diff --git a/libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp b/libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp
index 0eb859d2a4..486634ce57 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp
+++ b/libraries/AP_BattMonitor/AP_BattMonitor_Params.cpp
@@ -150,7 +150,7 @@ const AP_Param::GroupInfo AP_BattMonitor_Params::var_info[] = {
     // @Param: OPTIONS
     // @DisplayName: Battery monitor options
     // @Description: This sets options to change the behaviour of the battery monitor
-    // @Bitmask: 0:Ignore DroneCAN SoC, 1:MPPT reports input voltage and current, 2:MPPT Powered off when disarmed, 3:MPPT Powered on when armed, 4:MPPT Powered off at boot, 5:MPPT Powered on at boot, 6:Send resistance compensated voltage to GCS, 7:Allow DroneCAN InfoAux to be from a different CAN node
+    // @Bitmask: 0:Ignore DroneCAN SoC, 1:MPPT reports input voltage and current, 2:MPPT Powered off when disarmed, 3:MPPT Powered on when armed, 4:MPPT Powered off at boot, 5:MPPT Powered on at boot, 6:Send resistance compensated voltage to GCS, 7:Allow DroneCAN InfoAux to be from a different CAN node, 9:Sum monitor measures minimum voltage instead of average
     // @User: Advanced
     AP_GROUPINFO("OPTIONS", 21, AP_BattMonitor_Params, _options, 0),
 #endif // HAL_BUILD_AP_PERIPH
diff --git a/libraries/AP_BattMonitor/AP_BattMonitor_Params.h b/libraries/AP_BattMonitor/AP_BattMonitor_Params.h
index 2088845c39..4665e0eeaa 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor_Params.h
+++ b/libraries/AP_BattMonitor/AP_BattMonitor_Params.h
@@ -17,7 +17,7 @@ class AP_BattMonitor_Params {
         BattMonitor_LowVoltageSource_Raw            = 0,
         BattMonitor_LowVoltageSource_SagCompensated = 1
     };
-    enum class Options : uint8_t {
+    enum class Options : uint16_t {
         Ignore_UAVCAN_SoC                   = (1U<<0),  // Ignore UAVCAN State-of-Charge (charge %) supplied value from the device and use the internally calculated one
         MPPT_Use_Input_Value                = (1U<<1),  // MPPT reports voltage and current from Input (usually solar panel) instead of the output
         MPPT_Power_Off_At_Disarm            = (1U<<2),  // MPPT Disabled when vehicle is disarmed, if HW supports it
@@ -26,6 +26,8 @@ class AP_BattMonitor_Params {
         MPPT_Power_On_At_Boot               = (1U<<5),  // MPPT Enabled at startup (aka boot), if HW supports it. If Power_Off_at_Boot is also set, the behavior is Power_Off_at_Boot
         GCS_Resting_Voltage                 = (1U<<6),  // send resistance resting voltage to GCS
         AllowSplitAuxInfo                   = (1U<<7),  // allow different node to provide aux info for DroneCAN
+        InternalUseOnly                     = (1U<<8),  // for use internally to ArduPilot, not to be (eg.) sent via MAVLink BATTERY_STATUS
+        Minimum_Voltage                     = (1U<<9),  // sum monitor measures minimum voltage rather than average
     };
 
     BattMonitor_LowVoltage_Source failsafe_voltage_source(void) const { return (enum BattMonitor_LowVoltage_Source)_failsafe_voltage_source.get(); }
diff --git a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
index 2a7401d326..ff19204976 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
+++ b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
@@ -50,10 +50,14 @@ void
 AP_BattMonitor_Sum::read()
 {
     float voltage_sum = 0;
+    float voltage_min = 0;
     uint8_t voltage_count = 0;
     float current_sum = 0;
     uint8_t current_count = 0;
 
+    float consumed_mah_sum = 0;
+    float consumed_wh_sum = 0;
+
     for (uint8_t i=0; i<_mon.num_instances(); i++) {
         if (i == _instance) {
             // never include self
@@ -70,26 +74,43 @@ AP_BattMonitor_Sum::read()
         if (!_mon.healthy(i)) {
             continue;
         }
-        voltage_sum += _mon.voltage(i);
+        const float voltage = _mon.voltage(i);
+        if (voltage_count == 0 || voltage < voltage_min) {
+            voltage_min = voltage;
+        }
+        voltage_sum += voltage;
         voltage_count++;
         float current;
         if (_mon.current_amps(current, i)) {
             current_sum += current;
             current_count++;
         }
+
+        float consumed_mah;
+        if (_mon.consumed_mah(consumed_mah, i)) {
+            consumed_mah_sum += consumed_mah;
+        }
+
+        float consumed_wh;
+        if (_mon.consumed_wh(consumed_wh, i)) {
+            consumed_wh_sum += consumed_wh;
+        }
     }
     const uint32_t tnow_us = AP_HAL::micros();
-    const uint32_t dt_us = tnow_us - _state.last_time_micros;
 
     if (voltage_count > 0) {
-        _state.voltage = voltage_sum / voltage_count;
+        if (option_is_set(AP_BattMonitor_Params::Options::Minimum_Voltage)) {
+            _state.voltage = voltage_min;
+        } else {
+            _state.voltage = voltage_sum / voltage_count;
+        }
     }
     if (current_count > 0) {
         _state.current_amps = current_sum;
+        _state.consumed_mah = consumed_mah_sum;
+        _state.consumed_wh = consumed_wh_sum;
     }
 
-    update_consumed(_state, dt_us);
-
     _has_current = (current_count > 0);
     _state.healthy = (voltage_count > 0);