your battery tray is find, mine does that also. how long is it lasting before it dies? i’m using samsung 35Es and i get about 3-5 hours with a cm5 and 5-6 with a cm4.
the battery capacity is set but you can change it with this overlay. clockworkpi-custom-battery.dtbo
to use the overlay, in you config.txt add this line and edit to your needs.
dtoverlay=clockworkpi-custom-battery,charge_full_design_uah=<full charge in uAh>,energy_full_design_uwh=<full charge in uWh>
remove the <> in the config.