diff --git a/companion/src/simulation/simulatorinterface.h b/companion/src/simulation/simulatorinterface.h
index b04379b8e2b..f72f838b243 100644
--- a/companion/src/simulation/simulatorinterface.h
+++ b/companion/src/simulation/simulatorinterface.h
@@ -192,6 +192,7 @@ class SimulatorInterface : public QObject
     void auxSerialSetBaudrate(const quint8 port_num, const quint32 baudrate);
     void auxSerialStart(const quint8 port_num);
     void auxSerialStop(const quint8 port_num);
+    void txBatteryVoltageChanged(const int voltage);
 };
 
 class SimulatorFactory {
diff --git a/companion/src/simulation/simulatormainwindow.cpp b/companion/src/simulation/simulatormainwindow.cpp
index e9c6efff059..9a0f0cc759a 100644
--- a/companion/src/simulation/simulatormainwindow.cpp
+++ b/companion/src/simulation/simulatormainwindow.cpp
@@ -60,7 +60,11 @@ SimulatorMainWindow::SimulatorMainWindow(QWidget *parent, const QString & simula
   m_radioSizeConstraint(Qt::Horizontal | Qt::Vertical),
   m_firstShow(true),
   m_showRadioDocked(true),
-  m_showMenubar(true)
+  m_showMenubar(true),
+  m_batMin(0),
+  m_batMax(0),
+  m_batWarn(0),
+  m_batVoltage(0)
 {
   if (m_simulatorId.isEmpty()) {
     m_simulatorId = SimulatorLoader::findSimulatorByName(getCurrentFirmware()->getSimulatorId());
@@ -143,6 +147,7 @@ SimulatorMainWindow::SimulatorMainWindow(QWidget *parent, const QString & simula
   connect(ui->actionReloadRadioData, &QAction::triggered, this, &SimulatorMainWindow::simulatorRestart);
 
   connect(ui->actionReloadLua, &QAction::triggered, m_simulator, &SimulatorInterface::setLuaStateReloadPermanentScripts);
+  connect(ui->actionSetTxBatteryVoltage, &QAction::triggered, this, &SimulatorMainWindow::openTxBatteryVoltageDialog);
 
   if (m_outputsWidget) {
     connect(this, &SimulatorMainWindow::simulatorStart, m_outputsWidget, &RadioOutputsWidget::start);
@@ -154,6 +159,7 @@ SimulatorMainWindow::SimulatorMainWindow(QWidget *parent, const QString & simula
     connect(this, &SimulatorMainWindow::simulatorRestart, m_simulatorWidget, &SimulatorWidget::restart);
     connect(ui->actionScreenshot, &QAction::triggered, m_simulatorWidget, &SimulatorWidget::captureScreenshot);
     connect(m_simulatorWidget, &SimulatorWidget::windowTitleChanged, this, &SimulatorMainWindow::setWindowTitle);
+    connect(m_simulatorWidget, &SimulatorWidget::settingsBatteryChanged, this, &SimulatorMainWindow::onSettingsBatteryChanged);
   }
 
   connect(m_simulator, &SimulatorInterface::auxSerialSendData, hostSerialConnector, &HostSerialConnector::sendSerialData);
@@ -161,6 +167,7 @@ SimulatorMainWindow::SimulatorMainWindow(QWidget *parent, const QString & simula
   connect(m_simulator, &SimulatorInterface::auxSerialSetBaudrate, hostSerialConnector, &HostSerialConnector::setSerialBaudRate);
   connect(m_simulator, &SimulatorInterface::auxSerialStart, hostSerialConnector, &HostSerialConnector::serialStart);
   connect(m_simulator, &SimulatorInterface::auxSerialStop, hostSerialConnector, &HostSerialConnector::serialStop);
+  connect(m_simulator, &SimulatorInterface::txBatteryVoltageChanged, this, &SimulatorMainWindow::onTxBatteryVoltageChanged);
 }
 
