diff --git a/config/board.3drag.h b/config/board.3drag.h
index 46f3c45..0deb584 100644
--- a/config/board.3drag.h
+++ b/config/board.3drag.h
@@ -237,11 +237,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO14, THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO10,   0,      1)
-DEFINE_HEATER(bed,      DIO9,    0,      1)
-DEFINE_HEATER(fan,      DIO8,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO10,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO9,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO8,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.cnc-shield-v3-nucleo.h b/config/board.cnc-shield-v3-nucleo.h
index d91576f..712087f 100644
--- a/config/board.cnc-shield-v3-nucleo.h
+++ b/config/board.cnc-shield-v3-nucleo.h
@@ -235,8 +235,8 @@ DEFINE_TEMP_SENSOR(extruder, TT_THERMISTOR, PB_0,  THERMISTOR_EXTRUDER)
   influenced globally with FAST_PWM, see below.
 */
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, PA_5,    0,      10000)
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, PA_5,    0,      10000,   100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 //DEFINE_HEATERS_END
diff --git a/config/board.cnc-shield-v3.h b/config/board.cnc-shield-v3.h
index 38eb6e7..078dea2 100644
--- a/config/board.cnc-shield-v3.h
+++ b/config/board.cnc-shield-v3.h
@@ -237,9 +237,22 @@ DEFINE_TEMP_SENSOR(extruder, TT_THERMISTOR, AIO3,  THERMISTOR_EXTRUDER)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, AIO2,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, AIO2,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 //DEFINE_HEATERS_END
diff --git a/config/board.gen3.h b/config/board.gen3.h
index 4dfb42c..6764a97 100644
--- a/config/board.gen3.h
+++ b/config/board.gen3.h
@@ -231,8 +231,21 @@ DEFINE_TEMP_SENSOR(noheater, TT_INTERCOM,   AIO0,  0)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
+
+//            name      pin      invert  pwm      max_pwm
 
 //DEFINE_HEATERS_END
 
diff --git a/config/board.gen6.h b/config/board.gen6.h
index 1330ac9..dcc9103 100644
--- a/config/board.gen6.h
+++ b/config/board.gen6.h
@@ -232,9 +232,22 @@ DEFINE_TEMP_SENSOR(extruder, TT_THERMISTOR, AIO5,  THERMISTOR_EXTRUDER)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO6,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO6,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 //DEFINE_HEATERS_END
diff --git a/config/board.gen7-arm.h b/config/board.gen7-arm.h
index ca87925..2c4da4e 100644
--- a/config/board.gen7-arm.h
+++ b/config/board.gen7-arm.h
@@ -245,10 +245,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, PIO1_0,THERMISTOR_BED)
 
   Pins which don't allow PWM are always operated in on/off mode.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, PIO0_10, 0,      20000)
-DEFINE_HEATER(bed,      PIO1_9,  1,      10)
+
+//            name      pin      invert  pwm        max_pwm
+DEFINE_HEATER(extruder, PIO0_10, 0,      20000,     100)
+DEFINE_HEATER(bed,      PIO1_9,  1,      10,        100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.gen7-v1.1-v1.3.h b/config/board.gen7-v1.1-v1.3.h
index 58d6b90..8187c52 100644
--- a/config/board.gen7-v1.1-v1.3.h
+++ b/config/board.gen7-v1.1-v1.3.h
@@ -241,10 +241,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO2,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO4,    0,      1)
-DEFINE_HEATER(bed,      DIO3,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO4,    0,      1,       100)
+DEFINE_HEATER(bed,      DIO3,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.gen7-v1.4.h b/config/board.gen7-v1.4.h
index e1d85bd..ab3e385 100644
--- a/config/board.gen7-v1.4.h
+++ b/config/board.gen7-v1.4.h
@@ -242,10 +242,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO0,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO4,    0,      1)
-DEFINE_HEATER(bed,      DIO3,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO4,    0,      1,       100)
+DEFINE_HEATER(bed,      DIO3,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.melzi.h b/config/board.melzi.h
index 37aaf30..e12a710 100644
--- a/config/board.melzi.h
+++ b/config/board.melzi.h
@@ -241,11 +241,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO13,   0,      1)
-DEFINE_HEATER(bed,      DIO12,   0,      1)
-DEFINE_HEATER(fan,      DIO4,    0,      0)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO13,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO12,   0,      1,       100)
+DEFINE_HEATER(fan,      DIO4,    0,      0,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.nanoheart-v1.0.h b/config/board.nanoheart-v1.0.h
index 788836b..2070cf8 100644
--- a/config/board.nanoheart-v1.0.h
+++ b/config/board.nanoheart-v1.0.h
@@ -239,10 +239,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO7,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO11,   0,      1)
-DEFINE_HEATER(bed,      DIO3,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO11,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO3,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.pcbscriber.h b/config/board.pcbscriber.h
index 1fb1f73..875af5b 100644
--- a/config/board.pcbscriber.h
+++ b/config/board.pcbscriber.h
@@ -258,9 +258,22 @@
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(drill,    DIO16,    0,      0)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(drill,    DIO16,    0,      0,      100)
 
