The battery is between 900mah and 1100mah as you can see in Lem14 (same watch and hardware) support thread.
If you are determined to use always on display - I believe that the universal launcher from @Eric_Crochemore (here on the forum) supports it.
You just need to ensure that it is set as the default launcher and all permissions are set correctly.
But it will eat the battery power very much faster than the stock setting for the screen.
These devices are just not designed to be used this way.
It is a shame that you didn’t find this site before you purchased…
This model is likely not very suitable for your requirements… Especially with the low spec battery and TFT screen.
But you can try the UL and also disable as many of the apps (that you don’t need) as possible to save power.
Sadly, the advertising for this model is very false about the specifications…
So much so that I ended up having a massive argument with the manufacturer about false advertising.
Lemfo then corrected the LEM14 advertising but Rogbid did not.
The “actual” real specs can be read about here. Also, please do not trust the ridiculous waterproof claim…
We have had a few people who did, and ended up with a dead watch. You can also find this information in the LEM14 section here.