 SimulatorMainWindow::~SimulatorMainWindow()
@@ -555,3 +562,49 @@ void SimulatorMainWindow::showAbout(bool show)
   msgBox.setText(aboutStr);
   msgBox.exec();
 }
+
+void SimulatorMainWindow::onSettingsBatteryChanged(const int batMin, const int batMax, const unsigned int batWarn)
+{
+  m_batMin = batMin;
+  m_batMax = batMax;
+  m_batWarn = batWarn;
+  m_batVoltage = batWarn + 5; // abitary +0.5V
+}
+
+void SimulatorMainWindow::openTxBatteryVoltageDialog()
+{
+  QDialog *dlg = new QDialog(this, Qt::WindowTitleHint | Qt::WindowSystemMenuHint);
+
+  QLabel *lbl = new QLabel(tr("Set voltage"));
+  QDoubleSpinBox *sb = new QDoubleSpinBox();
+  sb->setDecimals(1);
+  // vBatWarn is voltage in 100mV, vBatMin is in 100mV but with -9V offset, vBatMax has a -12V offset
+  sb->setMinimum((float)((m_batMin + 90) / 10.0f));
+  sb->setMaximum((float)((m_batMax + 120) / 10.0f));
+  sb->setSingleStep(0.1);
+  sb->setSuffix(tr("V"));
+  sb->setValue((float)m_batVoltage / 10.0f);
+
+  auto *btnBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
+  connect(btnBox, &QDialogButtonBox::accepted, dlg, &QDialog::accept);
+  connect(btnBox, &QDialogButtonBox::rejected, dlg, &QDialog::reject);
+
+  auto * lo = new QGridLayout(dlg);
+  lo->addWidget(lbl, 0, 0);
+  lo->addWidget(sb, 0, 1);
+  lo->addWidget(btnBox, 1, 0, 1, 2);
+
+  dlg->setWindowTitle(tr("Battery"));
+  dlg->deleteLater();
+
+  if(dlg->exec()) {
+    unsigned int volts = (unsigned int)((float)sb->value() * 10.0f);
+    m_batVoltage = volts;
+    emit txBatteryVoltageChanged(volts);
+  }
+}
+
+void SimulatorMainWindow::onTxBatteryVoltageChanged(const unsigned int voltage)
+{
+  m_batVoltage = voltage;
+}
diff --git a/companion/src/simulation/simulatormainwindow.h b/companion/src/simulation/simulatormainwindow.h
index cf4a426c19f..56771ac8934 100644
--- a/companion/src/simulation/simulatormainwindow.h
+++ b/companion/src/simulation/simulatormainwindow.h
@@ -71,6 +71,7 @@ class SimulatorMainWindow : public QMainWindow
   signals:
     void simulatorStart();
     void simulatorRestart();
+    void txBatteryVoltageChanged(int volts); // this changed value
 
   protected slots:
     virtual void closeEvent(QCloseEvent *);
@@ -84,6 +85,10 @@ class SimulatorMainWindow : public QMainWindow
     void openSerialPortsDialog(bool);
     void showHelp(bool show);
     void showAbout(bool show);
+    void openTxBatteryVoltageDialog();
+    // TODO: detect if changed via ui as currently event only on GeneralSettings (re)load
+    void onSettingsBatteryChanged(const int batMin, const int batMax, const unsigned int batWarn);
+    void onTxBatteryVoltageChanged(const unsigned int voltage); // something else changed voltage
 
   protected:
     void createDockWidgets();
@@ -114,6 +119,10 @@ class SimulatorMainWindow : public QMainWindow
     bool m_firstShow;
     bool m_showRadioDocked;
     bool m_showMenubar;
+    int m_batMin;
+    int m_batMax;
+    unsigned int m_batWarn;
+    unsigned int m_batVoltage;
 
