diff --git a/src/thermostat/max1968.rs b/src/thermostat/max1968.rs
index bb5a466..471df8a 100644
--- a/src/thermostat/max1968.rs
+++ b/src/thermostat/max1968.rs
@@ -12,7 +12,7 @@ use stm32f4xx_hal::{adc::{config::{self, AdcConfig},
                     timer::pwm::PwmChannel};
 use uom::si::{electric_potential::millivolt, f32::ElectricPotential, ratio::ratio};
 
-use crate::thermostat::ad5680;
+use crate::{device::sys_timer::sleep, thermostat::ad5680};
 
 pub const PWM_FREQ_KHZ: KilohertzU32 = KilohertzU32::from_raw(20);
 
@@ -77,6 +77,7 @@ pub struct MAX1968 {
     pub phy: MAX1968Phy<Channel0>,
     pub pins_adc: Adc<ADC1>,
     pub dma_adc: DMA_Transfer<Stream2<DMA2>, 1, Adc<ADC2>, PeripheralToMemory, &'static mut [u16; 16]>,
+    pub dac_out_range: ElectricPotential,
     prev_vtec_volt: ElectricPotential,
     prev_itec_volt: ElectricPotential,
 }
@@ -115,7 +116,7 @@ static mut ADC2_FIRST_BUFFER: [u16; 16] = [0; 16];
 static mut ADC2_LOCAL_BUFFER: [u16; 16] = [0; 16];
 
 impl MAX1968 {
-    pub fn new(phy_ch0: MAX1968Phy<Channel0>, adc1: ADC1, adc2: ADC2, dma2: DMA2) -> Self {
+    pub fn new(mut phy_ch0: MAX1968Phy<Channel0>, adc1: ADC1, adc2: ADC2, dma2: DMA2) -> Self {
         let adc_config = AdcConfig::default()
             .clock(config::Clock::Pclk2_div_8)
             .default_sample_time(config::SampleTime::Cycles_480);
@@ -221,11 +222,27 @@ impl MAX1968 {
             );
             NVIC::unmask(interrupt::DMA2_STREAM2);
         }
+        
+        phy_ch0.dac.set(ad5680::MAX_VALUE).unwrap();
+        sleep(500);
+        let mut sample = 0;
+        for _ in 0..512 {
+            sample += pins_adc1.convert(
+                &phy_ch0.dac_feedback_pin,
+                stm32f4xx_hal::adc::config::SampleTime::Cycles_480,
+            ) as u32;
+        }
+        let sample = sample / 512 as u32;
+        let mv = pins_adc1.sample_to_millivolts(sample as u16);
+        let dac_out_range = ElectricPotential::new::<millivolt>(mv as f32);
+        phy_ch0.dac.set(0).unwrap();
+
 
         MAX1968 {
             phy: phy_ch0,
             pins_adc: pins_adc1,
             dma_adc: dma_adc,
+            dac_out_range: dac_out_range,
             prev_vtec_volt: ElectricPotential::new::<millivolt>(0.0),
             prev_itec_volt: ElectricPotential::new::<millivolt>(0.0),
         }
diff --git a/src/thermostat/thermostat.rs b/src/thermostat/thermostat.rs
index fd88e80..1393fd8 100644
--- a/src/thermostat/thermostat.rs
+++ b/src/thermostat/thermostat.rs
@@ -47,11 +47,6 @@ pub struct TecSettings {
 }
 
 impl TecSettings {
-    pub const DAC_OUT_V_MAX: ElectricPotential = ElectricPotential {
-        dimension: PhantomData,
-        units: PhantomData,
-        value: 3.0,
-    };
     pub const TEC_VSEC_BIAS_V: ElectricPotential = ElectricPotential {
         dimension: PhantomData,
         units: PhantomData,
@@ -237,7 +232,8 @@ impl Thermostat {
 
     pub fn set_i(&mut self, i_tec: ElectricCurrent) -> ElectricCurrent {
         let voltage = i_tec * 10.0 * R_SENSE + self.tec_settings.center_pt;
-        let voltage = self.max1968.set_dac(voltage, TecSettings::DAC_OUT_V_MAX);
+        let voltage = self.max1968.set_dac(voltage, self.max1968.dac_out_range);
+
         self.tec_settings.i_set = (voltage - self.tec_settings.center_pt) / (10.0 * R_SENSE);
         self.tec_settings.i_set
     }
@@ -335,7 +331,7 @@ impl Thermostat {
                     best_error = error;
                     start_value = prev_value;
 
-                    let vref = (value as f32 / ad5680::MAX_VALUE as f32) * TecSettings::DAC_OUT_V_MAX;
+                    let vref = (value as f32 / ad5680::MAX_VALUE as f32) * self.max1968.dac_out_range;
                     self.set_center_pt(vref);
                 }
                 prev_value = value;