Huawei FC8021 User Guide - Page 16

 Keep the ambient temperature between 0°C and 45°C while the device is being charged. Keep the ambient temperature between -10°C to 55°C for using the device powered by a battery. Safety of Children Comply with all precautions with regard to children's safety. Letting the child play with your device or its accessories, which may include parts that can be detached from the device, may be dangerous, as it may present a choking hazard. Ensure that small children are kept away from the device and accessories. Accessories Use the accessories delivered only by the manufacturer. Using accessories of other manufacturers or vendors with this device model may invalidate any approval or warranty applicable to the device, result in the non-operation of the device, and cause danger. Battery and Charger  Unplug the charger from the electrical plug and the device when not in use.  The battery can be charged and discharged hundreds of times before it eventually wears out. When the standby time and the talk time are shorter than the normal time, replace the battery.  Use the AC power supply defined in the specifications of the charger. An improper power voltage may cause a fire or a malfunction of the charger.  Do not connect two poles of the battery with conductors, such as metal materials, keys, or jewelries. Otherwise, the battery may be short-circuited and may cause injuries and burns on your body. 14