[amsat-bb:74843] Re: AO-40 mystery effect?

[Peter Guelzow <peter.guelzow@xxxxxxxxx>]

Hi All,

just a small correction..

> the "mystery effect" is working in our favor at this time and should do so  
> for several months.
> Currently it is getting AO-40 into a better sun angle which will, we hope,  
> enable Auxiliary battery charging.

The better sun angle alone will not help us to get the Auxiliary battery
charging...

The problem is, that the Main Battery clamps the bus voltage down to
about 14V or even less, from its nominal 24V.

As Stacey described, this is obviously due to several battery cells in
the main battery, which failed shortened in some sort of domino effect.

It happened so fast, that we were not able to completely isolate the main
battery and use only the aux battery.  At the moment both batteries are
in parallel.. this will not damage the AUX battery, but it prevents it
from charging.

The extremely low battery (and bus) voltage is a problem, because the
transmitters and other electronics were not designed or may not work
at these low voltages..

The IHU and receivers should still work, but without telemetry it
is hard to predict what the current situation really is..

Since the solar panels pump all their energy into the remaining cells
of the main battery, they will indeed get very hot..  Our hope now
is (and that's what is to be expected) that these cells will vent
all their electrolyte and dry out. When that happens, the cells should
fail "high resistance" and our bus voltage should come up..

Thus, the improving sun angle should help in speeding up this process.
But again, we yet do not know how long this will take.. but chances
not bad for this to happen..

73s Peter, DB2OS
Pres. AMSAT-DL


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