diff --git a/pykirdy/driver/kirdy.py b/pykirdy/driver/kirdy.py
index 007e48b..cf2d59e 100644
--- a/pykirdy/driver/kirdy.py
+++ b/pykirdy/driver/kirdy.py
@@ -312,8 +312,8 @@ class Device:
                             'max': 3.0                  # Max Value Settable
                         }, 
                         'max_v': {                  # Max Voltage Across Tec Terminals (V)
-                            'value': 4.990857,          # Value Set
-                            'max': 5.0                  # Max Value Settable
+                            'value': 4.00000000,          # Value Set
+                            'max': 4.3                  # Max Value Settable
                         }, 
                         'max_i_pos': {              # Max Cooling Current Across Tec Terminals (A)
                             'value': 0.99628574,        # Value Set
diff --git a/pykirdy/kirdy_qt.py b/pykirdy/kirdy_qt.py
index 7c32408..92272a8 100644
--- a/pykirdy/kirdy_qt.py
+++ b/pykirdy/kirdy_qt.py
@@ -454,7 +454,7 @@ class MainWindow(QtWidgets.QMainWindow):
                     'unit': 'mA', 'lock': False, 'target': 'thermostat', 'action': 'set_tec_max_cooling_i', "compactHeight": False},
                 {'name': 'Max Heating Current', 'type': 'float', 'value': 0, 'step': 1, 'decimals': 6, 'limits': (0, 3000),
                     'unit': 'mA', 'lock': False, 'target': 'thermostat', 'action': 'set_tec_max_heating_i', "compactHeight": False},
-                {'name': 'Max Voltage Difference', 'type': 'float', 'value': 0, 'step': 0.1, 'limits': (0, 4),
+                {'name': 'Max Voltage Difference', 'type': 'float', 'value': 0, 'step': 0.1, 'limits': (0, 4.3),
                     'unit': 'V', 'lock': False, 'target': 'thermostat', 'action': 'set_tec_max_v', "compactHeight": False},
             ]},
             {'name': 'Default Power On', 'type': 'bool', 'value': False, 'lock': False, 'target': 'thermostat', 'action': 'set_default_pwr_on'},
diff --git a/src/thermostat/thermostat.rs b/src/thermostat/thermostat.rs
index 5df8068..d9f3cd4 100644
--- a/src/thermostat/thermostat.rs
+++ b/src/thermostat/thermostat.rs
@@ -70,7 +70,7 @@ impl TecSettings {
     pub const MAX_V_MAX: ElectricPotential = ElectricPotential {
         dimension: PhantomData,
         units: PhantomData,
-        value: 5.0,
+        value: 4.3,
     };
     const MAX_V_DUTY_MAX: f64 =
         TecSettings::MAX_V_MAX.value as f64 / TecSettings::MAX_V_DUTY_TO_VOLTAGE_RATE.value as f64;