Battery drains super fast (45 minutes, without periherals, idle)

[Jozo544]

Hello, I have a problem with PiJuice and Raspberry Pi 3B. I have fresh RPI and I SSH to it. My battery is LiPo 3.7V/8000mAh and I tried how long the RPI can last on it while switched on (idle) without any other peripherals (only Pijuice+battery and RPI 3B). My result was 45 minutes (it went from 99% to 14% then crashed) and i think it is weird. Did i messed up something in configuration of PiJuice or do i need to underclock RPI or make other changes to save power?
I am doing project with modular sensoric station where RPI will measure whole day, but with sleeps between measurement cycles and under load it will be much worse. On the start i even had problem when i connected all periherals that RPI did not even wanted to boot - it was stuck in cycle where it started booting but crashed and stared booting again - probably because of power spikes and now I am stating to doubt if my project is even possible.
Thanks for all replys.

Battery settings:
Custom
Chemistry: LIPO
Capacity [mAh]: 8000
Charge current [mA]: 2500
Termination current [mA]: 150
Regulation voltage [mV]: 4180
Cutoff voltage [mV]: 2800
Cold temperature [C]: 0
Cool temperature [C]: 2
Warm temperature [C]: 49
Hot temperature [C]: 65
NTC B constant [1k]: 3450
NTC resistance [ohm]: 10000
OCV10 [mV]: 3506
OCV50 [mV]: 3870
OCV90 [mV]: 4056
R10 [mOhm]: 111.0
R50 [mOhm]: 105.0
R90 [mOhm]: 107.0

Temperature sense: ON_BOARD
Rsoc estimation: AUTO_DETECT