I drove out to give him a jumpstart because his battery was dead.

我把车开出来帮他做借电启动，因为他的电池没电了。

《柯林斯英汉双解大词典》

My phone battery is almost dead now.

我的手机电池快没电了。

youdao

After all, none of the functions work once the phone's battery is dead.

毕竟，一旦手机电池没电了，那些功能将全部丧失。

youdao

She went on to say that she used them often, but mostly when her cell phone battery was dead.

CNN: Pay phones: The search for an endangered species

"Attempts have been made to ring the mobile but we believe that the battery is dead or the credits have run out, " said a police spokesperson.

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But, police say, there was no activity on Kopetsky's cell phone after she walked out of school, indicating that the battery went dead or was removed from the phone.

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