Solar Super Capacitor Power Supply

Description

Powered by the sun and requiring zero maintenance. This little board is designed to power a low power device 12/7. A Solar panel, as small as 500mW 5V (60mm X 40mm), charges the 2 x 55Farad 2.7V capacitors they in turn supplies from 0.3 to 5.5V to the TPS61200 Low Input Voltage Synchronous Boost Converter to the supply 3.3 or 5 Volts to the desired device.
The capacitors are charged in series, using a ALD910026. Protected against over voltage they are balance charged to the correct voltage and maintained as long as the sun shines. During the evening or on very cloudy days the capacitors will continue to discharge down to 0.3V where the TPS61200 will shut down. This project is a demonstration project to show how a small low power device, such as LORA can be powered without interruption indefinitely. The board is equipped with a ADS11141DGS and/or INA219 Current/Power Monitor both with I2C Interface.
Design with extremely low power consumption in mind.

Details

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)

Files

NC085PSU.kicad_pcb

Kicad PCB file Ver A

kicad_pcb - 753.59 kB - 11/09/2023 at 19:21

Download

NC085PSU.kicad_sch

Kicad Schematic file Ver A

kicad_sch - 194.00 kB - 11/09/2023 at 19:21

Download

NC085PSU-01-01b.pdf

Schematic PDF

Adobe Portable Document Format - 126.16 kB - 03/03/2022 at 01:35

Preview

NC085PSU-01-02.pdf

PCB layout PDF

Adobe Portable Document Format - 21.65 kB - 03/03/2022 at 00:55

Preview

Components

1 × ALD810026 DUAL SUPERCAPACITOR AUTO BALANCING (SAB™) MOSFET ARRAY.

1 × TPS6120A Low Input Voltage Synchronous Boost Converter With 1.3-A Switches

1 × INA21 Zerø-Drift, Bidirectional Current/Power Monitor With I2C Interface

1 × ADS1114IDGS Ultra-Small, Low-Power, I2C-Compatible, 860-SPS, 16-Bit ADCs With Internal Reference, Oscillator, and Programmable Comparator

2 × 55F 2.7v Super capacitor

Discussions

Gos wrote 01/27/2023 at 17:00

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.

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