Page 563 of the online guide clearly states: (as does the UK version of the guide)
The High Voltage battery gradually discharges even if the vehicle is not in use. As a result, if your vehicle is parked for an extended period of time, the battery level may get low. Keeping your vehicle’s battery level low can shorten the battery life, negatively affecting the vehicle’s range. To maintain the battery while the vehicle is not in use, recharge the battery at least once every three months. The High Voltage battery life can also be affected by ambient temperature. In particular, when it is cold outside, the vehicle’s driving range can be reduced, and a longer battery charging time is required. In addition, parking in extremely hot or cold environments can accelerate battery drain. To help extend the lifespan of the battery, it is recommended that you fully charge the battery each time prior to driving.
I see you in NZ not UK some differences with the manual/Guide.
Regards