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Re: Re:Re: Re: The hard questions..

----- Original Message ----- 
From: "Stacey E. Mills" <w4sm@AMSAT.Org>
To: "Amsat Bulletin Board" <amsat-bb@AMSAT.Org>
Sent: Monday, February 16, 2004 5:16 AM
Subject: [amsat-bb] Re:Re: Re: The hard questions..

> >In hindsight at the time of failure,cutting both batteries open might
> >been yet another option, since you could then catch the sat in sunlight
> >look at what was going on with both batts before committing to one or the
> >other... but there may be things I'm not aware of that would have
> >this from working...
> That command is not an option.  The hardware prevents taking both
> off-line.
As we learned from AO-7 the batteries can fail and short out the buss. We
had to wait 20 years for the batteries to open. We need to design the next
bird to assume this will happen.

I would think the correct design would be to automatically disconnect all
batteries in an extreme low voltage situation. The satellite could then be
run on solar while the batteries are charged via high resistance path and
then connected to the buss if they charge. If a bad set is connected they
will be automatically dropped and another set can be connected if available.
We know the eventually every satellite will be running on solar alone,
without batteries. We need to design for this at the beginning.

If this has already been suggested please excuse my oversight.


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