 #define HEATER_DRILL HEATER_drill
 //DEFINE_HEATERS_END
diff --git a/config/board.ramps-v1.2.h b/config/board.ramps-v1.2.h
index f1cdfa7..d0d6322 100644
--- a/config/board.ramps-v1.2.h
+++ b/config/board.ramps-v1.2.h
@@ -238,11 +238,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO1,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO10,   0,      1)
-DEFINE_HEATER(bed,      DIO8,    0,      1)
-DEFINE_HEATER(fan,      DIO9,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO10,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO8,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO9,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.ramps-v1.3.h b/config/board.ramps-v1.3.h
index 7bb57ce..9f2c329 100644
--- a/config/board.ramps-v1.3.h
+++ b/config/board.ramps-v1.3.h
@@ -243,11 +243,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO14, THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO10,   0,      1)
-DEFINE_HEATER(bed,      DIO8,    0,      1)
-DEFINE_HEATER(fan,      DIO9,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO10,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO8,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO9,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.rumba.h b/config/board.rumba.h
index c3f1490..433985d 100644
--- a/config/board.rumba.h
+++ b/config/board.rumba.h
@@ -241,11 +241,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO11, THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO2,    0,      1)
-DEFINE_HEATER(bed,      DIO9,    0,      1)
-DEFINE_HEATER(fan,      DIO8,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO2,    0,      1,       100)
+DEFINE_HEATER(bed,      DIO9,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO8,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.sanguinololu-v1.1.h b/config/board.sanguinololu-v1.1.h
index e0a9889..fd5b8a2 100644
--- a/config/board.sanguinololu-v1.1.h
+++ b/config/board.sanguinololu-v1.1.h
@@ -239,10 +239,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO13,   0,      1)
-DEFINE_HEATER(bed,      DIO14,   0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO13,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO14,   0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.sanguinololu-v1.2.h b/config/board.sanguinololu-v1.2.h
index 9a2e6e3..20d0317 100644
--- a/config/board.sanguinololu-v1.2.h
+++ b/config/board.sanguinololu-v1.2.h
@@ -239,10 +239,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO12,   0,      1)
-DEFINE_HEATER(bed,      DIO13,   0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO12,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO13,   0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.sanguish.h b/config/board.sanguish.h
index 0578fca..7c25c59 100644
--- a/config/board.sanguish.h
+++ b/config/board.sanguish.h
@@ -239,10 +239,23 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO0,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO3,    0,      1)
-DEFINE_HEATER(bed,      DIO4,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO3,    0,      1,       100)
+DEFINE_HEATER(bed,      DIO4,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.sinaptec-at328-02.h b/config/board.sinaptec-at328-02.h
index 6149b6f..f646e1d 100644
--- a/config/board.sinaptec-at328-02.h
+++ b/config/board.sinaptec-at328-02.h
@@ -240,11 +240,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO3,    0,      1)
-DEFINE_HEATER(bed,      DIO6,    0,      1)
-DEFINE_HEATER(fan,      DIO5,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO3,    0,      1,       100)
+DEFINE_HEATER(bed,      DIO6,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO5,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.teensy++-v2.0.h b/config/board.teensy++-v2.0.h
index 0d6d4ea..c5d217f 100644
--- a/config/board.teensy++-v2.0.h
+++ b/config/board.teensy++-v2.0.h
@@ -237,11 +237,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO15,   0,      1)
-DEFINE_HEATER(bed,      DIO14,   0,      1)
-DEFINE_HEATER(fan,      DIO16,   0,      0)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO15,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO14,   0,      1,       100)
+DEFINE_HEATER(fan,      DIO16,   0,      0,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.teensy-v2.0.h b/config/board.teensy-v2.0.h
index f910a78..2e718e2 100644
--- a/config/board.teensy-v2.0.h
+++ b/config/board.teensy-v2.0.h
@@ -237,11 +237,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO0,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO10,   0,      1)
-DEFINE_HEATER(bed,      DIO9,    0,      1)
-DEFINE_HEATER(fan,      DIO8,    0,      0)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO10,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO9,    0,      1,       100)
+DEFINE_HEATER(fan,      DIO8,    0,      0,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/config/board.tronxy.h b/config/board.tronxy.h
index 2c782be..f672d10 100644
--- a/config/board.tronxy.h
+++ b/config/board.tronxy.h
@@ -239,11 +239,24 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO6,  THERMISTOR_BED)
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+// #define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
-//            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO13,   0,      1)
-DEFINE_HEATER(bed,      DIO12,   0,      1)
-DEFINE_HEATER(fan,      DIO4,    0,      1)
+
+//            name      pin      invert  pwm      max_pwm
+DEFINE_HEATER(extruder, DIO13,   0,      1,       100)
+DEFINE_HEATER(bed,      DIO12,   0,      1,       100)
+DEFINE_HEATER(fan,      DIO4,    0,      1,       100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/configtool/addheaterdlg.py b/configtool/addheaterdlg.py
index 753ea16..a663931 100644
--- a/configtool/addheaterdlg.py
+++ b/configtool/addheaterdlg.py
@@ -5,7 +5,7 @@ from configtool.data import BSIZESMALL, offsetChLabel, offsetTcLabel
 
