <https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org> To unsubscribe send an email to amsat-bb-leave(a)amsat.org <http://amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org <https://mailman.amsat.org> ----------------------------------------------------------- Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forumavailable
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Bruce Perens