diff --git a/variants/rak3112/RAK3112Board.h b/variants/rak3112/RAK3112Board.h
index 8ba3197cf6c..8045ee06501 100644
--- a/variants/rak3112/RAK3112Board.h
+++ b/variants/rak3112/RAK3112Board.h
@@ -6,22 +6,17 @@
 
 // built-ins
 #ifndef PIN_VBAT_READ
-  #define  PIN_VBAT_READ    1
+  #define  PIN_VBAT_READ    1     // WB_A0, VBAT via the WisBlock base board divider
 #endif
-#ifndef PIN_ADC_CTRL
-  #define  PIN_ADC_CTRL         36
-#endif
-#define  PIN_ADC_CTRL_ACTIVE    LOW
-#define  PIN_ADC_CTRL_INACTIVE  HIGH
-#define  ADC_MULTIPLIER   (3 * 1.73 * 1.187 * 1000)
+// WisBlock base boards (RAK19007 etc.) divide VBAT with 1M / 1.5M (nominal x1.667); 1.73 compensates
+// for ADC loading of the high-impedance divider (same empirical value as Meshtastic's RAK4631)
+#define  ADC_MULTIPLIER   1.73f
 #define  BATTERY_SAMPLES 8
+// NOTE: no ADC enable pin on the RAK3112. GPIO33-37 belong to the octal PSRAM and must not be touched.
 
 #include <driver/rtc_io.h>
 
 class RAK3112Board : public ESP32Board {
-private:
-  bool adc_active_state;
-
 public:
   RefCountedDigitalPin periph_power;
 
@@ -30,13 +25,6 @@ class RAK3112Board : public ESP32Board {
   void begin() {
     ESP32Board::begin();
 
-    // Auto-detect correct ADC_CTRL pin polarity (different for boards >3.2)
-    pinMode(PIN_ADC_CTRL, INPUT);
-    adc_active_state = !digitalRead(PIN_ADC_CTRL);
-
-    pinMode(PIN_ADC_CTRL, OUTPUT);
-    digitalWrite(PIN_ADC_CTRL, !adc_active_state); // Initially inactive
-
     periph_power.begin();
 
     esp_reset_reason_t reason = esp_reset_reason();
@@ -81,13 +69,14 @@ class RAK3112Board : public ESP32Board {
   uint16_t getBattMilliVolts() override {
     analogReadResolution(12);
 
-    uint32_t raw = 0;
+    // analogReadMilliVolts() applies the eFuse ADC calibration
+    uint32_t mv = 0;
     for (int i = 0; i < BATTERY_SAMPLES; i++) {
-      raw += analogRead(PIN_VBAT_READ);
+      mv += analogReadMilliVolts(PIN_VBAT_READ);
     }
-    raw = raw / BATTERY_SAMPLES;
+    mv = mv / BATTERY_SAMPLES;
 
-    return (ADC_MULTIPLIER * raw) / 4096;
+    return (uint16_t)(ADC_MULTIPLIER * mv);
   }
 
   const char* getManufacturerName() const override {
diff --git a/variants/rak3112/platformio.ini b/variants/rak3112/platformio.ini
index a7d27a65b77..15ea863716b 100644
--- a/variants/rak3112/platformio.ini
+++ b/variants/rak3112/platformio.ini
@@ -1,6 +1,8 @@
 [rak3112]
 extends = esp32_base
 board = esp32-s3-devkitc-1
+; RAK3112 (ESP32-S3R8) has 8MB octal PSRAM; the devkitc-1 default (qio_qspi) fails to detect it
+board_build.arduino.memory_type = qio_opi
 build_flags =
   ${esp32_base.build_flags}
   ${sensor_base.build_flags}
@@ -35,6 +37,9 @@ build_flags =
 build_src_filter = ${esp32_base.build_src_filter}
   +<../variants/rak3112>
   +<helpers/sensors>
+; MQTT helpers need the MQTT-only libs (Timezone, ArduinoJson); the *_observer_mqtt envs add them back
+  -<helpers/MQTTMessageBuilder.cpp>
+  -<helpers/JWTHelper.cpp>
 lib_deps =
   ${esp32_base.lib_deps}
   ${sensor_base.lib_deps}
@@ -273,12 +278,10 @@ lib_deps =
 extends = rak3112
 build_flags =
   ${rak3112.build_flags}
-  -D ADVERT_NAME='"RAK3112 v3 Sensor"'
+  -D ADVERT_NAME='"RAK3112 Sensor"'
   -D ADVERT_LAT=0.0
   -D ADVERT_LON=0.0
   -D ADMIN_PASSWORD='"password"'
-  -D ENV_PIN_SDA=33
-  -D ENV_PIN_SCL=34
 ;  -D MESH_PACKET_LOGGING=1
 ;  -D MESH_DEBUG=1
 build_src_filter = ${rak3112.build_src_filter}