Optimus pro battery

hello, as I wrote in a previous post (to which you have exhaustively replied and for this I thank you very much), I use the smarthwatch only as a watch. I disable sensors, bluethoot etc. and I leave the dial always illuminated.
I went from a Galaxy Watch to a Kosper optimus pro because the kosper battery is double that of the Galaxy. so I thought I had a lot more autonomy, instead it’s the opposite, the Kosper battery drains very quickly. I think it’s an Operating System problem, Android probably consumes much more than Tizen and cancels my expectations.
Do you have any advice?
Even at the cost of losing the warranty and installing a Custom Firmware.