Project Curacao has now been down in the Caribbean for two weeks now. We’ve had some issues but they have been resolved. We are writing an article for MagPi magazine describing all of our issues with the box and the wind turbine. Major points are:
1) Minor problems with the box and shipment. Loose grounds, unplugged sensors (looks like the TSA picked up the box by the outside temperature sensor). No problem at all with the TSA. We put in a letter in the box describing the project and copies of articles we had written and it went through with no problems.
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| Pre-installation Checkout |
2) The special hardware to mount the box to the tower did not fit. We had to strap it to the tower and orient the solar panels perpendicular to the ground.
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| Mounting Platform |
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| Installation |
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| Installed Project Curacao |
3) Lower solar power than design. The strapping on the side of the tower would work in Idaho (45 degrees latitude) but gives very little power in Curacao (12 degrees latitude). The problem with this was not with the Raspberry Pi. It was with the Battery Watchdog Arduino. We adjusted the run time of the Pi with the Arduino to fit the available power. However, the Arduino is meant to run 100% of the time and the behavior of the Arduino is ill-defined in very low battery conditions. It would glitch the real time clock which gave some very random behavior.
We fixed this by moving the box down off the tower and onto the roof until we get a new mounting platform.
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| Arduino Control Screen |
Note on the RasPiConnect (www.milocreek.com) screen above you can see the Arduino battery voltage going down and down and down until we turned it off for a few days and moved it to the roof.
Here is a picture from the box’s new location (again from RasPiConnect):
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| Camera Subsystem Control Screen |
Here is a picture of the box in it’s new happy place.
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| Relaxing in the Caribbean – but with Power |
4) The wind turbine worked as predicted by our models. We switched on the turbine at night to provide a trickle charge to the main computer. We got about 60 – 90ma of current at 15MPH. No where close to the 200-300ma it takes to run the Pi. However, a wind storm came through and destroyed the turbine about a week after installation. Note that the turbine popped out of the stand and throughly destroyed itself. We think that is was a sympathetic vibration with a particular wind speed (much like the “Galloping Gertie” Tacoma Narrows bridge) since we observed that the stand was flexing in the wind. We will either prevent the next turbine from popping out or stiffen the stand to prevent the flexing or possibly both.
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| Destroyed Wind Turbine |
We plan to replace the turbine and get a new mounting platform for our September 2014 maintenance trip to Curacao.
