📶 WiFi Power Optimization - Minimizing Connection Time

WiFi consumes 100-170mA while connected - this is the #1 battery killer in IoT sensors! A standard 2600mAh battery would last only 1-2 days with constant WiFi. But with proper optimization, the same battery can last 2-3 months!

📊 Bad vs Good Practice

// ❌ BAD: Keep WiFi connected constantly (170mA always)
void badExample() {
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) delay(100);
    sendData();
    // WiFi stays ON after sending - battery dies in 1-2 days!
}

// ✅ GOOD: Connect only when needed, disconnect immediately
void goodExample() {
    WiFi.begin(ssid, password);
    int attempts = 0;
    while (WiFi.status() != WL_CONNECTED && attempts < 20) {
        delay(200);
        attempts++;
    }
    if (WiFi.status() == WL_CONNECTED) {
        sendData();                    // Send batch of data
        WiFi.disconnect(true);         // Power down WiFi radio
        WiFi.mode(WIFI_OFF);           // Turn off completely
    }
}
    

📖 Complete Optimized WiFi Code

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "YOUR_WIFI";
const char* password = "YOUR_PASSWORD";
const char* token = "YOUR_OCEANREMOTE_TOKEN";

// Static IP for faster connection (saves 1-2 seconds!)
IPAddress staticIP(192,168,1,100);
IPAddress gateway(192,168,1,1);
IPAddress subnet(255,255,255,0);
IPAddress dns(8,8,8,8);

void connectFast() {
    // Configure WiFi for minimum connection time
    WiFi.mode(WIFI_STA);
    WiFi.setSleep(true);                    // Enable modem sleep
    WiFi.setAutoConnect(false);             // Don't scan for networks
    WiFi.config(staticIP, gateway, subnet, dns);  // Static IP = faster!
    
    WiFi.begin(ssid, password);
    
    // Timeout after 5 seconds max
    unsigned long start = millis();
    while (WiFi.status() != WL_CONNECTED && 
           millis() - start < 5000) {
        delay(50);
    }
}

void sendData() {
    if (WiFi.status() != WL_CONNECTED) return;
    
    HTTPClient http;
    http.begin("https://api.oceanremote.net/device/state");
    http.addHeader("Content-Type", "application/x-www-form-urlencoded");
    
    // Batch multiple readings in one request
    String data = "token=" + String(token);
    data += "&soil_moisture=" + String(readSoilMoisture());
    data += "&temperature=" + String(readTemp());
    data += "&battery=" + String(readBattery());
    
    http.POST(data);
    http.end();
}

void setup() {
    Serial.begin(115200);
    
    connectFast();           // Connect (1-3 seconds)
    
    if (WiFi.status() == WL_CONNECTED) {
        sendData();          // Send data (under 1 second)
        WiFi.disconnect(true);   // Disconnect WiFi
        WiFi.mode(WIFI_OFF);     // Turn off radio completely
    }
    
    // Go to deep sleep for 1 hour
    esp_sleep_enable_timer_wakeup(3600000000);
    esp_deep_sleep_start();
}

void loop() {
    // Empty - everything runs in setup()
}
    

📊 Power Savings Comparison