This is a good example of why open source development is so important, especially for a small volunteer organization. A large, complex problem like developing a satellite is a difficult task for a small group of volunteers working countless hours. When the project can be reviewed by dozens of eyes all over the world more progress can be made in less time. We are about to launch a satellite that will most likely have the same issue unfortunately.
Howie AB2S
From: Burns Fishermailto:[email protected] Sent: Tuesday, December 8, 2020 9:01 AM To: Yono Adisoemartamailto:[email protected] Cc: AMSAT BBmailto:[email protected] Subject: [AMSAT-BB] Re: How to determine why Fox satellite batteries failed before projected 5 year lifetime
Thanks for the info, Yono. That is a very good idea; unfortunately the satellite does not have that kind of command capability. We have learned a lot from the Fox program!
73,
Burns WB1FJ
On Mon, Dec 7, 2020 at 11:58 PM Yono Adisoemarta <[email protected]mailto:[email protected]> wrote:
Dear all,
This morning I plot the Cell A of the past week and I see three different battery discharge slope during evening pass over Jakarta (around 14:00 - 16:30 UTC)
The leftmost blue line in gray background shows normal discharge during evening pass, followed by slightly steeper decline that tripped the satellite into Safe mode just before TCA over me in Jakarta. The rightmost decline was from last night (16:23 UTC 7 Dec pass) that shows an even steeper decline. This is very discouraging in my opinion.
So, to prevent further deterioration of this cell, would it be possible to command “put into Safe Mode if in Eclipsed” ?
Use the sun sensor to determine sunlight.
73 de Yono - YD0NXX Jakarta, Indonesia - OI33JR
Sent from my iPhone
On Dec 8, 2020, at 11:33 AM, John Brier <[email protected]mailto:[email protected]> wrote:
Thank you very much Paul.
I must have missed that during the Symposium.
So overall, do you think the time the satellites were in eclipse and in use was longer than expected?
Otherwise what would explain the higher than planned depth of discharge?
73, John Brier KG4AKV
P.S.
For anyone else looking through the PDF mentioned earlier, the cells mentioned on page 324 were 6x SANYO KR1700AU "A" CELLS, which apparently didn't end up being the actual used cells, as Paul mentioned
On Mon, Dec 7, 2020 at 2:59 PM Paul Stoetzer <[email protected]mailto:[email protected]> wrote:
Each Fox-1 satellite uses 6 Sanyo KR-1400AE NiCd A cells.
Obviously we all hoped that the batteries would last a lot longer. As discussed during the Symposium, the likely cause of battery failure is a higher than planned depth of discharge. Note that AO-92's batteries failed more quickly than AO-91. Since AO-92's evening passes were generally between 9 and 11 pm, AO-92 saw lots of use while in ecilpse. Contrast that to AO-91, where the evening passes were generally after midnight, so it saw less use while in eclipse.
I'm not sure there's much to be learned from the experience with these batteries as NiCd battery technology is now certainly obsolete and will not be used in future AMSAT satellites. AMSAT's GOLF series of satellites will use lithium ion batteries. More information about the progress of GOLF, including the GOLF-TEE status paper from the 2020 Symposium Proceedings, can be found at https://www.amsat.org/greater-orbit-larger-footprint-an-introduction-to-the-...
73,
Paul, N8HM
AMSAT-BB mailing list -- [email protected]mailto:[email protected] View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/[email protected] To unsubscribe send an email to [email protected]mailto:[email protected] Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
----------------------------------------------- AMSAT-BB mailing list -- [email protected]mailto:[email protected] View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/[email protected] To unsubscribe send an email to [email protected]mailto:[email protected] Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org