     const static quint16 m_savedUiStateVersion;
 };
diff --git a/companion/src/simulation/simulatormainwindow.ui b/companion/src/simulation/simulatormainwindow.ui
index faf956160da..5179d15be7f 100644
--- a/companion/src/simulation/simulatormainwindow.ui
+++ b/companion/src/simulation/simulatormainwindow.ui
@@ -69,6 +69,7 @@
     <property name="title">
      <string>Tools</string>
     </property>
+    <addaction name="actionSetTxBatteryVoltage"/>
     <addaction name="actionScreenshot"/>
     <addaction name="actionJoystickSettings"/>
     <addaction name="actionSerialPorts"/>
@@ -234,6 +235,14 @@
     <string>About</string>
    </property>
   </action>
+  <action name="actionSetTxBatteryVoltage">
+   <property name="text">
+    <string>TX Battery Voltage...</string>
+   </property>
+   <property name="toolTip">
+    <string>Open set transmitter battery voltage dialog</string>
+   </property>
+  </action>
  </widget>
  <resources>
   <include location="../companion.qrc"/>
diff --git a/companion/src/simulation/simulatorwidget.cpp b/companion/src/simulation/simulatorwidget.cpp
index 3aaeebb1efd..f370c54019c 100644
--- a/companion/src/simulation/simulatorwidget.cpp
+++ b/companion/src/simulation/simulatorwidget.cpp
@@ -38,6 +38,7 @@
 #include "joystickdialog.h"
 #endif
 #include "simulateduiwidgetGeneric.h"
+#include "simulatormainwindow.h"
 
 #include <AppDebugMessageHandler>
 #include <QFile>
@@ -106,6 +107,8 @@ SimulatorWidget::SimulatorWidget(QWidget * parent, SimulatorInterface * simulato
   connect(simulator, &SimulatorInterface::runtimeError, this, &SimulatorWidget::onSimulatorError);
   connect(simulator, &SimulatorInterface::phaseChanged, this, &SimulatorWidget::onPhaseChanged);
 
+  connect((SimulatorMainWindow *)parent, &SimulatorMainWindow::txBatteryVoltageChanged, this, &SimulatorWidget::onTxBatteryVoltageChanged);
+
   m_timer.setInterval(SIMULATOR_INTERFACE_HEARTBEAT_PERIOD * 6);
   connect(&m_timer, &QTimer::timeout, this, &SimulatorWidget::onTimerEvent);
 
@@ -154,6 +157,7 @@ void SimulatorWidget::setPaths(const QString & sdPath, const QString & dataPath)
 void SimulatorWidget::setRadioSettings(const GeneralSettings settings)
 {
   radioSettings = settings;
+  emit settingsBatteryChanged(settings.vBatMin, settings.vBatMax, settings.vBatWarn);
 }
 
 /*
@@ -228,7 +232,7 @@ bool SimulatorWidget::setStartupData(const QByteArray & dataSource, bool fromFil
     return false;
   }
 
-  radioSettings = simuData.generalSettings;
+  setRadioSettings(simuData.generalSettings);
   startupFromFile = fromFile;
 
   return true;
@@ -259,7 +263,7 @@ bool SimulatorWidget::setRadioData(RadioData * radioData)
   }
 
   if (ret)
-    radioSettings = radioData->generalSettings;
+    setRadioSettings(radioData->generalSettings);
 
   return ret;
 }
@@ -670,8 +674,7 @@ void SimulatorWidget::restoreRadioWidgetsState()
   // Set throttle stick down and locked, side depends on mode
   emit stickModeChange(radioSettings.stickMode);
 
-  // TODO : custom voltages
-  qint16 volts = radioSettings.vBatWarn + 20; // 1V above min
+  qint16 volts = radioSettings.vBatWarn + 5; // +0.5V
   emit inputValueChange(SimulatorInterface::INPUT_SRC_TXVIN, 0, volts);
 }
 