 class AddHeaterDlg(wx.Dialog):
   def __init__(self, parent, names, pins, font,
-               name = "", pin = "", invert = "0", pwm = "1"):
+               name = "", pin = "", invert = "0", pwm = "1", max_pwm = "100"):
     wx.Dialog.__init__(self, parent, wx.ID_ANY, "Add heater", size = (400, 204))
     self.SetFont(font)
     self.Bind(wx.EVT_CLOSE, self.onCancel)
@@ -14,6 +14,7 @@ class AddHeaterDlg(wx.Dialog):
     self.choices = pins
 
     self.nameValid = (name != "")
+    self.maxPWMValid = (max_pwm != "")
 
     sz = wx.BoxSizer(wx.VERTICAL)
     gsz = wx.GridBagSizer()
@@ -50,10 +51,26 @@ class AddHeaterDlg(wx.Dialog):
     else:
       self.chPin.SetSelection(i)
     lsz.Add(self.chPin)
-    self.chPin.SetToolTipString("Choose a pin for this heater.")
+    self.chPin.SetToolTipString("Choose a pin for this heater.")    
 
     gsz.Add(lsz, pos = (3, 1))
 
+    lsz = wx.BoxSizer(wx.HORIZONTAL)
+    st = wx.StaticText(self, wx.ID_ANY, "Max PWM:", size = (80, -1),
+                       style = wx.ALIGN_RIGHT)
+    st.SetFont(font)
+    lsz.Add(st, 1, wx.TOP, offsetChLabel)
+
+    self.tcMaxPWM = wx.TextCtrl(self, wx.ID_ANY, max_pwm)
+    self.tcMaxPWM.SetFont(font)
+    self.tcMaxPWM.Bind(wx.EVT_TEXT, self.onMaxPWM)
+    lsz.Add(self.tcMaxPWM)
+    self.tcMaxPWM.SetToolTipString("Enter max. PWM value in [%]. Typically \n"
+                                      "between 40 and 100. Standard is 100.\n"
+                                      "Valid values 1 to 100.")
+
+    gsz.Add(lsz, pos = (5, 1))
+
     self.cbInv = wx.CheckBox(self, wx.ID_ANY, "Invert")
     self.cbInv.SetFont(font)
     self.cbInv.SetValue(int(invert) != 0)
@@ -118,8 +135,29 @@ class AddHeaterDlg(wx.Dialog):
   def onChoice(self, evt):
     pass
 
