Dave, myself, and the MMT went to the station and retrieved the bad modem and did a cleaning.
From the email trail I believe this to have been the first visit to the CREWS station since the modem was power-cycled on October 4th or 5th.
Ross Timmerman (PacIOOS / University of Hawai`i) describes the post-retrieval evaluation of the cellular modem in a message dated Tuesday, November 15th (4:32pm Honolulu time):
I was able to connect to the modem, both with AceManager and telnet. The modem data looks good, except for the number of system resets, presently at 3953. A system reset is counted whenever the power is cycled. I'm not sure if a network outage will cause a system reset (I'm checking). Normally the number is less than 50. I've seen high number of resets when a solar battery failed to provide sufficient power. The voltage should be between 10-28V.
Given this, there are a few potential explanations: station power is too low, modem power cable was loose, faulty modem, or the modem just needed to be reset. David confirmed the station was powered when the modem was recovered, though the voltage wasn't checked. I don't think this is the cause since the voltage was looking good prior to 10/3.
Regarding the question of station power levels, I did up a graph to confirm that the reported voltages (prior to losing communications) were normal for a CREWS station. They were. I described the attached graph in an email dated Wednesday, November 16th (11:37am Miami time) in this way:I worked up a quick graph of the 6-minute voltage reports from August 23rd (day 235) to October 2nd (day 275) and it shows a normal pattern of startup charging until about September 12th, and then diurnal variations after that of about 12.5V to 14.0V (with peaks higher or lower depending on levels of sunlight each day).
Later that same day Michael Shoemaker (AOML, Miami) provided this background on the type of batteries that are installed at the CREWS station:
The batteries in the station are AGM Deep Cycle super low internal resistance mil spec. As can be seen by the graph after being in storage for most of a year on the island they started at 11.5vdc then charged to an average 12.65vdc at their lowest for night power usage. Each battery is 48Ah with a total of 96Ah total to run the station.
Ross Timmerman then suggests that David and Steven try taking the modem to Lao Lao golf course to confirm that there is cellular coverage in the immediate neighborhood of the station and that the signal strength is sufficient. In an email dated Wednesday, November 16th at 10:02am Honolulu time, he says:
The modem was left powered overnight and in checking this morning, no additional system resets were logged. I don't have records of how many resets there were prior to deployment, so it may not be an issue. The modem appears to be working fine now. Given this and the fact that the station power is also good, the next logical step is to try powering the modem from Laolao golf course to check the network and signal strength. If this proves successful, then we can plan on re-installing the modem back in the station. I think it best to rule out network or signal issues on land before scheduling the boat.