Solar challenge

For the Solar Challenge I created a prototype of a prototype - a data logger that records the ambient noise level (in volts) wherever it's located.

The project consists of the following elements:

• Solar panel
• LiIon battery (3.7V 2500mAh)
• LiIon/LiPoly USB charger
• Arduino Uno
• Sparkfun microSD shield
• 8GB microSD card
• Various USB adapters

I am getting upwards of 8V from the solar panel in moderate sun. The entire system seems to only be drawing around 40mA. I suspect this is because the Arduino Uno draws about 40mA and the microSD shield draws a negligible amount in comparison.

Testing the panel + battery + charger 

Close-up of microSD shield 

Panel in a bag for weather protection

Action shot - on window ledge gathering sun + data

Consolidated package using found surveillance mount

Data is written to the microSD card every 200ms - a timestamp of milliseconds since startup and a reading from the electret microphone in volts. My latest test was foiled because the microSD card got wet and stopped logging shortly after startup, but I was able to get a solid chunk of real data last week and this is presented below.