+  def onMaxPWM(self, evt):
+    tc = evt.GetEventObject()
+    w = tc.GetValue().strip()
+    if w == "":
+      self.maxPWMValid = False
+    else:
+      if int(w) > 0 and int(w) <= 100:
+        self.maxPWMValid = True
+      else:
+        self.maxPWMValid = False
+
+    if self.maxPWMValid:
+      tc.SetBackgroundColour(wx.SystemSettings_GetColour(wx.SYS_COLOUR_WINDOW))
+    else:
+      tc.SetBackgroundColour("pink")
+    tc.Refresh()
+
+    self.checkDlgValidity()
+    if evt is not None:
+      evt.Skip()
+
   def checkDlgValidity(self):
-    if self.nameValid:
+    if (self.nameValid and self.maxPWMValid):
       self.bSave.Enable(True)
     else:
       self.bSave.Enable(False)
@@ -138,7 +176,9 @@ class AddHeaterDlg(wx.Dialog):
     else:
       pwm = "0"
 
-    return (nm, pin, invert, pwm)
+    max_pwm = self.tcMaxPWM.GetValue()
+
+    return (nm, pin, invert, pwm, max_pwm)
 
   def onSave(self, evt):
     self.EndModal(wx.ID_OK)
diff --git a/configtool/board.generic.h b/configtool/board.generic.h
index 3e1550d..9400995 100644
--- a/configtool/board.generic.h
+++ b/configtool/board.generic.h
@@ -233,6 +233,18 @@
   with slow switches, like solid state relays. PWM frequency can be
   influenced globally with FAST_PWM, see below.
 */
+
+/** \def MAX_PWM_ACTIVE
+  Enable max_pwm value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the max_pwm to 25%.
+  
+  max_pwm values are allowed between 1 and 100.
+*/
+#define MAX_PWM_ACTIVE
+
 //DEFINE_HEATERS_START
 //DEFINE_HEATERS_END
 
diff --git a/configtool/board.py b/configtool/board.py
index 69fcb0d..211489e 100644
--- a/configtool/board.py
+++ b/configtool/board.py
@@ -12,7 +12,7 @@ from configtool.data import (defineValueFormat,
                              reDefine, reDefineBL, reDefQS, reDefQSm,
                              reDefQSm2, reDefBool, reDefBoolBL, reDefHT,
                              reDefTS, reDefTT, reSensor, reHeater3, reHeater4,
-                             reTempTable4, reTempTable7)
+                             reHeater5, reTempTable4, reTempTable7)
 
 class Board:
   def __init__(self, settings):
@@ -303,11 +303,19 @@ class Board:
     return None
 
   def parseHeater(self, s):
+    m = reHeater5.search(s)
+    if m:
+      t = m.groups()
+      if len(t) == 5:
+        return list(t)
+    # reHeater4 deprecated, for compatibility with old config files only.
     m = reHeater4.search(s)
     if m:
       t = m.groups()
       if len(t) == 4:
-        return list(t)
+        t = list(t)
+        t.insert(5, '100')
+        return t
     # reHeater3 deprecated, for compatibility with old config files only.
     m = reHeater3.search(s)
     if m:
@@ -315,6 +323,7 @@ class Board:
       if len(t) == 3:
         t = list(t)
         t.insert(2, '0')
+        t.insert(5, '100')
         return t
     # End of deprecated part.
     return None
@@ -392,10 +401,10 @@ class Board:
       m = reStartHeaters.match(ln)
       if m:
         fp.write(ln)
-        fp.write("//            name      pin      invert  pwm\n")
+        fp.write("//            name      pin      invert  pwm     max_pwm\n")
         for s in self.heaters:
-          sstr = "%-10s%-9s%-8s%s" % ((s[0] + ","), (s[1] + ","),
-                                      (s[2] + ","), s[3])
+          sstr = "%-10s%-9s%-8s%-7s%s" % ((s[0] + ","), (s[1] + ","),
+                                      (s[2] + ","), s[3] + ",", s[4])
           fp.write("DEFINE_HEATER(%s)\n" % sstr)
         fp.write("\n")
         for s in self.heaters:
diff --git a/configtool/data.py b/configtool/data.py
index e5f23fa..4c459c9 100644
--- a/configtool/data.py
+++ b/configtool/data.py
@@ -61,9 +61,10 @@ reHelpTextEnd = re.compile("^\s*\*/")
 reHelpText = re.compile("/\*\*.*?\*/\r?\n", re.DOTALL)
 
