Add option for custom battery path
diff --git a/Android.mk b/Android.mk
index 57bab35..199aba4 100644
--- a/Android.mk
+++ b/Android.mk
@@ -234,6 +234,9 @@
 ifneq ($(TW_MAX_BRIGHTNESS),)
 	LOCAL_CFLAGS += -DTW_MAX_BRIGHTNESS=$(TW_MAX_BRIGHTNESS)
 endif
+ifneq ($(TW_CUSTOM_BATTERY_PATH),)
+	LOCAL_CFLAGS += -DTW_CUSTOM_BATTERY_PATH=$(TW_CUSTOM_BATTERY_PATH)
+endif
 ifeq ($(TARGET_BOARD_PLATFORM),rk30xx)
     LOCAL_CFLAGS += -DRK3066
 endif