Bangle.js2. How to get 1 month battery life? (instead a few days only)

So, the bangle.js2 should allow about 1 month battery life? How to get that, while still actually using the watch?
My battery loses about 10% per day, so I am far away from one month of battery life.
How to find out what's causing this? Or maybe my battery is broken and just doesn't have the expected capacity?
And during the first days the battery lasted one day only. I was using a clock face with one refresh per second and maybe GPS was turned on, too.
Now GPS is off, Compass is off, Heart rate is once every 3 Minutes. Clock face refreshes every minute. "Turn on on touch" is turned off.

See this question in the wiki:
https://github.com/espruino/BangleApps/wiki

There is also a power monitoring app that will show you how much power is being used and writes to a log. But the answer in the wiki covers most of the big power drainers.

I used to only get 3 days as I was constantly flashing new versions of code onto the watch. But I have eased off developing so much and most often get 2 weeks. This drops to about 1 week to 10 days if I start using the heart rate monitor with a setting of 3 mins. I definitely would say set heart rate to every 10 minutes or off. If you use a clock that supports clock_info you can always tap the heart rate clock_info to get a refresh.

I think I get about 20+ days on my 2nd Bangle2 which has HRM off and just stays mostly in a drawer.

What clock face are you using? Those can have quite a big effect - for instance Slope Clock which updates once a minute still uses quite a bit of power because it's animated.

In order of power consumption (there are some figures at https://www.espruino.com/Bangle.js2#power-consumption):

• GPS
  
• LCD backlight
  
• Compass
  
• Heart rate
  
• Bluetooth connection
  
  

GPS is a massive power draw, so yes, if you have it on the battery will flatten quickly - there's not really a way around that.

So to get the absolute best battery life, you want:

• A non-animated clock that updates once a minute
  
• 'Wake on twist' turned off
  
• Ideally no (or 10 minute) heart rate sensing
  
  

I have a bunch of watches here that I use for development, and for the ones sitting on the desk (especially if they just have the factory apps on) I reckon I must get almost 2 months