 reSensor = re.compile(".*\\(\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*\\)")
-# reHeater3 deprecated, for compatibility with old config files only.
+# reHeater3 and reHeater4 deprecated, for compatibility with old config files only.
 reHeater3 = re.compile(".*\\(\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*\\)")
 reHeater4 = re.compile(".*\\(\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*\\)")
+reHeater5 = re.compile(".*\\(\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*,\s*(\w+)\s*\\)")
 reTempTable4 = re.compile(".*\\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d*.?\d*)\s*\\)")
 reTempTable7 = re.compile(".*\\(\s*(\d+)\s*,\s*(\d*.?\d*)\s*,\s*(\d+)\s*,\s*(\d*.?\d*)\s*,\s*(\d+)\s*,\s*(\d*.?\d*)\s*,\s*(\d+)\s*\\)")
 
diff --git a/configtool/heaterlist.py b/configtool/heaterlist.py
index 094c9c5..28c7b4f 100644
--- a/configtool/heaterlist.py
+++ b/configtool/heaterlist.py
@@ -7,7 +7,7 @@ class HeaterList(wx.ListCtrl):
     self.parent = parent
     self.currentItem = None
     wx.ListCtrl.__init__(self, parent, wx.ID_ANY,
-                         size = (95 + 75 + 55 + 55 + 4, 100),
+                         size = (95 + 75 + 55 + 55 + 95 + 4, 100),
                          style = wx.LC_REPORT | wx.LC_VIRTUAL | wx.LC_HRULES |
                          wx.LC_VRULES)
     self.SetFont(font)
@@ -19,10 +19,12 @@ class HeaterList(wx.ListCtrl):
     self.InsertColumn(1, "Pin")
     self.InsertColumn(2, "Invert")
     self.InsertColumn(3, "PWM")
+    self.InsertColumn(4, "Max PWM [%]")
     self.SetColumnWidth(0, 95)
     self.SetColumnWidth(1, 75)
     self.SetColumnWidth(2, 55)
     self.SetColumnWidth(3, 55)
+    self.SetColumnWidth(4, 95)
 
     self.SetItemCount(0)
 
@@ -84,3 +86,5 @@ class HeaterList(wx.ListCtrl):
         return "True"
       else:
         return "False"
+    elif col == 4:
+      return s[4]
diff --git a/configtool/heaterspage.py b/configtool/heaterspage.py
index ce98559..b4ea085 100644
--- a/configtool/heaterspage.py
+++ b/configtool/heaterspage.py
@@ -14,6 +14,8 @@ class HeatersPage(wx.Panel, Page):
     self.font = font
     self.id = idPg
 
+    self.labels = {'MAX_PWM_ACTIVE':"Activate max. PWM [%]"}
+
     sz = wx.GridBagSizer()
     sz.AddSpacer((30, 30), pos = (0, 0))
 
@@ -24,6 +26,13 @@ class HeatersPage(wx.Panel, Page):
     sz.Add(self.lb, pos = (1, 1))
     sz.AddSpacer((20, 20), pos = (1, 2))
 
