[amsat-bb] Re: recent AO-40 efforts?

[G0MRF@aol.com]

Hi Auke / Don
 
I believe in the case of AO-40, there is potential damage from a corrosive  
fuel 'leak'.
 
Regarding battery protection. For smaller satellites an optically  switched 
solid state relay between the battery and the satellite bus looks  to be a good 
idea.
 
Any time the battery has an EMF of greater than 2 volts the relay is  'on' 
and its MOSFETS connect the battery to the system.
 
If the battery volts go below 2V then the relay goes 'open' and the  battery 
is disconnected from the satellite allowing power from the BCR to go  directly 
to the payloads.
 
You could also send a command to switch the relay back on to recharge the  
battery at a later date.
 
Would be nice to try all this some day.  Several years of normal  operation 
followed by several years of daylight only sounds good to me.
 
Talking of daylight only....Hopefully only 6 weeks to the Delfi3c  launch!
 
73
 
David
 
 

Someone else my be able to correct my understanding if I have  misunderstood
the AO-40 design. Hopefully those who designed the power system  have moved
on and we now have some better insight.

Don



In a message dated 02/03/2008 04:06:59 GMT Standard Time,  
sparkycivic at shaw.ca writes:

I  presume that they are in a fail-close arrangement, because if they were  
fail-open, they should have already done-so due to the shunted power  system.  
Also, could the solar panels have fuses that have opened?   could such fuses 
be re-settable?

I would be interested to hear what  knowledge there exists about the present 
status of AO-40, especially what  "google" couldn't fetch.