Darryl Norman
ALD910026 DUAL SUPERCAPACITOR AUTO BALANCING (SAB™) MOSFET ARRAY.
TPS6120 Low Input Voltage Synchronous Boost Converter With 1.3-A Switches
INA219 Zerø-Drift, Bidirectional Current/Power Monitor With I2C Interface.
ADS1114IDGS Ultra-Small, Low-Power, I2C-Compatible, 860-SPS, 16-Bit ADCs With Internal Reference, Oscillator, and Programmable Comparator
J1
1 - GND
2 - VCC-Out
3 - ADD SELECT
4 - SDA
5 - SCL/Analog output
6 - RDY
7 - Solar test control
J2/SOL1
Solar Panel input
- GND
+ SOL
A similar board was used with an ATMEGS328P and an LORA RFM95W communicated every 10 minutes to The Things Stack. Without sunlight it was able to communicate for 72 hrs. The power usage graph below sowing coms burst then deep sleep. In practice it has been working in my letterbox for the last 2 years without let-up. ( see https://thingspeak.com/channels/1189753)
Jake Wachlin
Claudio Alberto Ortega
Hi Darryl,
nice project. I did something similar but a bit simpler. I use 2 supercapacitors of 5F and 5.7V in parallel. The small solar panel is connected to a boost converter to 5V connected to the supercaps. This way I always charge the supercaps at 5v, even with weak sun. Then a LDO brings the voltage of the supercaps down to 3.3v to feed an arduino pro mini (without led/voltage regulator). This way I can extract the charge of the caps from full 5V down to 2.7V when the arduino stops.
I has a temp/humitdity/press sensor and a NRF24L01 module to send the data every 15 mins. Without sun (solar panel disconnected) it runs for about 80 hours, more than 3 days! And with just a couple of minutes of sun the caps are fully charged again.
The supercaps are very cheap, 1.5€ each. I have printed a simple small PCB also.
I will create a post here when I have some time.