@@ -686,7 +689,6 @@ void SimulatorWidget::saveRadioWidgetsState(QList<QByteArray> & state)
   }
 }
 
-
 /*
  * Event handlers/private slots
  */
@@ -889,3 +891,8 @@ void SimulatorWidget::onjoystickButtonValueChanged(int button, bool state)
   }
 #endif
 }
+
+void SimulatorWidget::onTxBatteryVoltageChanged(qint16 volts)
+{
+  emit inputValueChange(SimulatorInterface::INPUT_SRC_TXVIN, 0, volts);
+}
diff --git a/companion/src/simulation/simulatorwidget.h b/companion/src/simulation/simulatorwidget.h
index 0f1e9cafd5f..bcbb93f9469 100644
--- a/companion/src/simulation/simulatorwidget.h
+++ b/companion/src/simulation/simulatorwidget.h
@@ -99,6 +99,7 @@ class SimulatorWidget : public QWidget
     void simulatorStop();
     void simulatorSdPathChange(const QString & sdPath, const QString & dataPath);
     void simulatorVolumeGainChange(const int gain);
+    void settingsBatteryChanged(const int batMin, const int batMax, const unsigned int batWarn);
 
   private slots:
     virtual void mousePressEvent(QMouseEvent *event);
@@ -114,6 +115,7 @@ class SimulatorWidget : public QWidget
     void onRadioWidgetValueChange(const RadioWidget::RadioWidgetType type, int index, int value);
     void onjoystickAxisValueChanged(int axis, int value);
     void onjoystickButtonValueChanged(int button, bool state);
+    void onTxBatteryVoltageChanged(qint16 volts);
 
     void setRadioProfileId(int value);
     void setupRadioWidgets();
diff --git a/radio/src/hal/adc_driver.cpp b/radio/src/hal/adc_driver.cpp
index 144098f7212..33f0bb0c91c 100644
--- a/radio/src/hal/adc_driver.cpp
+++ b/radio/src/hal/adc_driver.cpp
@@ -67,7 +67,7 @@ static bool adcSingleRead()
 bool adcRead()
 {
   adcSingleRead();
-  
+
   // TODO: this hack needs to go away...
   if (isVBatBridgeEnabled()) {
     disableVBatBridge();
diff --git a/radio/src/targets/simu/adc_driver.cpp b/radio/src/targets/simu/adc_driver.cpp
index 3e6f6deda1e..376592554b8 100644
--- a/radio/src/targets/simu/adc_driver.cpp
+++ b/radio/src/targets/simu/adc_driver.cpp
@@ -27,6 +27,7 @@
 
 #include "hal_adc_inputs.inc"
 #include "board.h"
+#include "edgetx.h"
 
 void enableVBatBridge(){}
 void disableVBatBridge(){}
@@ -41,18 +42,35 @@ static bool simu_start_conversion()
     setAnalogValue(i, simu_get_analog(i));
   }
 
