Contents:

The battery is in the trunk under the compartment cover.
When replacing the battery, disconnect the negative (-) cable (1) and remove the positive (+) battery fuse box (2).
Remove the battery mounting bracket (3).
WARNING - Touching metal surfaces in the trunk under the compartment cover

Do not touch metal surfaces in the trunk under the compartment cover while the engine is operating or hot. Doing so could result in serious personal injury. Turn the engine off and wait until it cools down or wear gloves to replace the battery from the luggage room.
Your vehicle has a maintenance-free, calcium-based battery.
When recharging the battery, observe the following precautions:
Reset items
Items should be reset after the battery has been discharged or the battery has been disconnected.
Kia Stinger (CK) 2018-2023 Owner's Manual: Tail Gate Assembly
Components and components location Components Location 1. Tailgate assembly Repair procedures Replacement Wear gloves to protect hands from injury. When removing and installing the tail gate, an assistant is needed.Specifications Specification ▷ 13.5V, 150A Item Specification Rated voltage 13.5V , 150A Speed in use 0 - 18,000 rpm Pin 1 Voltage regulator IC Regulator built in type Default regulated voltage (V) [COM terminal] 14.