diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index e76a117..3a1a0af 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -106,6 +106,14 @@ void setup() {
 
   digitalWrite(STATUS_LED_PIN, LOW);
 
+  if (currentSensorData[SENSOR_BAT_VOLTAGE] <= 3.4)
+  {
+#ifdef DEBUG
+    Serial.println("Low battery, going into deep sleep.");
+#endif
+    ESP.deepSleep(4294967295); // battery low, shutting down
+  }
+
   WiFi.mode(WIFI_OFF);
   WiFi.forceSleepBegin();