Arduino solar powered battery monitor

Projects General Guidance
1

Hey guys!

I am trying to build up a solar powered weather station with my arduino uno.
Programming is not my problem, but the hardware and the electronical skills are missing so please dont be so hard to me :slight_smile: It s only an hobby and i am very interested in these topics.

Here is my hardware list:
Solarpanel http://www.watterott.com/de/37-x-66mm-Monocrystalline-Solar-Cell
Battery Lithium Ion Battery - 2Ah - PRT-13855 - SparkFun Electronics
Arduino https://www.arduino.cc/en/Main/ArduinoBoardUno
SolarShield http://www.seeedstudio.com/depot/Solar-Charger-Shield-V2-p-914.html

My project works if i stack everything togehter, but i want to know if the battery is really charging and read the status regularly to monitor. Also i am very interested how i can measure how much power my solar panel brings. If i extend my project with other sensors, is it possible to measure how much power the arduino is consuming?

so these are my questions:

  • how can i measure my lipo battery status
  • how can i measure solar panel power
  • current power consumed by the project

I already bought a current sensor, but a member in this forum mentioned that this doesnt suits my needs:

To measure the lipo status i read a lot about voltage dividers (to limit the power to 5V), imho my project never goes over 5V and so i dont get the use of it.

http://dimitriosdesignprojects.com/projects/the-solar-energy-meter/
This project would be great, if i would find plans how to connect everything and how it works :slight_smile:

At the end i want to write a project description with all used hw, plans and everything to guide interested members.

Can u help me and guide me in the right direction?

Greetings

Danke und Gruß

2

To measure power produced or consumed, you have to measure both the voltage and current (watts = volts*amps). The voltage is easy to measure using a voltage divider and the ADC of the Arduino.

However, for low power, self contained projects like yours, it is not particularly easy to measure the current, because doing so will interfere with the current flow.

The most straightforward way is to put a resistor in the ground lead and measure the voltage drop across the resistor. Both the resistance and the voltage drop need to be very small, which means you need an amplifier to increase the voltage, so that it can be reliably measured. Not a simple thing for a beginner to design.

Your project is seriously underpowered. The solar cell (a poor choice: very expensive for such low power) is rated at 6.7V 33 mA in full sun, and this is roughly what an Arduino normally draws, so there is nothing left to charge the battery. It probably won't even run in less than full sun.

This cell is a much better deal: 4 times the power at 1/4 the price.