Ok, so today I starting new listening session and only after about 20 seconds I hearing again "battery low" message and 6% battery remaining, same percentage like end of session last night.
After 1 hr and 5 mins I hear "battery low" message again and immediately after this the headphone is switching off with 5% remaining (I see the percentage 5 mins before this). I try turning on again, and I hear is sound that is connecting but is disconnection again immediately.
So, I getting in total of 44 hrs and 12 mins with my use (95% with no ANC or transparency on and volume with average of 55%).
So, the first "battery low" message is when is 9%, the second is after 2 hrs when is 6%, then after 1 hr (at 5%) new same message but headphone dying immediately.
So, my suggestion is that, if you aren't paying attention to battery levels, start charging after first or second message. But I personally always recharging after about 30% battery remaining because I don't like my devices having very low battery levels.