diff --git a/src/laser_diode/laser_diode.rs b/src/laser_diode/laser_diode.rs
index d0750f4..b70111c 100644
--- a/src/laser_diode/laser_diode.rs
+++ b/src/laser_diode/laser_diode.rs
@@ -50,6 +50,7 @@ impl Settings{
 
 #[derive(Deserialize, Serialize, Clone, Copy, Debug, Tree)]
 struct Settings {
+    pwr_on: bool,
     ld_drive_current: ElectricCurrent,
     ld_drive_current_limit: ElectricCurrent,
     pd_responsitivity: pd_responsitivity::Parameters,
@@ -59,6 +60,7 @@ struct Settings {
 impl Default for Settings {
     fn default() -> Self {
         Self {
+            pwr_on: false,
             ld_drive_current: ElectricCurrent::new::<milliampere>(0.0),
             ld_drive_current_limit: ElectricCurrent::new::<milliampere>(0.0),
             pd_responsitivity: pd_responsitivity::Parameters::default(),
@@ -124,10 +126,12 @@ impl LdDrive{
         // Wait for LD Power Supply to start up before driving current to laser diode
         sleep(30);
         self.ld_set_i(self.settings.ld_drive_current);
+        self.settings.pwr_on = true;
     }
 
     pub fn power_down(&mut self){
         LdPwrExcProtector::pwr_off();
+        self.settings.pwr_on = false;
     }
 
     pub fn get_pd_i(&mut self) -> ElectricCurrent {
@@ -205,6 +209,7 @@ impl LdDrive{
     pub fn get_settings_summary(&mut self) -> LdSettingsSummary {
         let settings = self.settings;
         LdSettingsSummary {
+            pwr_on: self.settings.pwr_on,
             ld_drive_current: LdSettingsSummaryField { value: settings.ld_drive_current, max: Settings::LD_CURRENT_MAX},
             ld_drive_current_limit: LdSettingsSummaryField { value: settings.ld_drive_current_limit, max: Settings::LD_CURRENT_MAX},
             pd_responsitivity: settings.pd_responsitivity,
@@ -215,6 +220,7 @@ impl LdDrive{
 
 #[derive(Deserialize, Serialize, Copy, Clone, Debug, Tree)]
 pub struct LdSettingsSummary {
+    pwr_on: bool,
     ld_drive_current: LdSettingsSummaryField<ElectricCurrent>,
     ld_drive_current_limit: LdSettingsSummaryField<ElectricCurrent>,
     pd_responsitivity: pd_responsitivity::Parameters,
diff --git a/src/thermostat/thermostat.rs b/src/thermostat/thermostat.rs
index e35b253..a80ca40 100644
--- a/src/thermostat/thermostat.rs
+++ b/src/thermostat/thermostat.rs
@@ -28,6 +28,7 @@ pub const R_SENSE: ElectricalResistance = ElectricalResistance {
 
 #[derive(Deserialize, Serialize, Clone, Copy, Debug, Tree)]
 pub struct TecSettings {
+    pub pwr_on: bool,
     pub center_pt: ElectricPotential,
     pub max_v_set: ElectricPotential,
     pub max_i_pos_set: ElectricCurrent,
@@ -89,6 +90,7 @@ impl TecSettings{
 impl Default for TecSettings {
     fn default() -> Self {
         Self {
+            pwr_on: false,
             center_pt: ElectricPotential::new::<volt>(1.5),
             max_v_set: ElectricPotential::new::<volt>(5.0),
             max_i_pos_set: ElectricCurrent::new::<ampere>(1.0),
@@ -108,6 +110,7 @@ pub struct Thermostat {
 
 #[derive(Deserialize, Serialize, Copy, Clone, Debug, Tree)]
 pub struct ThermostatSettingsSummary {
+    pwr_on: bool,
     tec_settings: TecSettingSummary,
     pid_params: PidParams,
     temp_mon_settings: TempMonSettings,
@@ -187,12 +190,14 @@ impl Thermostat{
 
     pub fn power_up(&mut self){
         self.max1968.power_up();
+        self.tec_settings.pwr_on = true;
     }
 
     pub fn power_down(&mut self){
         self.max1968.power_down();
         self.pid_ctrl_ch0.reset_pid_state();
         self.set_i(ElectricCurrent::new::<ampere>(0.0));
+        self.tec_settings.pwr_on = true;
     }
 
     fn set_center_pt(&mut self, value: ElectricPotential){
@@ -384,6 +389,7 @@ impl Thermostat{
 
     pub fn get_settings_summary(&mut self) -> ThermostatSettingsSummary {
         ThermostatSettingsSummary {
+            pwr_on: self.tec_settings.pwr_on,
             tec_settings: self.get_tec_settings(),
             pid_params: self.get_pid_settings(),
             temp_mon_settings: self.get_temp_mon_settings(),