A CPR chest compression system includes a retention structure that retains the body of a patient, and a motor and a compressor that can perform CPR compressions to the chest of the patient. The motor is powered by a battery that is located on the retention structure but away from the motor, and is electrically connected to the motor via one or more wires. Accordingly the weight and volume of the battery can be located away from a top portion of the retention structure. This renders the CPR system is less heavy at the top, and therefore less likely to tilt and start compressing the chest at a different point. Moreover, this permits X-Rays of a larger footprint to go through the CPR system and reach the patient, in example configurations where the components are transparent to X-Rays.