diff --git a/vendor/nwave/nps405-codec.yaml b/vendor/nwave/nps405-codec.yaml
index da9787eefc..56c5c8967a 100644
--- a/vendor/nwave/nps405-codec.yaml
+++ b/vendor/nwave/nps405-codec.yaml
@@ -16,7 +16,7 @@ uplinkDecoder:
     - description: User Registration
       input:
         fPort: 10
-        bytes: [0xD1, 0x1F, 0x34, 0x56, 0x78]
+        bytes: [0xD1, 0x20, 0x1F, 0x34, 0x56, 0x78]
       output:
         data:
           type: user_registration
@@ -24,6 +24,7 @@ uplinkDecoder:
           previous_state_duration: 160
           previous_state_duration_error: 4
           previous_state_duration_overflow: false
+          tag_battery_voltage: 3.2
           tag_id: '1F345678'
 
     - description: Heartbeat
diff --git a/vendor/nwave/nps405.js b/vendor/nwave/nps405.js
index 72ff35a2f1..efc8264a7c 100644
--- a/vendor/nwave/nps405.js
+++ b/vendor/nwave/nps405.js
@@ -110,8 +110,8 @@ function decodeUplink(input) {
         data.previous_state_duration_error = null;
         data.previous_state_duration_overflow = null;
       }
-
-      data.tag_id = (bytes[1] << 24 | bytes[2] << 16 | bytes[3] << 8 | bytes[4]).toString(16).toUpperCase();
+      data.tag_battery_voltage = bytes[1] * 0.1;
+      data.tag_id = (bytes[2] << 24 | bytes[3] << 16 | bytes[4] << 8 | bytes[5]).toString(16).toUpperCase();
 
       break;
   }