+    k = 'MAX_PWM_ACTIVE'
+    cb = self.addCheckBox(k, self.onCheckBox)
+    cb.SetToolTipString("Enable all max. PWM [%] values.")
+
+    sz.Add(cb, pos = (2, 1))
+    sz.AddSpacer((20, 20), pos = (2, 2))
+
     bsz = wx.BoxSizer(wx.VERTICAL)
 
     self.bAdd = wx.Button(self, wx.ID_ANY, "Add", size = BSIZESMALL)
@@ -116,7 +125,7 @@ class HeatersPage(wx.Panel, Page):
     h = self.heaters[self.selection]
 
     dlg = AddHeaterDlg(self, nm, [h[1]] + self.getFreePins(), self.font,
-                       name = h[0], pin = h[1], invert = h[2], pwm = h[3])
+                       name = h[0], pin = h[1], invert = h[2], pwm = h[3], max_pwm = h[4])
     rc = dlg.ShowModal()
     if rc == wx.ID_OK:
       ht = dlg.getValues()
diff --git a/heater-avr.c b/heater-avr.c
index c8a6dc8..7bc8a0d 100644
--- a/heater-avr.c
+++ b/heater-avr.c
@@ -21,12 +21,26 @@ typedef struct {
   /// Wether the heater pin signal needs to be inverted.
   uint8_t          invert;
 	volatile uint8_t *heater_pwm;  ///< pointer to 8-bit PWM register, eg OCR0A (8-bit) or ORC3L (low byte, 16-bit)
+  #ifdef MAX_PWM_ACTIVE
+    uint16_t max_value;
+  #endif
 } heater_definition_t;
 
+#ifdef MAX_PWM_ACTIVE
+  #define HEATER_MAX_VALUE(max_value) (max_value * 64 + 12) / 25) /* scale 100% = 256 */
+#else
+  #define HEATER_MAX_VALUE(dummy)
+#endif
+
 #undef DEFINE_HEATER
 /// \brief helper macro to fill heater definition struct from config.h
-#define	DEFINE_HEATER(name, pin, invert, pwm) { \
-  &(pin ## _WPORT), pin ## _PIN, invert ? 1 : 0, pwm ? (pin ## _PWM) : NULL},
+#define	DEFINE_HEATER(name, pin, invert, pwm, max_value) { \
+  &(pin ## _WPORT), \
+  pin ## _PIN, \
+  invert ? 1 : 0, \
+  pwm ? (pin ## _PWM) : NULL, \
+  HEATER_MAX_VALUE(max_value)\
+  },
 static const heater_definition_t heaters[NUM_HEATERS] =
 {
 	#include	"config_wrapper.h"
@@ -195,7 +209,7 @@ void heater_init() {
 
 	// set all heater pins to output
   #undef DEFINE_HEATER
-  #define DEFINE_HEATER(name, pin, invert, pwm) \
+  #define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
     SET_OUTPUT(pin);                            \
     WRITE(pin, invert ? 1 : 0);
   #include "config_wrapper.h"
@@ -214,6 +228,9 @@ void heater_set(heater_t index, uint8_t value) {
 	if (index >= NUM_HEATERS)
 		return;
 
+  #ifdef MAX_PWM_ACTIVE
+    value = (uint8_t)((heaters[index].max_value * value + 128) / 256);
+  #endif
 	heaters_runtime[index].heater_output = value;
 
 	if (heaters[index].heater_pwm) {
diff --git a/heater-lpc.c b/heater-lpc.c
index 5c96d49..46736d0 100644
--- a/heater-lpc.c
+++ b/heater-lpc.c
@@ -51,7 +51,11 @@
   frequency, so you should bother about PWM_SCALE only of you need frequencies
   below 3 Hz.
 */
-#define PWM_SCALE 255
+#ifndef MAX_PWM_ACTIVE
+  #define PWM_SCALE 255
+#else
+  #define PWM_SCALE 1020
+#endif
 
 /** \struct heater_definition_t
 
@@ -66,17 +70,26 @@ typedef struct {
     /// Pointer to the port for non-PWM pins.
     __IO uint32_t* masked_port;
   };
+  #ifdef MAX_PWM_ACTIVE
+    uint16_t max_value;
+  #endif
   uint8_t uses_pwm;
   uint8_t invert;
 } heater_definition_t;
 
+#ifdef MAX_PWM_ACTIVE
+  #define HEATER_MAX_VALUE(max_value) (max_value * 64 + 12) / 25), /* scale 100% = 256 */
+#else
+  #define HEATER_MAX_VALUE(dummy)
+#endif
 
