diff --git a/content/pybytes/api/_index.md b/content/pybytes/api/_index.md
index 62f088a..8943490 100644
--- a/content/pybytes/api/_index.md
+++ b/content/pybytes/api/_index.md
@@ -4,7 +4,7 @@ aliases:
 ---
 
 
-The Pybytes library is positioned in the [frozen](/advance/frozen/) section of the firmware. 
+The Pybytes library is positioned in the [frozen](/advance/frozen/) section of the firmware.
 
 It can be imported like regular modules:
 ```python
@@ -63,7 +63,7 @@ Connect the device to Pybytes following the loaded configuration file. You will
 
 ### pybytes.start([autoconnect=True])
 
-Same as `pybytes.connect()`, with the option to set `autoconnect`. Setting `autoconnect` to `False` will not start the connection immediately. 
+Same as `pybytes.connect()`, with the option to set `autoconnect`. Setting `autoconnect` to `False` will not start the connection immediately.
 
 ### pybytes.enable_lte(carrier=None, cid=None, band=None, apn=None, type=None, reset=None, fallback=False)
 
@@ -127,7 +127,7 @@ Send a signal to Pybytes. Arguments are:
 
 ### pybytes.send_ping_message()
 
-Sends a ping (is-alive) message to Pybytes. 
+Sends a ping (is-alive) message to Pybytes.
 
 ### pybytes.send_info_message()
 
@@ -135,7 +135,22 @@ Send an info message to Pybytes containing the device type and firmware version.
 
 ### pybytes.send_battery_level(battery_level)
 
-Sends the battery level to Pybytes. The argument `battery_level` can be any integer.
+Sends the battery level to **[Pybytes](https://pybytes.pycom.io/)**. The argument `battery_level` can be any integer.
+
+You can define `battery_level` with a function depending on your shield. Check example code by visiting [Reading Battery Voltage page](/tutorials/expansionboards/vbat).
+
+For example, using an Expansion Board 3.1, you can send battery level to **[Pybytes](https://pybytes.pycom.io/)** using the below code:
+
+```python
+from machine import ADC
+def battery_level():
+    adc = ADC()
+    bat_voltage = adc.channel(attn=ADC.ATTN_11DB, pin='P16')
+    vbat = bat_voltage.voltage()
+    print('battery voltage:', vbat*2, 'mV')
+    return vbat*2
+pybytes.send_battery_level(battery_level())
+```
 
 ## Miscellaneous
 
@@ -164,4 +179,3 @@ There are multiple debug levels, the lowest is 0 which is for warnings only and
 >> import pycom;
 >> pycom.nvs_set('pybytes_debug', 99)
 ```    
-