diff --git a/Software/src/communication/precharge_control/precharge_control.cpp b/Software/src/communication/precharge_control/precharge_control.cpp
index f2942afc..0de3c55b 100644
--- a/Software/src/communication/precharge_control/precharge_control.cpp
+++ b/Software/src/communication/precharge_control/precharge_control.cpp
@@ -12,8 +12,24 @@
 #define Precharge_default_PWM_Freq 11000
 #define Precharge_min_PWM_Freq 5000
 #define Precharge_max_PWM_Freq 34000
-#define PWM_Res 8
+#define Precharge_PWM_Res 8
+
+#define PWM_Freq 20000  // 20 kHz frequency, beyond audible range
+#define PWM_Res 10      // 10 Bit resolution 0 to 1023, maps 'nicely' to 0% 100%
+#define PWM_HOLD_DUTY 250
 #define PWM_OFF_DUTY 0
+#define PWM_ON_DUTY 1023
+
+#define ON 0  //Normally closed contactors use inverted logic
+#define OFF 1 //Normally closed contactors use inverted logic
+
+#ifdef INVERTER_DISCONNECT_CONTACTOR_IS_NO  
+#undef ON
+#define ON 1
+#undef OFF
+#define OFF 0
+#endif  //INVERTER_DISCONNECT_CONTACTOR_IS_NO
+
 
 #define PWM_Precharge_Channel 0
 unsigned long prechargeStartTime = 0;
@@ -28,10 +44,10 @@ void init_precharge_control() {
 #ifdef DEBUG_LOG
   logging.printf("Precharge control initialised\n");
 #endif
-  pinMode(PRECHARGE_PIN, OUTPUT);
-  digitalWrite(PRECHARGE_PIN, LOW);
-  pinMode(POSITIVE_CONTACTOR_PIN, OUTPUT);
-  digitalWrite(POSITIVE_CONTACTOR_PIN, LOW);
+  pinMode(HIA4V1_PIN, OUTPUT);
+  digitalWrite(HIA4V1_PIN, LOW);
+  pinMode(INVERTER_DISCONNECT_CONTACTOR_PIN, OUTPUT);
+  digitalWrite(INVERTER_DISCONNECT_CONTACTOR_PIN, ON);
 }
 
 // Main functions
@@ -46,33 +62,24 @@ void handle_precharge_control() {
 #endif
 #endif
 
-  // Handle actual state machine. This first turns on Negative, then Precharge, then Positive, and finally turns OFF precharge
   switch (datalayer.system.status.precharge_status) {
     case AUTO_PRECHARGE_IDLE:
 
-#if 0
-      if (datalayer.battery.status.bms_status != FAULT && datalayer.battery.status.real_bms_status == BMS_STANDBY &&
-          /*datalayer.system.status.inverter_allows_contactor_closing &&*/
-          !datalayer.system.settings.equipment_stop_active) {
-        datalayer.system.status.precharge_status = AUTO_PRECHARGE_START;
-      }
-#else
       if (datalayer.system.settings.start_precharging) {
         datalayer.system.status.precharge_status = AUTO_PRECHARGE_START;
       }
-#endif
       break;
 
     case AUTO_PRECHARGE_START:
       freq = Precharge_default_PWM_Freq;
-      ledcAttachChannel(PRECHARGE_PIN, freq, PWM_Res, PWM_Precharge_Channel);
-      ledcWriteTone(PRECHARGE_PIN, freq);  // Set frequency and set dutycycle to 50%
+      ledcAttachChannel(HIA4V1_PIN, freq, Precharge_PWM_Res, PWM_Precharge_Channel);
+      ledcWriteTone(HIA4V1_PIN, freq);  // Set frequency and set dutycycle to 50%
       prechargeStartTime = currentTime;
       datalayer.system.status.precharge_status = AUTO_PRECHARGE_PRECHARGING;
 #ifdef DEBUG_LOG
       logging.printf("Precharge: Starting sequence\n");
 #endif
-      digitalWrite(POSITIVE_CONTACTOR_PIN, HIGH);
+      digitalWrite(INVERTER_DISCONNECT_CONTACTOR_PIN, OFF);
 
       break;
 
