diff --git a/esphome/esp-bedside-panel.yaml b/esphome/esp-bedside-panel.yaml
index 660f2fe..b98ef17 100644
--- a/esphome/esp-bedside-panel.yaml
+++ b/esphome/esp-bedside-panel.yaml
@@ -6,6 +6,7 @@
 # https://home.fox.co.nz/gitea/zorruno/zorruno-homeassistant/src/branch/master/esphome/esp-bedside-panel.yaml
 #:########################################################################################:#
 # VERSIONS:
+# V1.48 2026-07-28 Added raw onboard battery ADC voltage monitoring on GPIO53 for divider calibration
 # V1.47 2026-07-20 Widened the alarm volume range while retaining 5-100% controls and the proven 6000 Hz tone
 # V1.46 2026-07-20 Raised the alarm tone to 6000 Hz, limited volume to 5-100%, and remapped 100% to the previous displayed 30% level
 # V1.45 2026-07-20 Shortened the project description to remain within ESPHome's 255-byte string limit
@@ -107,6 +108,7 @@
 # - Battery-backed RTC: RX8130
 # - RTC I2C address: 0x32
 # - TEMT6000 ambient-light sensor signal: GPIO20 / ADC1
+# - Battery voltage sense test input: GPIO53 / ADC2
 # - ES8311 audio codec: I2C address 0x18
 # - Audio I2S: MCLK GPIO13, BCLK GPIO12, LRCLK GPIO10, DOUT GPIO9
 # - Speaker amplifier enable: GPIO11 (active high on this board revision)
@@ -156,6 +158,8 @@
 # - Beep is a short 6000 Hz electronic tone.
 # - Alarm repeats a quick 6000 Hz beep-beep-beep group followed by a pause.
 # - Speaker tests generate audio locally and do not require Home Assistant or media files.
+# - Raw battery-sense ADC voltage is exposed from GPIO53 for calibration.
+# - No battery divider multiplier or percentage estimate is applied in this test version.
 #:########################################################################################:#
 # OFFLINE NOTES:
 # - LVGL, the clock, touch and backlight operate locally.
@@ -174,12 +178,12 @@ substitutions:
   # Device Naming
   device_name: "esp-bedside-panel"
   friendly_name: "ESP Bedside Panel"
-  description_comment: "Guition JC1060P470C_I_W_Y ESP32-P4 bedside panel with four alarms, 6000 Hz triplet sound, wide 5-100% volume range and 24-hour time editor. (Layout V1.1)"
+  description_comment: "Guition JC1060P470C_I_W_Y ESP32-P4 bedside panel with four alarms, local speaker tests, battery ADC monitoring and a 24-hour time editor. (Layout V1.1)"
   device_area: "Bedroom"
 
   # Project Naming
   project_name: "Guition.JC1060P470C_I_W_Y"
-  project_version: "v1.47"
+  project_version: "v1.48"
 
   # Passwords & Secrets
   api_key: !secret esp-api_key
@@ -199,6 +203,12 @@ substitutions:
   ambient_light_pin: "GPIO20"
   ambient_light_update_interval: "1s"
 
+  # Battery Voltage Test Settings
+  # GPIO53 is connected to the board battery-sense circuit. The raw ADC
+  # voltage is published first so the onboard divider can be calibrated.
+  battery_voltage_pin: "GPIO53"
+  battery_voltage_update_interval: "5s"
+
   # Touchscreen Settings
   touch_sda_pin: "GPIO7"
   touch_scl_pin: "GPIO8"
@@ -1097,6 +1107,37 @@ sensor:
     id: wifi_signal_sensor
     update_interval: "${update_interval}"
 
+  #:######################################################################################:#
+  # INTERNAL BATTERY ADC VOLTAGE                                                         #
+  #:######################################################################################:#
+  #
+  # GPIO53 is connected to the JC1060P470 battery-sense circuit.
+  #
+  # This sensor intentionally reports the raw voltage present at the ADC pin.
+  # Do not treat it as the actual 18650 voltage until it has been compared with
+  # a multimeter and the board's voltage-divider ratio has been established.
+  #
+  # The ADC samples every five seconds. A rolling median is published every
+  # third sample, giving a new filtered value approximately every 15 seconds.
+
+  - platform: adc
+    id: battery_adc_voltage
+    name: "${friendly_name} Battery ADC Voltage"
+    pin: "${battery_voltage_pin}"
+    attenuation: auto
+    update_interval: "${battery_voltage_update_interval}"
+    accuracy_decimals: 3
+    device_class: voltage
+    state_class: measurement
+    unit_of_measurement: "V"
+    icon: mdi:battery
+    entity_category: diagnostic
+    filters:
+      - median:
+          window_size: 5
+          send_every: 3
+          send_first_at: 1
+
   #:######################################################################################:#
   # TEMT6000 AMBIENT LIGHT SENSOR
   #:######################################################################################:#
@@ -11861,4 +11902,4 @@ lvgl:
             text: ""
             text_font: font_small
             text_color: 0x887799
-            clickable: false
+            clickable: false
\ No newline at end of file