-  // set VBAT / RTC_BAT
-  if (adcGetMaxInputs(ADC_INPUT_VBAT) > 0) {
+  // set batteries default voltages
+  int i = adcGetInputOffset(ADC_INPUT_VBAT);
+
+  if (i > 0) {
+    // calculate default voltage on 1st call
+    uint32_t adc = (simu_get_analog(i) - 2048) * 1000 / 2000;
+    // TRACE("raw ana: %d adj ana: %d", simu_get_analog(i), vbat);
+    // just in case the voltage has not been initialised in sim initialisation/startup
+    // these formulae must mirror OpenTxSimulator::voltageToAdc
+    if (adc == 0) {
+      uint32_t volts = (uint32_t)((g_eeGeneral.vBatWarn > 0 ? g_eeGeneral.vBatWarn : BATTERY_WARN) + 5) * 10; // +0.5V and prec2
 #if defined(VBAT_MOSFET_DROP)
-    uint32_t vbat = (2 * (BATTERY_MAX + BATTERY_MIN) * (VBAT_DIV_R2 + VBAT_DIV_R1)) / VBAT_DIV_R1;
+      // TRACE("volts: %d r1: %d r2: %d drop: %d vref: %d calib: %d", volts, VBAT_DIV_R1, VBAT_DIV_R2, VBAT_MOSFET_DROP, ADC_VREF_PREC2, g_eeGeneral.txVoltageCalibration);
+      adc = (volts - VBAT_MOSFET_DROP) * (2 * RESX * 1000) / ADC_VREF_PREC2 / (((1000 + g_eeGeneral.txVoltageCalibration) * (VBAT_DIV_R2 + VBAT_DIV_R1)) / VBAT_DIV_R1);
 #elif defined(BATT_SCALE)
-    uint32_t vbat = (BATTERY_MAX + BATTERY_MIN) * 5; // * 10 / 2
-    vbat = ((vbat - VOLTAGE_DROP) * BATTERY_DIVIDER) / (BATT_SCALE * 128);
+      // TRACE("volts: %d div: %d drop: %d scale: %d calib: %d", volts, BATTERY_DIVIDER, VOLTAGE_DROP, BATT_SCALE, g_eeGeneral.txVoltageCalibration);
+      adc = (volts - VOLTAGE_DROP) * BATTERY_DIVIDER / (128 + g_eeGeneral.txVoltageCalibration) / BATT_SCALE;
+#elif defined(VOLTAGE_DROP)
+      // TRACE("volts: %d div: %d drop: %d", volts, BATTERY_DIVIDER, VOLTAGE_DROP);
+      adc = (volts - VOLTAGE_DROP) * BATTERY_DIVIDER / (1000 + g_eeGeneral.txVoltageCalibration);
 #else
-    uint32_t vbat = (BATTERY_MAX + BATTERY_MIN) * 5; // * 10 / 2
-    vbat = (vbat * BATTERY_DIVIDER) / 1000;
+      // TRACE("volts: %d div: %d calib: %d", volts, BATTERY_DIVIDER, g_eeGeneral.txVoltageCalibration);
+      adc = volts * BATTERY_DIVIDER / (1000 + g_eeGeneral.txVoltageCalibration);
 #endif
-    setAnalogValue(adcGetInputOffset(ADC_INPUT_VBAT), vbat * 2);
+      // TRACE("calc adc: %d", adc);
+      adc = adc * 2; // div by 2 in firmware filtered adc calcs
+    }
+
+    setAnalogValue(i, adc);
   }
 
   if (adcGetMaxInputs(ADC_INPUT_RTC_BAT) > 0) {
diff --git a/radio/src/targets/simu/opentxsimulator.cpp b/radio/src/targets/simu/opentxsimulator.cpp
index 6cb84ab2f73..bf7bfb1967b 100644
--- a/radio/src/targets/simu/opentxsimulator.cpp
+++ b/radio/src/targets/simu/opentxsimulator.cpp
@@ -24,6 +24,7 @@
 #include "simulcd.h"
 #include "switches.h"
 #include "serial.h"
+#include "myeeprom.h"
 
 #include "hal/adc_driver.h"
 #include "hal/rotary_encoder.h"
@@ -61,6 +62,8 @@ extern etx_serial_port_t * serialPorts[MAX_AUX_SERIAL];
 
 uint16_t simu_get_analog(uint8_t idx)
 {
+  // TODO: return raw values for ADC_INPUT_VBAT and ADC_INPUT_RTC_BAT
+
   // 6POS simu mechanism use a different scale, so needs specific offset
   if (IS_POT_MULTIPOS(idx - adcGetInputOffset(ADC_INPUT_FLEX))) {
     // Use radio calibration data to determine conversion factor
@@ -182,7 +185,7 @@ OpenTxSimulator::OpenTxSimulator() :
   tracebackDevices.clear();
   traceCallback = firmwareTraceCb;
 
