diff --git a/include/defines.h b/include/defines.h
index bf42e2e..2701c4f 100644
--- a/include/defines.h
+++ b/include/defines.h
@@ -41,6 +41,6 @@
 #define servoLEDCChannel LEDC_CHANNEL_0
 #define servoSwitch GPIO_NUM_17
 
-#define debugLED GPIO_NUM_22 // d4
+#define debugLED GPIO_NUM_18 // d10
 
 #endif
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 93031fc..396b5d9 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -56,5 +56,5 @@ void pm_init() {
 extern "C" void app_main() {
   // pm_init();
   // mainApp();
-  bms_test_app();
+  bms_test_LED();
 }
\ No newline at end of file
diff --git a/test/bms_test.cpp b/test/bms_test.cpp
index fddc45c..ffdb2a6 100644
--- a/test/bms_test.cpp
+++ b/test/bms_test.cpp
@@ -1,8 +1,55 @@
 #include "bms_test.hpp"
 #include "i2c.h"
 #include "max17048.h"
+#include "defines.h"
 
-void bms_test_app() {
+void bms_test_LED() {
+  vTaskDelay(pdMS_TO_TICKS(5000));
+  i2c_init();
+
+  gpio_config_t led_conf = {
+    .pin_bit_mask = (1ULL << debugLED),
+    .mode         = GPIO_MODE_OUTPUT,
+    .pull_up_en   = GPIO_PULLUP_DISABLE,
+    .pull_down_en = GPIO_PULLDOWN_DISABLE,
+    .intr_type    = GPIO_INTR_DISABLE,
+  };
+  gpio_config(&led_conf);
+
+  bms_set_alert_bound_voltages(3.8f, 3.9f);
+  bms_clear_status();
+  bms_clear_alrt();
+
+  while (true) {
+    uint8_t msb, lsb;
+    if (max17048_read_reg(MAX17048_REG_STATUS, &msb, &lsb) == ESP_OK) {
+      bool vh = !!(msb & VHbit);
+      bool vl = !!(msb & VLbit);
+
+      bms_clear_status();
+      bms_clear_alrt();
+      if (vl) {
+        // Under-voltage: LED off
+        gpio_set_level(debugLED, 0);
+        vTaskDelay(pdMS_TO_TICKS(1000));
+      } else if (vh) {
+        // Over-voltage: rapid blink
+        gpio_set_level(debugLED, 1);
+        vTaskDelay(pdMS_TO_TICKS(100));
+        gpio_set_level(debugLED, 0);
+        vTaskDelay(pdMS_TO_TICKS(100));
+      } else {
+        // Normal: LED on
+        gpio_set_level(debugLED, 1);
+        vTaskDelay(pdMS_TO_TICKS(1000));
+      }
+    } else {
+      vTaskDelay(pdMS_TO_TICKS(1000));
+    }
+  }
+}
+
+void bms_test() {
   vTaskDelay(pdMS_TO_TICKS(5000));
   esp_err_t err = i2c_init();
 
diff --git a/test/bms_test.hpp b/test/bms_test.hpp
index 2553ddc..ee93ecb 100644
--- a/test/bms_test.hpp
+++ b/test/bms_test.hpp
@@ -1,6 +1,7 @@
 #ifndef BMS_TEST_H
 #define BMS_TEST_H
 
-void bms_test_app();
+void bms_test();
+void bms_test_LED();
 
 #endif
\ No newline at end of file