If you use 6v solar panels and set the Vin limit to 4.8v or even higher if you do not plan on plugging in any 5v USB sources then you basically force the solar cells to stay in their Vmp voltage range without needing any other circuits in the mix.
You should be using code like I’m using below to put the Electron to sleep if the battery SOC hits 20%. When the solar panels bring the SOC above 20% the Electron goes back to running it’s main loop as normal.
I have a 3w 5v solar panel + the 2300mAh battery and with the code below I can stay in deep sleep mode and wake up every hour for weeks before the battery would actually go dead.
SYSTEM_MODE(SEMI_AUTOMATIC);
//SYSTEM_THREAD(ENABLED);
// This #include statement was automatically added by the Particle IDE.
#include "Ubidots/Ubidots.h"
#define TOKEN "Token" // Put here your Ubidots TOKEN
#define DATA_SOURCE_NAME "ElectronSleepNew"
SerialLogHandler logHandler(LOG_LEVEL_ALL); //This serial prints system process via USB incase you need to debug any problems you may be having with the system.
Ubidots ubidots(TOKEN); // A data source with particle name will be created in your Ubidots account.
int button = D0; // Connect a Button to Pin D0 to Wake the Electron when in System Sleep mode.
int ledPin = D7; // LED connected to D1
int sleepInterval = 60; // This is used below for sleep times and is equal to 60 seconds of time.
ApplicationWatchdog wd(660000, System.reset); //This Watchdog code will reset the processor if the dog is not kicked every 11 mins which gives time for 2 modem reset's.
void setup() {
//Serial.begin(115200);
pinMode(button, INPUT_PULLDOWN); // Sets pin as input
pinMode(ledPin, OUTPUT); // Sets pin as output
ubidots.setDatasourceName(DATA_SOURCE_NAME); //This name will automatically show up in Ubidots the first time you post data.
PMIC pmic; //Initalize the PMIC class so you can call the Power Management functions below.
pmic.setChargeCurrent(0,0,1,0,0,0); //Set charging current to 1024mA (512 + 512 offset)
pmic.setInputVoltageLimit(4840); //Set the lowest input voltage to 4.84 volts. This keeps my 5v solar panel from operating below 4.84 volts.
}
void loop() {
FuelGauge fuel; // Initalize the Fuel Gauge so we can call the fuel gauge functions below.
if(fuel.getSoC() > 20) // If the battery SOC is above 20% then we will turn on the modem and then send the sensor data.
{
float value1 = fuel.getVCell();
float value2 = fuel.getSoC();
ubidots.add("Volts", value1); // Change for your variable name
ubidots.add("SOC", value2);
Cellular.connect(); // This command turns on the Cellular Modem and tells it to connect to the cellular network.
if (!waitFor(Cellular.ready, 600000)) { //If the cellular modem does not successfuly connect to the cellular network in 10 mins then go back to sleep via the sleep command below. After 5 mins of not successfuly connecting the modem will reset.
System.sleep(D0, RISING,sleepInterval * 2, SLEEP_NETWORK_STANDBY); //Put the Electron into Sleep Mode for 2 Mins + leave the Modem in Sleep Standby mode so when you wake up the modem is ready to send data vs a full reconnection process.
}
ubidots.sendAll(); // Send fuel gauge data to your Ubidots account.
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(250); // waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
delay(250); // waits for a second
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(250); // waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
System.sleep(D0, RISING,sleepInterval * 2, SLEEP_NETWORK_STANDBY); //Put the Electron into Sleep Mode for 2 Mins + leave the Modem in Sleep Standby mode so when you wake up the modem is ready to send data vs a full reconnection process.
}
else //If the battery SOC is below 20% then we will flash the LED 4 times so we know. Then put the device into deep sleep for 1 hour and check SOC again.
{
//The 6 lines of code below are needed to turn off the Modem before sleeping if your using SYSTEM_THREAD(ENABLED); with the current 0.6.0 firmware. It's a AT Command problem currently.
//Cellular.on();
//delay(10000);
//Cellular.command("AT+CPWROFF\r\n");
//delay(2000);
//FuelGauge().sleep();
//delay(2000);
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(150); // Waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
delay(150); // Waits for a second
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(150); // Waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
delay(150); // Waits for a second
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(150); // Waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
delay(150); // Waits for a second
digitalWrite(ledPin, HIGH); // Sets the LED on
delay(150); // Waits for a second
digitalWrite(ledPin, LOW); // Sets the LED off
System.sleep(SLEEP_MODE_DEEP, 3600); //Put the Electron into Deep Sleep for 1 Hour.
}
}