@@ -103,24 +110,24 @@ void handle_precharge_control() {
         logging.printf("Precharge: Target: %d V  Extern: %d V  New frequency: %u Hz\n", target_voltage / 10,
                        external_voltage / 10, freq);
 #endif
-        ledcWriteTone(PRECHARGE_PIN, freq);
+        ledcWriteTone(HIA4V1_PIN, freq);
       }
 
       if ((datalayer.battery.status.real_bms_status != BMS_STANDBY &&
            datalayer.battery.status.real_bms_status != BMS_ACTIVE) ||
           datalayer.battery.status.bms_status != ACTIVE || datalayer.system.settings.equipment_stop_active) {
-        pinMode(PRECHARGE_PIN, OUTPUT);
-        digitalWrite(PRECHARGE_PIN, LOW);
-        digitalWrite(POSITIVE_CONTACTOR_PIN, LOW);
+        pinMode(HIA4V1_PIN, OUTPUT);
+        digitalWrite(HIA4V1_PIN, LOW);
+        digitalWrite(INVERTER_DISCONNECT_CONTACTOR_PIN, ON);
         datalayer.system.status.precharge_status = AUTO_PRECHARGE_IDLE;
 #ifdef DEBUG_LOG
         logging.printf("Precharge: Disabling Precharge bms not standby/active or equipment stop\n");
 #endif
       } else if (currentTime - prechargeStartTime >= MAX_PRECHARGE_TIME_MS ||
                  datalayer.battery.status.real_bms_status == BMS_FAULT) {
-        pinMode(PRECHARGE_PIN, OUTPUT);
-        digitalWrite(PRECHARGE_PIN, LOW);
-        digitalWrite(POSITIVE_CONTACTOR_PIN, LOW);
+        pinMode(HIA4V1_PIN, OUTPUT);
+        digitalWrite(HIA4V1_PIN, LOW);
+        digitalWrite(INVERTER_DISCONNECT_CONTACTOR_PIN, ON);
         datalayer.system.status.precharge_status = AUTO_PRECHARGE_OFF;
 #ifdef DEBUG_LOG
         logging.printf("Precharge: Disabled (timeout reached / BMS fault) -> AUTO_PRECHARGE_OFF\n");
@@ -129,9 +136,9 @@ void handle_precharge_control() {
 
         // Add event
       } else if (datalayer.system.status.battery_allows_contactor_closing) {
-        pinMode(PRECHARGE_PIN, OUTPUT);
-        digitalWrite(PRECHARGE_PIN, LOW);
-        digitalWrite(POSITIVE_CONTACTOR_PIN, LOW);
+        pinMode(HIA4V1_PIN, OUTPUT);
+        digitalWrite(HIA4V1_PIN, LOW);
+        digitalWrite(INVERTER_DISCONNECT_CONTACTOR_PIN, ON);
         datalayer.system.status.precharge_status = AUTO_PRECHARGE_COMPLETED;
 #ifdef DEBUG_LOG
         logging.printf("Precharge: Disabled (contacts closed) -> COMPLETED\n");
@@ -153,8 +160,8 @@ void handle_precharge_control() {
           !datalayer.system.status.inverter_allows_contactor_closing ||
           datalayer.system.settings.equipment_stop_active || datalayer.battery.status.bms_status != FAULT) {
         datalayer.system.status.precharge_status = AUTO_PRECHARGE_IDLE;
-        pinMode(PRECHARGE_PIN, OUTPUT);
-        digitalWrite(PRECHARGE_PIN, LOW);
+        pinMode(HIA4V1_PIN, OUTPUT);
+        digitalWrite(HIA4V1_PIN, LOW);
 #ifdef DEBUG_LOG
         logging.printf("Precharge: equipment stop activated -> IDLE\n");
 #endif
diff --git a/Software/src/devboard/hal/hw_lilygo.h b/Software/src/devboard/hal/hw_lilygo.h
index 887f925f..8dbf4f74 100644
--- a/Software/src/devboard/hal/hw_lilygo.h
+++ b/Software/src/devboard/hal/hw_lilygo.h
@@ -53,6 +53,10 @@
 #define PRECHARGE_PIN 25
 #define BMS_POWER 18  // Note, this pin collides with CAN add-ons and Chademo
 
+// Automatic precharging
+#define HIA4V1_PIN 25
+#define INVERTER_DISCONNECT_CONTACTOR_PIN 32
+
 // SMA CAN contactor pins
 #define INVERTER_CONTACTOR_ENABLE_PIN 5
 
diff --git a/Software/src/devboard/hal/hw_stark.h b/Software/src/devboard/hal/hw_stark.h
index 064db9da..e5c0f986 100644
--- a/Software/src/devboard/hal/hw_stark.h
+++ b/Software/src/devboard/hal/hw_stark.h
@@ -51,6 +51,10 @@ GPIOs on extra header
 #define PRECHARGE_PIN 25
 #define BMS_POWER 23
 
+// Automatic precharging
+#define HIA4V1_PIN 19
+#define INVERTER_DISCONNECT_CONTACTOR_PIN 25
+
 // SMA CAN contactor pins
 #define INVERTER_CONTACTOR_ENABLE_PIN 19