diff --git a/gateway/include/devices.h b/gateway/include/devices.h
index ef1ed16..984135d 100644
--- a/gateway/include/devices.h
+++ b/gateway/include/devices.h
@@ -52,7 +52,7 @@ Sensor* buildTankSensor(const char* id) {
             .build()
         )
         .addDiagnostic(new VoltageSensor{id, "Battery voltage", "{{ value_json.sensor.diagnostic.voltage }}"})
-        .addDiagnostic(new BatterySensor{id, "Battery level", "{{ ((value_json.sensor.diagnostic.voltage|float-4.8)|round(2)*100/1.6)|int }}"})
+        .addDiagnostic(new BatterySensor{id, "Battery level", "{{ ((value_json.sensor.diagnostic.voltage|float-4.0)|round(2)*100/2.4)|int }}"})
         .build();
 }