Project Curacao2 – Flame On! Up and Running
In late October of 2017, Project Curacao2 quit charging the batteries from the Solar Panel system and then slowly died. Project Curacao2 had been down and operating solo down in the Caribbean for over 5 months.
The Repair Trip
We packed up all the materials that we thought we would need to fix our Solar Power Problem (what did we think the problem was? See this posting) as hypothesized. Then we schedule a trip down to visit the box. The visit happened about 2:30pm on Wednesday, August 1st. We took down the box and examined it.
Next, we opened up the box and started measuring voltages. The Raspberry Pi was NOT running as none of the LEDs in the box were on except a faint red one on SunControl.
The inside of the box looked really, really clean with no evidence of leaks and just a bit of dust near the vent for the box (which also feeds into the Air Quality Sensor).
Replacing the SunControl Board
Our working theory was that the solar panels charged up the battery and then went to 7.0V (the VOC (Voltage Open Circuit) of the panels we used was 7.0V and we have five of them), which then burned out the SunControl board (6.5V Max). We fixed this by adding 6.2V Zener diodes (20 1W diodes so we could take a lot of current) across the Solar Panels. No more voltages > 6.2V.
We measured the voltage of the LiPo batterie and they were about 0.69V, which is way too low for a LiPo battery so we replaced the batteries out of an abundance of caution. We took the old batteries back to the Lab and we will test them there. Next we took our pre-wired SunControl board and spliced it into the circuit.
Soldered and connected the wires for the On-Off Lighted Switch on the Box. The LED on the switch is why there are 4 wires and not just two. I like the glow.
Flame On!
After taping it up it was time for the moment of truth. We plugged in the solar panels, checked the voltages of the new batteries and the solar panels, saw that SunControl was happily starting to charge the batteries (which were almost full) and the panel voltages were sitting about 5.2V, which is a happy charging voltage (as the batteries get completely full, SunControl stops charging and the solar panel voltages start climbing toward the VOC (but not anymore because of the 6.2V Zener diodes). This was a really good sign. We reached down and pushed the On button, saw the LED on the button come on and suddenly there were lights here and there inside the box.
We couldn’t see the boot up light of the Raspberry Pi Zero underneath the Pi2Grover connector, but the lights were correctly lite up on the Pi2Grover board. We quickly ran a scan on the local network to find the PC2 Box and then logged into pi@192.168.1.3 as indicated. It worked. 
This showed that the Raspberry Pi Zero was working and was talking to the network. Note too, that the last log into this system was on Friday, October 27th in 2017, the day we lost contact with the station.
I checked the diagnostic output from the Weather Station and it was all showing nominal behavior. I was also receiving pictures now from the box via email.
As I was quickly running out of time, I reassembled the box, and walked it up the stairs to the roof and put it back in its place.
I then did some maintenance on the station house and then headed back out of town to catch our ride from Curacao.
Coming Next?
We will start getting some graphs from Project Curacao2 and lots of data. We need to reconnect the DSL modem to the PC2 address 192.168.1.3 (previously it was 192.168.1.19) to get back logging into the system and get the full flow of data running. Nothing is lost however. It’s all stored in a MySQL database, so we will work on this problem next week back in the Labs.
What is Project Curacao2?
Project Curacao2 is a redesign and rebuild of the Project Curacao environmental monitoring system that was running down on the island nation of Curacao in 2014 and 2015. We took it apart when we got down to the island and debugged the failure. It turns out what finally killed Project Curacao was the main LiPo battery on the Raspberry Pi had died. The Arduino watchdog time was happily running away, but couldn’t wake up the Raspberry Pi. We replaced the battery and the Raspberry Pi booted right up. We brought the SD Card and a variety of parts back to the Labs for analysis.
The project Project Curacao2 consists of two LoRa transmitters based on a Mini Pro LP and a Raspberry Pi Zero powered base unit. Lots and lots of sensors! All solar powered.
- Part 1 - Introduction to Project Curacao2 and the LoRa WXLink Feeder Stations
- Part 2 - First LoRa WXLink Feeder Stations Report
- Part 3 - Testing the LoRa Range
- Part 4 – Initial LoRa Range Results
- Part 5 – Final LoRa Range Results
- Part 6 - Raspberry Pi Zero Base Unit Build
- Part 7 - Flame On! Initial Base Unit Tests
- Part 8 - Solar Power Management System
- Part 9 - Ready for Deployment and Status
- Part 10 - PC2 in the Caribbean! Repairs and Testing
- Part 11 - It Lives! Deployment and Initial Results
- Part 12 - One Month of Results from Paradise
Below is a comparison shot of the original Project Curacao box (on the left) with the new Project Curacao2 box on the right. You can see from this picture the advances we have made in three years. The new Project Curacao2 box is wired together almost entirely using Grove Connectors. We have also designed and integrated new solar power controllers, wiring schemes and, in a big design decision, removed the Arduino Battery WatchDog. We found the reliability of our new solar power control scheme and power reduction techniques made the single computer Project Curacao2 possible.
