fix(gateway): bind battery_scaling, battery_rate_max and inverter_time per inverter

apps/predbat/gateway.py

@@ -1291,6 +1291,9 @@ def automatic_config(self):
         discharge_enable_entities = []
         export_limit_entities = []
         inverter_limit_entities = []
+        battery_scaling_entities = []
+        battery_rate_max_entities = []
+        inverter_time_entities = []
 
         for inv in inverters:
             suffix = inv.serial[-6:].lower()
@@ -1323,6 +1326,10 @@ def automatic_config(self):
                 self.log(f"Warn: GatewayMQTT: inverter {inv.serial} has no battery capacity, setting to None for automatic discovery")
 
             inverter_limit_entities.append(f"sensor.{base}_inverter_rate_max")
+            battery_scaling_entities.append(f"sensor.{base}_battery_dod")
+            battery_rate_max_entities.append(f"sensor.{base}_battery_rate_max")
+            # Clock drift detection — uses GatewayStatus.timestamp
+            inverter_time_entities.append(f"sensor.{base}_inverter_time")
 
         # Map entity lists to PredBat args
         self.set_arg("soc_percent", soc_entities)
@@ -1355,13 +1362,11 @@ def automatic_config(self):
 
         # Battery health (first inverter)
         self.set_arg("battery_temperature_history", f"sensor.{base0}_battery_temperature")
-        self.set_arg("battery_scaling", [f"sensor.{base0}_battery_dod"])
 
-        # Battery rate max
-        self.set_arg("battery_rate_max", [f"sensor.{base0}_battery_rate_max"])
-
-        # Inverter time (clock drift detection — uses GatewayStatus.timestamp)
-        self.set_arg("inverter_time", [f"sensor.{base0}_inverter_time"])
+        # Per-inverter: inverter.py reads these at index=self.id, so each needs one entry per inverter
+        self.set_arg("battery_scaling", battery_scaling_entities)
+        self.set_arg("battery_rate_max", battery_rate_max_entities)
+        self.set_arg("inverter_time", inverter_time_entities)
 
         # EMS aggregate entities (GivEnergy EMS only)
         inv0 = inverters[0]

apps/predbat/tests/test_gateway.py

@@ -1746,6 +1746,28 @@ def test_multi_inverter_produces_multiple_entity_lists(self):
         assert "000aa1" in gw._args["soc_percent"][0]
         assert "000bb2" in gw._args["soc_percent"][1]
 
+    def test_multi_inverter_battery_args_have_one_entry_per_inverter(self):
+        """battery_scaling, battery_rate_max and inverter_time are per-inverter args, so each gets one entry per primary inverter.
+
+        A single entry leaves inverter 1 reading index 1 out of range: PredBat falls back to a 2600 W battery_rate_max
+        and 1.0 battery_scaling, and never checks that inverter's clock.
+        """
+        gw = self._make_gateway()
+        status = pb.GatewayStatus()
+        status.device_id = "pbgw_multi"
+        status.firmware = "1.0.0"
+        status.schema_version = 1
+        self._make_inverter(status, serial="CE2223G800", primary=True)
+        self._make_inverter(status, serial="CE2225G400", primary=True)
+        gw._last_status = status
+        gw.automatic_config()
+
+        base0 = f"{gw.prefix}_gateway_23g800"
+        base1 = f"{gw.prefix}_gateway_25g400"
+        assert gw._args["battery_scaling"] == [f"sensor.{base0}_battery_dod", f"sensor.{base1}_battery_dod"]
+        assert gw._args["battery_rate_max"] == [f"sensor.{base0}_battery_rate_max", f"sensor.{base1}_battery_rate_max"]
+        assert gw._args["inverter_time"] == [f"sensor.{base0}_inverter_time", f"sensor.{base1}_inverter_time"]
+
     # ------------------------------------------------------------------
     # Secondary (cloud) and unsupported feature args
     # ------------------------------------------------------------------