没电了。

Use it as a standalone sentence or after a noun. If your phone dies, just point at it and say 手机没电了. If you are in a taxi and your phone is dying, tell the driver 没电了. You don't need fancy grammar here. It works like a charm in almost any sentence structure. You can also use it for electric bikes or cars.

You will use this constantly in daily life. Use it when your phone hits 1% at a restaurant. Use it when your laptop dies during a coffee shop study session. It is perfect for explaining why you didn't reply to a text. It is also a great 'exit strategy' for awkward phone calls. Just say 手机快没电了 (My phone is about to die) and hang up!

Don't use this for things that don't use electricity. If your car runs out of gas, use 没油了 instead. Also, avoid using it in extremely formal speeches. In a high-stakes board meeting, you might say something more precise. However, even then, people will understand you perfectly. It is rarely 'wrong', just very casual.

China is a mobile-first society. Everything happens on your phone—paying, eating, and traveling. Because of this, 没电了 is a high-stress phrase! You will see 'Power Bank' (充电宝) stations everywhere in Chinese malls. This phrase is the reason those businesses exist. It is the modern equivalent of saying 'I am lost'.

You can add 快 (kuài) to say 'almost out of battery'. Say 快没电了 when you see that red battery bar. If you want to ask for a charger, follow it with 有充电器吗?. You can also use it metaphorically. If you are exhausted after work, say 我没电了. It tells your friends you have zero social energy left.