- 287: power, Site , Mon 14-Aug-2006 11:32:07 MST, Vbatt spikes
We've known for a while that the small downward spikes on Vbatt are associated
with TP01 sampling. They happen every 3 hours only at the flux sites. They
are in the raw_data files. I think this is simply the real drop caused by
consuming power when heating the soil. I think we put about 1V into a 15ohm
resistor of the probe, which would be 1/15 A. I think the 10V regulator would
see this current, so the power would be 10/15W. At the power voltage of 13V,
this would be 0.05A. If the cable resistence was 0.2 ohm, the resultant
additional voltage drop would be 0.01 V. We see about 0.04 V usually, so
maybe the cable resistence is higher (0.8 ohm?).
I also note that the voltage drop at site 10 is larger. This site uses a
grey PVC cable which might have higher resistence than our normal green
cables (and also may be longer?).
Thus, I'm reasonably satisfied that this is a real drop in power and is not
a concern.
- 242: power, Site 10, Tue 08-Aug-2006 15:10:47 MST, Station visit, site 10, Aug 8
Visited site, giving a tour for Susanne Grossman-Clarke of ASU.
While lifting charge controller out of battery box to inspect,
the load circuit connector was bent up, almost breaking its
connections to the board. Shut down power and pushed connector
back down on the board. Station is operating, but this
controller board should be replaced and inspected.
- 35: power, Site 5, Tue 04-Jul-2006 21:41:24 MDT, Site 5 power issue/shading
At Site 5 the solar panels are in shade in the morning (~730am - 10 am) in their west-of-tower location. This appears to be responsible for the steadily lowering battery voltage with time (in addition to operating the LiCor there). This is particularly difficult because in the afternoon solar radiation is often obscured by monsoon rain and cloud. We will move the system to the northeast of the tower tomorrow or the following day.