The CREWS station at Lao Lao Bay has been online for about seven days now, so I thought I'd send a brief update on these two issues.
Regarding the modem -- I am not aware of any further modem failures since the last observed outage on Wednesday the 1st. Note that brief outages may in fact go unnoticed, since our systems automatically "catch up" our data files with all new data since the last successful connection. Extended outages (on the order of one day or more) however, would trigger alerts that would be logged, and that has not happened in the last five days.
Regarding the batteries -- please see attached graph (below) of min/max/avg station voltages per 6-minute period, plotted against day-of-year. The first night's power outage has not been repeated since, and the good news is that the station's nightly lowest-power levels have steadily increased over the past week. This is promising sign, and I believe the station could continue to operate indefinitely at these power levels.
It is true that these are not "normal" power levels for a CREWS station. Ideally I would like to see power levels range diurnally from about 12.5V to 14.5V, as (for example) we observed for this station from March to May, 2012. Right now the power levels range from about 11V to 12V. However, a look back at the station's early days in August and September of 2011 reveals a similar pattern of initial-deployment battery levels, where during its first week of life it rarely exceeded 12.5V, and in fact required a bit more than three weeks before assuming a normal 12.5V - 14.5V diurnal pattern.
So I would remain cautiously optimistic about the performance of both the modem and the batteries. Certainly there is no cause at present for immediate intervention, and I would recommend that we continue our watch-and-watch approach for at least another two weeks before making any decisions about modem troubleshooting or battery replacement.
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| Click this image for a larger version of the graph. |
Mike J+