[amsat-bb] Re: Can we get them to fix AO-40 first then?

Peter Guelzow peter.guelzow at kourou.de
Sat Oct 17 12:30:27 PDT 2009

Hi Gordon,

such a fuse would not prevent a battery from an internal short-cut in
one or more cells...  that's in fact what happened to AO-40.
Also you have to make such a "failsafe" feature really fail safe, so
that it does not hit you in the back if it fails..
These kind of things, like Watchdogs, always sound simple and easy, but
very often they are cause for more trouble.
We have seen satellites with Watchdogs going mad and resetting computers
while it was not necessary and do more harm than good.
Clearly, nobody expected that the battery would die so quickly,
otherwise some actions would have been done before...

73s Peter

Gordon JC Pearce wrote:
> On Mon, 2009-10-12 at 03:24 -0400, Luc Leblanc wrote:
>> 40 back, we will. If the voltage is clamped low and there is no other damage, we may end up waiting a long time for a cell to "open", 
>> hopefully not as long as for AO-07. ..or it may happen today. No success for even weeks or months does not mean that we won't eventually be 
>> successful. 
> On a more practical note, could there be some sort of failsafe "battery
> went phut so disconnect it" device?  I'm guessing a perfectly ordinary
> inline fuse would be too simple, but perhaps some sort of mechanical
> latch that would just pop the battery terminal if it lost power would
> work.
> Gordon MM0YEQ
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