diff --git a/msg/versioned/BatteryStatus.msg b/msg/versioned/BatteryStatus.msg
index 47bcf0f3ed..5eefb41c52 100644
--- a/msg/versioned/BatteryStatus.msg
+++ b/msg/versioned/BatteryStatus.msg
@@ -65,9 +65,9 @@ uint8 FAULT_FAILED_TO_ARM = 10 # Battery had a problem while arming
 uint8 FAULT_COUNT = 11 # Counter. Keep this as last element
 
 float32 full_charge_capacity_wh # [Wh] Compensated battery capacity
-float32 remaining_capacity_wh # [Wh] Compensated battery capacity remaining
+float32 remaining_capacity_wh # [Wh] [@invalid NaN] Compensated battery capacity remaining
 uint16 over_discharge_count # [-] Number of battery overdischarge
-float32 nominal_voltage # [V] Nominal voltage of the battery pack
+float32 nominal_voltage # [V] [@invalid NaN] Nominal voltage of the battery pack
 
 float32 internal_resistance_estimate # [Ohm] Internal resistance per cell estimate
 float32 ocv_estimate # [V] Open circuit voltage estimate
diff --git a/src/drivers/uavcan/sensors/battery.cpp b/src/drivers/uavcan/sensors/battery.cpp
index d62d43dfb2..8dfff769c5 100644
--- a/src/drivers/uavcan/sensors/battery.cpp
+++ b/src/drivers/uavcan/sensors/battery.cpp
@@ -184,7 +184,8 @@ UavcanBatteryBridge::battery_aux_sub_cb(const uavcan::ReceivedDataStructure<ardu
 	_battery_status[instance].cell_count = math::min((uint8_t)msg.voltage_cell.size(), (uint8_t)14);
 	_battery_status[instance].cycle_count = msg.cycle_count;
 	_battery_status[instance].over_discharge_count = msg.over_discharge_count;
-	_battery_status[instance].nominal_voltage = msg.nominal_voltage;
+	// ArduPilot BatteryInfoAux convention: nominal_voltage == 0 means "not provided"
+	_battery_status[instance].nominal_voltage = (msg.nominal_voltage > FLT_EPSILON) ? msg.nominal_voltage : NAN;
 	_battery_status[instance].is_powering_off = msg.is_powering_off;
 
 	if (msg.nominal_voltage > FLT_EPSILON) {
diff --git a/src/lib/battery/battery.cpp b/src/lib/battery/battery.cpp
index 95b1c3109f..766c147e61 100644
--- a/src/lib/battery/battery.cpp
+++ b/src/lib/battery/battery.cpp
@@ -184,6 +184,8 @@ battery_status_s Battery::getBatteryStatus()
 	battery_status.warning = _warning;
 	battery_status.timestamp = hrt_absolute_time();
 	battery_status.faults = determineFaults();
+	battery_status.remaining_capacity_wh = NAN; // not measured by dumb power module; smart-battery drivers overwrite
+	battery_status.nominal_voltage = NAN;        // not measured by dumb power module; smart-battery drivers overwrite
 	battery_status.internal_resistance_estimate = _internal_resistance_estimate;
 	battery_status.ocv_estimate = _voltage_v + _internal_resistance_estimate * _params.n_cells * _current_a;
 	battery_status.ocv_estimate_filtered = _ocv_filter_v.getState();