Ubuntu 18.04 battery life with AMD ryzen7 2700

Question

I booted Ubuntu 18.04 to my SSD in Hp probook 445 G6. The problem I have is battery life, it works roughly for 3.5-4 hours with moderate load. But official document says it will run upto 11-hours with Windows.

So I have installed tlp and put some basic configs. But still no real improvement with battery.

I havent installed any graphics drivers, still with default installed graphics. I have tried to install AMD graphics but it went horribly wrong.

Simply how can I imporve my battery life at least upto 7 hours with Ubuntu 18.04.

Spec :

AMD Ryzen 7 PRO 2700U APU Integrated Radeon Vega Graphics

Kernel : 5.3.0-40-generic

Normally I would run with 7-8 Firefox tabs (with YouTube), vscode, vlc player.

Powertop device-stat gives following:

 Usage     Device name
         17.8%        CPU use
        25098%        Display backlight
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD/ATI] Rav
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] Device
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] Device
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] Device
        100.0%        Radio device: rtw_pci
        100.0%        USB device: xHCI Host Controller
        100.0%        USB device: USB2.0 Hub
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] Device
        100.0%        PCI Device: Device 1987:5012
        100.0%        PCI Device: Realtek Semiconductor Co., Ltd. RTL8822BE
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] FCH SAT
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD/ATI] Dev
        100.0%        USB device: xHCI Host Controller
        100.0%        PCI Device: Realtek Semiconductor Co., Ltd. RTS522A PC
        100.0%        USB device: USB OPTICAL MOUSE (PIXART)
        100.0%        PCI Device: Advanced Micro Devices, Inc. [AMD] Device

I have installed powertop as suggested here, but its not autotuning.

modprobe cpufreq_stats failedLoaded 0 prior measurements Cannot load from file /var/cache/powertop/saved_parameters.powertop