diff --git a/libraries/AP_BattMonitor/AP_BattMonitor.cpp b/libraries/AP_BattMonitor/AP_BattMonitor.cpp
index 3d47989f91..941dd54a46 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor.cpp
+++ b/libraries/AP_BattMonitor/AP_BattMonitor.cpp
@@ -322,7 +322,7 @@ AP_BattMonitor::init()
     if (drivers[instance] && state[instance].var_info) {
         Type type = get_type(instance);
         if((type == Type::ANALOG_VOLTAGE_AND_CURRENT) || (type == Type::ANALOG_VOLTAGE_ONLY) ||
-            (type == Type::FuelFlow) || (type == Type::FuelLevel_PWM)) {
+            (type == Type::FuelFlow) || (type == Type::FuelLevel_PWM) || (type == Type::Sum)) {
             backend_analog_var_info[instance] = state[instance].var_info;
             AP_Param::load_object_from_eeprom(drivers[instance], backend_analog_var_info[instance]);
         }
diff --git a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
index eb610d1e80..f5584db7c7 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
+++ b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.cpp
@@ -12,6 +12,18 @@
  */
 extern const AP_HAL::HAL& hal;
 
+const AP_Param::GroupInfo AP_BattMonitor_Sum::var_info[] = {
+
+    // @Param: SUM_MASK
+    // @DisplayName: Battery Sum mask
+    // @Description: 0: sum of remaining battery monitors, If none 0 sum of specified monitors. Current will be summed and voltages averaged.
+    // @Bitmask: 0:monitor 1, 1:monitor 2, 2:monitor 3, 3:monitor 4, 4:monitor 5, 5:monitor 6, 6:monitor 7, 7:monitor 8, 8:monitor 9
+    // @User: Standard
+    AP_GROUPINFO("SUM_MASK", 1, AP_BattMonitor_Sum, _sum_mask, 0),
+
+    AP_GROUPEND
+};
+
 /// Constructor
 AP_BattMonitor_Sum::AP_BattMonitor_Sum(AP_BattMonitor &mon,
                                        AP_BattMonitor::BattMonitor_State &mon_state,
@@ -20,6 +32,8 @@ AP_BattMonitor_Sum::AP_BattMonitor_Sum(AP_BattMonitor &mon,
     AP_BattMonitor_Backend(mon, mon_state, params),
     _instance(instance)
 {
+    AP_Param::setup_object_defaults(this, var_info);
+    _state.var_info = var_info;
 }
 
 // read - read the voltage and current
@@ -31,7 +45,19 @@ AP_BattMonitor_Sum::read()
     float current_sum = 0;
     uint8_t current_count = 0;
 
-    for (uint8_t i=_instance+1; i<_mon.num_instances(); i++) {
+    for (uint8_t i=0; i<_mon.num_instances(); i++) {
+        if (i == _instance) {
+            // never include self
+            continue;
+        }
+        if ((_sum_mask == 0) && (i <= _instance)) {
+            // sum of remaining, skip lower instances
+            continue;
+        }
+        if ((_sum_mask != 0) && ((_sum_mask & 1U<<i) == 0)) {
+            // mask param, skip if mask bit not set
+            continue;
+        }
         if (!_mon.healthy(i)) {
             continue;
         }
diff --git a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.h b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.h
index 56ef33c9dc..1ce91ed636 100644
--- a/libraries/AP_BattMonitor/AP_BattMonitor_Sum.h
+++ b/libraries/AP_BattMonitor/AP_BattMonitor_Sum.h
@@ -21,7 +21,11 @@ public:
 
     void init(void) override {}
 
+    static const struct AP_Param::GroupInfo var_info[];
+
 private:
+
+    AP_Int16  _sum_mask;
     uint8_t _instance;
     bool _has_current;
 };