supplementary charging

例句：

1. 1. The smartphone hasa built-in 5000mAh battery that can be charged using a USB cable.
   这款智能手机内置了一块5000mAh的电池，可以通过USB线进行充电。
2. 2. To extend the battery life of your laptop, consider investing in a supplementary battery charger.
   为了延长笔记本电脑的电池寿命，可以考虑投资购买一个补充电池充电器。
3. 3. During long flights, it's important to have a backup power source for supplementary charging.
   在长时间的飞行中，备用电源对于补充充电非常重要。