 #undef DEFINE_HEATER
-#define DEFINE_HEATER(name, pin, invert, pwm) \
+#define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
   { \
     { pwm && pin ## _TIMER ? \
       &(pin ## _TIMER->MR[pin ## _MATCH]) : \
       &(pin ## _PORT->MASKED_ACCESS[MASK(pin ## _PIN)]) }, \
+    HEATER_MAX_VALUE(max_value) /*no comma here!*/ \
     pwm && pin ## _TIMER, \
     invert ? 1 : 0 \
   },
@@ -131,7 +144,7 @@ void heater_init() {
   */
   // Auto-generate pin setup.
   #undef DEFINE_HEATER
-  #define DEFINE_HEATER(name, pin, invert, pwm) \
+  #define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
     if (pwm && pin ## _TIMER) {                                             \
       uint32_t freq;                                                        \
                                                                             \
@@ -196,7 +209,11 @@ void heater_set(heater_t index, uint8_t value) {
       uint32_t pwm_value;
 
       // Remember, we scale, and the timer inverts already.
+      #ifdef MAX_PWM_ACTIVE
+        pwm_value = (uint32_t)((heaters[index].max_value * value) * (PWM_SCALE / 255) / 256);
+      #else
       pwm_value = (uint32_t)value * (PWM_SCALE / 255);
+      #endif
       if ( ! heaters[index].invert)
         pwm_value = PWM_SCALE - pwm_value;
       *heaters[index].match = pwm_value;
diff --git a/heater.h b/heater.h
index 92e81ca..c78af97 100644
--- a/heater.h
+++ b/heater.h
@@ -30,7 +30,7 @@
 
 
 #undef DEFINE_HEATER
-#define DEFINE_HEATER(name, pin, invert, pwm) HEATER_ ## name,
+#define DEFINE_HEATER(name, pin, invert, pwm, ...) HEATER_ ## name,
 typedef enum
 {
 	#include "config_wrapper.h"
diff --git a/testcases/board.regtest-no-endstops.h b/testcases/board.regtest-no-endstops.h
index 4e81311..6c175fc 100644
--- a/testcases/board.regtest-no-endstops.h
+++ b/testcases/board.regtest-no-endstops.h
@@ -67,8 +67,8 @@ DEFINE_TEMP_SENSOR(bed,      TT_THERMISTOR, AIO2,  THERMISTOR_BED)
   #define DEFINE_HEATER(...)
 #endif
 
-DEFINE_HEATER(extruder, DIO4,    0,      1)
-DEFINE_HEATER(bed,      DIO3,    0,      1)
+DEFINE_HEATER(extruder, DIO4,    0,      1,     100)
+DEFINE_HEATER(bed,      DIO3,    0,      1,     100)
 
 #define HEATER_EXTRUDER HEATER_extruder
 #define HEATER_BED HEATER_bed
diff --git a/testcases/config.h.Profiling b/testcases/config.h.Profiling
index 558ae70..df4f4f2 100644
--- a/testcases/config.h.Profiling
+++ b/testcases/config.h.Profiling
@@ -541,9 +541,22 @@ DEFINE_TEMP_SENSOR(bed,       TT_THERMISTOR,  AIO0,      THERMISTOR_EXTRUDER)
 */
 //#define HEATER_PIN xxxx
 
+/** \def HEATER_MAX_ACTIVE
+  Enable heater_max value.
+
+  When you have a heater which has very huge power, you can reduce it.
+  For example you have a 40W 12V heater and want to use it at 24V. At 24V
+  the heater has 120W. To reduce it again to 40W set the heater_max to 25%.
+  
+  heater_max values are allowed between 1 and 100.
+*/
+
+//DEFINE_HEATERS_START
+// #define HEATER_MAX_ACTIVE
+
 //            name      pin      invert  pwm
-DEFINE_HEATER(extruder, DIO4,    0,      1)
-DEFINE_HEATER(bed,      DIO3,    0,      1)
+DEFINE_HEATER(extruder, DIO4,    0,      1,     100)
+DEFINE_HEATER(bed,      DIO3,    0,      1,     100)
 
 /// and now because the c preprocessor isn't as smart as it could be,
 /// uncomment the ones you've listed above and comment the rest.