-  // When we create the simulator, we change the UART driver 
+  // When we create the simulator, we change the UART driver
   for (int i = 0; i < MAX_AUX_SERIAL; i++) {
     etx_serial_port_t * port = serialPorts[i];
     if (port != nullptr) {
@@ -377,6 +380,7 @@ void OpenTxSimulator::setInputValue(int type, uint8_t index, int16_t value)
       if (adcGetMaxInputs(ADC_INPUT_VBAT) > 0) {
         auto idx = adcGetInputOffset(ADC_INPUT_VBAT);
         setAnalogValue(idx, voltageToAdc(value));
+        emit txBatteryVoltageChanged((unsigned int)value);
       }
       break;
     case INPUT_SRC_SWITCH :
@@ -891,17 +895,26 @@ const char * OpenTxSimulator::getError()
   return main_thread_error;
 }
 
-const int OpenTxSimulator::voltageToAdc(const int volts)
+const int OpenTxSimulator::voltageToAdc(const int voltage)
 {
-  int ret = 0;
-#if defined(PCBHORUS) || defined(PCBX7)
-  ret = (float)volts * 16.2f;
-#elif defined(PCBTARANIS)
-  ret = (float)volts * 13.3f;
+  int volts = voltage * 10;  // prec2
+  int adc = 0;
+
+#if defined(VBAT_MOSFET_DROP)
+  // TRACE("volts: %d r1: %d r2: %d drop: %d vref: %d calib: %d", volts, VBAT_DIV_R1, VBAT_DIV_R2, VBAT_MOSFET_DROP, ADC_VREF_PREC2, g_eeGeneral.txVoltageCalibration);
+  adc = (volts - VBAT_MOSFET_DROP) * (2 * RESX * 1000) / ADC_VREF_PREC2 / (((1000 + g_eeGeneral.txVoltageCalibration) * (VBAT_DIV_R2 + VBAT_DIV_R1)) / VBAT_DIV_R1);
+#elif defined(BATT_SCALE)
+  // TRACE("volts: %d div: %d drop: %d scale: %d calib: %d", volts, BATTERY_DIVIDER, VOLTAGE_DROP, BATT_SCALE, g_eeGeneral.txVoltageCalibration);
+  adc = (volts - VOLTAGE_DROP) * BATTERY_DIVIDER / (128 + g_eeGeneral.txVoltageCalibration) / BATT_SCALE;
+#elif defined(VOLTAGE_DROP)
+  // TRACE("volts: %d div: %d drop: %d", volts, BATTERY_DIVIDER, VOLTAGE_DROP);
+  adc = (volts - VOLTAGE_DROP) * BATTERY_DIVIDER / (1000 + g_eeGeneral.txVoltageCalibration);
 #else
-  ret = (float)volts * 14.15f;
+  // TRACE("volts: %d div: %d calib: %d", volts, BATTERY_DIVIDER, g_eeGeneral.txVoltageCalibration);
+  adc = volts * BATTERY_DIVIDER / (1000 + g_eeGeneral.txVoltageCalibration);
 #endif
-  return ret;
+  // TRACE("calc adc: %d", adc);
+  return adc * 2; // div by 2 in firmware filtered adc calcs
 }
 
 
diff --git a/radio/src/targets/simu/opentxsimulator.h b/radio/src/targets/simu/opentxsimulator.h
index 2b61786c8d4..faac99fe3b8 100644
--- a/radio/src/targets/simu/opentxsimulator.h
+++ b/radio/src/targets/simu/opentxsimulator.h
@@ -106,7 +106,7 @@ class DLLEXPORT OpenTxSimulator : public SimulatorInterface
     const char * getPhaseName(unsigned int phase);
     const QString getCurrentPhaseName();
     const char * getError();
-    const int voltageToAdc(const int volts);
+    const int voltageToAdc(const int voltage);
 
     QString simuSdDirectory;
     QString simuSettingsDirectory;