# Battery life of Bangle J.s - in real world situations

• Thr 2021.03.18

'The Bangle.Js looks like it could be fun'

YES @user126405 the Bangle and all the Espruino original boards are fun to tinker with!

'How long does it last in normal usage?'

Simple explanation for battery ampacity

https://learn.sparkfun.com/tutorials/how­-to-power-a-project/remotemobile-power

I found the specific answer for Bangle by taking a peek at the Bangle presentation page:

http://www.espruino.com/Bangle.js

Idle, accelerometer on 1.25Hz - 0.15mA (default if not moved)
GPS on - 30mA

From there I searched to the bottom of the page at the tutorial icons and selected 'Technical Information'

http://www.espruino.com/Bangle.js+Techni­cal

350mAh battery, 1 week standby time

How to calculate from those values? Total capacity 350mA or 0.350A

At idle, 0.15mA or 0.000 150A are consumed when there is no movement. When GPS is
enabled, 30mA or 0.030 000A are consumed. Using simple division, `Total Capacity / Draw` will provide the time in milliampere-hours. Dividing that by the number of hours in a day, yields the expected number of days.

``````// * Idle *

Total capacity 0.350 000A   /   0.000 150A = 2333 hrs

2333 / 24 = 97 days

``````

Note that individual mileage may vary

``````// * GPS When full on *

Total capacity 0.350A   /   0.030A = 11.67 hrs

``````

Through your specific coding technique, GPS could be turned on and off to extend that value

'Both with and without GPS (if that can be turned off)'

Also take a look at this ongoing discussion within thread:

Bangle GPS Power management

Post #21 Bar Graph