From Amsat-BB:


The AO-40 command team has established a routine of trying to cycle the
main battery off (aux. battery on) and then the S2 Tx ON every orbit,
using simple machine codes. Following this, the sequence to disconnect
all transmitters is sent, to protect them from low voltage. If we have
approximately 10 volts on the main buss, then these commands should be
making it through, but the S2 transmitter was not designed to run below
20 volts and is not coming on. The battery relay has been tested in the
amsat lab, where a duplicate exists, and it will cycle reliably at 12
volts, but not lower. If we have less than 10 volts, then the commands
will not be received because the IHU-1 and/or command receivers are
insufficiently powered. Either way, the IHU-1 is not currently running
IPS. The machine code commands only function in reset mode. We assume
that we currently have less than 12 volts and that either the IHU-1 and
relay are not functional (10 volts) or the relay isn't functional (12
volts), because cycling the relay should get us out of this situation by
disconnecting the main battery.

With regard to the stability of the attitude/spin, this will not be a
concern for a very long time. We are currently rotating at 3.5 RPM. The
spin decay rate is extremely slow. It will take approximately 4 years to
drop this to 3.0 RPM. We can magnetorque at speeds as low as 1.5 RPM.
The mystery effect will decrease ALON approximately 11.5 degrees/week.
It does not affect ALAT, though ALAT will change slightly as the orbit
precesses.

MAIN BATTERY NOTES (and conjecture):
The main batteries consist of three packs housed in sheet aluminum cases
and bolted to the radial braces between panels 1/6, 2/3 and 4/5. The
cells within the packs have threaded metal binding posts and the cells
are connected by thick metal straps with strain relief "U's" in them.
The pack at 2/3 consists of 7 cells and is the negative end of the chain.
The pack at 1/6 consists of 6 cells and is in the middle of the chain.
The pack at 4/5 consists of 7 cells and is at the positive end of the
chain. The main battery pack at 1/6 is the closest battery to the
"flaky" heat pipe thermistor, though it is located "below" this heat pipe
near the omni end of the spacecraft. Main battery packs 4/5 and 1/6 lost
their thermistors during the 400N incident. Whether this was due to
trauma to the battery or damage to the cabling is unknown. If a short to
ground occurred in the 1/6 battery pack it would pull the cells on the
negative side of the short in this pack to zero, as well as all cells in
the 2/3 pack. Depending on the location of the short and the status of
the cells in pack 4/5, this could pull the main buss voltage to half
normal (14 volts) or even 10 volts or below. conjecture A short at this
location might have generated enough localized heat (or even some hot
metal spatter) to damage the thermistor on the flaky heatpipe or, more
likely, its wiring. This is appealing because it would represent a
single point failure, rather than a failure cascade. One piece of
evidence that doesn't clearly fit with this theory is that the cells in
pack 2/3, the one main battery pack that still has a thermistor
temperature sensor, do not appear to get warm following the voltage drop.
We do not know how much capacity remained in these cells. It is possible
they contained relatively little energy. /conjecture

As several of you indicated, we are in a waiting game for the main
battery to develop one "open" cell.

--W4SM for the AO-40 Command Team