[amsat-bb] AO-92

[Chris Thompson]

Bill,

It's true that we think AO-85's battery was damaged due to overheating, but
it is just a theory based on the telemetry that was downlinked.  Now that
we have two cases where the batteries have failed we might be able to see a
different pattern.  With that said AO-85 had a linear power supply and
AO-92 had an MPPT, so the hardware is not identical as I remember.  I think
AO-91 and AO-92 are almost exactly the same except for experiments
onboard.

If it's something you (or others) want to research then you can pull down
the telemetry with FoxTelem or I can supply you with an extract and
explanations.  All of the schematics are available in the symposium
proceedings from previous years.

73
Chris

On Mon, Sep 14, 2020 at 7:48 PM Bill Gaylord via AMSAT-BB <
amsat-bb at amsat.org> wrote:

> Didnt AO-85 cells fail due to over heating? Maybe the cell dying on AO-92
> was just weaker then the others.
>
> Or maybe the L/U mode strained them more? As that was a key difference
> between AO-85 and AO-92. Does AO-91 have L/U i dont recall if it did.
>
> KD9kCK
>
>
> On Mon, Sep 14, 2020, 6:07 PM Andrew Glasbrenner <
> glasbrenner at mindspring.com>
> wrote:
>
> > A few factors probably involved:
> >
> > AO-85 saw less use due to being a little harder to access. It was also in
> > a higher orbit, that wasn’t sun-synchronous with a near 12 o’clock LTAN,
> so
> > it saw more sunlight.
> >
> >
> >
> > 73, Drew KO4MA
> >
> >
> >
> > *From:* Bill Gaylord <chibill110 at gmail.com>
> > *Sent:* Monday, September 14, 2020 6:31 PM
> > *To:* Andrew Glasbrenner <glasbrenner at mindspring.com>
> > *Cc:* Roy Dean <royldean at gmail.com>; AMSAT BB <amsat-bb at amsat.org>
> > *Subject:* Re: [amsat-bb] AO-92
> >
> >
> >
> > Just wondering why AO-92 is failing so much quicker than AO-85. AO-85
> > lasted about 4 years in space till it went silent / started having
> battery
> > issues. AO-92 has only been in space for about 2 and 3/4 years.
> >
> >
> >
> >
> >
> >
> >
> > AO-91 seems to be doing okay. Or at least I haven't seen anyone talking
> > about it going into safemode. And I haven't heard it in safemode.
> >
> >
> >
> > 73
> >
> > William KD9KCK
> >
> >
> >
> >
> >
> > On Mon, Sep 14, 2020 at 5:14 PM Andrew Glasbrenner via AMSAT-BB <
> > amsat-bb at amsat.org> wrote:
> >
> > I've mostly been posting about it on Twitter.
> >
> > AO-92 has a cell that's failing, and towards the end of many eclipses it
> > goes into auto-safe mode at 3.6v. If the battery drops low enough the IHU
> > resets, and it comes back up in normal safe mode. Mark and I have been
> > commanding to repeater mode on the first available pass after the resets,
> > but it's not a long term sustainable answer. Last night Mark commanded
> the
> > transmitter completely off while we consider a plan of action.
> >
> > Leaving autosafe on and the tx off, we may be able to turn the repeater
> on
> > ad-hoc for weekends or such, completely dependent on command station
> > availability. Turning autosafe and the IHU off like we did with AO-85
> will
> > kill the satellite pretty quickly, so that's not a good response either.
> > So,
> > we'll look at resets and battery states before this weekend and see where
> > we
> > stand.
> >
> > 73, Drew KO4MA
> > AMSAT VP Operations
> >
> > -----Original Message-----
> > From: AMSAT-BB <amsat-bb-bounces at amsat.org> On Behalf Of Roy Dean via
> > AMSAT-BB
> > Sent: Monday, September 14, 2020 4:55 PM
> > To: amsat-bb at amsat.org
> > Subject: [amsat-bb] AO-92
> >
> > I can find no information about AO-92 going silent recently.   Was it
> > commanded into a silent state (as AO-85 was shortly before it went silent
> > permanently)?
> >
> > --Roy
> > K3RLD
> > _______________________________________________
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> >
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> > to all interested persons worldwide without requiring membership.
> Opinions
> > expressed
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> >
> >
> _______________________________________________
> Sent via AMSAT-BB at 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!
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>


-- 
Chris E. Thompson
chrisethompson at gmail.com
g0kla at arrl.net