こんにちは！
携帯の電池、充電に関しては祐希さんのいうとおり die（死ぬ）という表現がよく使われます。それ以外には普通に run out of battery（充電がなくなる）とも言えます。
例：
Sorry, my phone was dead.
ごめん、携帯死んでた（充電なかった）。
Sorry I couldn't answer your call, my phone ran out of battery.
電話でれなくてごめん、充電なかったの。
My phone's out of battery.
充電がない！
ぜひ参考にしてください。
携帯電話の充電がなくなったことを想定して訳してみました。
乱暴な表現に聞こえますが、充電がなくなることをdie（死ぬ）と言います。
I couldn't contact you because my phone died.
携帯の充電がなくなったから連絡が取れなかった。
My phone is dying!
携帯の充電が無くなりそう！
携帯の充電以外でも、乾電池もThe battery died. と言うように使えます。
Sorry that I couldn't contact you because my phone was dead.
Sorry that I couldn't contact you because my phone was dead.
連絡できなくてごめん、電話の充電が切れててさ。
上記の表現で十分に伝わりますが、
「充電器を忘れてしまった」とか「充電器がなかった」という表現もできますね。
その場合は
I didn't have my charger with me.
充電器もってなくて。
I forgot to bring my charger with me.
充電器を携帯していくのを忘れてしまって。
というような表現も知ってくと便利かもしれませんね。
I was just about to contact Pete and my battery died.
I would have called but my battery went dead
You are with a friend at the airport and jhave arranged to meet Pete in the departure lounge. You know Pete is in the airport building, but where is he? You take out your phone and call Pete's number...then....your phone switches off!
"Did you speak to Pete?"
"No.I was just about to contact him and my battery died!"
あなたは空港に友人と一緒にいて、出発ラウンジでピートと会うことになっています。ピートが空港にいるのは分かっていますが、どこにいるか分かりません。携帯電話を取り出し、ピートの電話番号に電話しましたが、電話の電源が切れてしまいます。
Did you speak to Pete?
ピートと話したの？
No.I was just about to contact him and my battery died!
いいえ。連絡しようとしたんだけど、バッテリーの充電が切れちゃってね。
A) My phone died
A- i tried calling you earlier but your phone went to voicemail
B- Sorry my phone died i only got a chance to charge it now
B) My battery died
A- Can i call my mom from your phone please?
B- Sorry my battery died
I hope this helps :-)
A) My phone died
A- さっき電話をかけたんだけど、ボイスメールに繋がったよ。
B-ごめん、携帯死んでて、充電する機会がなかったの。
B) My battery died A-お母さんに電話していい？
B-ごめん、充電切れ。
お役に立てれば幸いです。
A : I was waiting for you at the bus stop. Where were you?
B : I was going to call you to say I am running later.
A : Why didn't you?
B : My phone died. I am sorry.
A : It's okay, I understand.
I was out of charge! ( I ran out of Juice!) My phone battery was flat
I wanted to call desperately..but was out of juice:-)
It is a common problem...since we all spend so much time on our phones...
Batteries do run out /go flat /lose charge/ run out of juice;-) become dead!
There is a simple solution: a separate batter booster/or recharger pack.
I keep one handy for long days when I need to be... on the phone;-)
これはよくある問題ですよね。
なぜなら私たちはとても長い時間をケータイに使っているからです。
例文
Batteries do run out /go flat /lose charge/ run out of juice ;-) /become dead!
（充電はなくなる）
単純な解決法があります。
外付けのバッテリーブースター、あるいは充電パックです。
私は長時間ケータイを使う必要があるとき、便利なこれを使います。
I'm sorry, I wasn't able to contact you because my phone's battery died while I was on the street
My phone's battery ran out when I tried to contact you today
We can say "My phone's battery died" and this is the almost the exact thing that happened. When we say "died" we don't mean that it is gone forever. Of course, it can be recharged with a phone charger once we get to a place where we can recharge it.
"My phone's battery ran out" is another way of saying this. You are basically saying that your phone's battery ran out of power and you had no way of contacting the person you wanted to contact
"My phone's battery died"（携帯の電池がなくなった）と言えます。これはすごくうまくこの状況を表していると思います。"Died" と言っていますが、これは「永遠に使えない」という意味ではありません。充電をすればまた復活します。
"My phone's battery ran out"（携帯の電池がなくなった）も同じ意味を表します。ここでは、「携帯の電池が切れて連絡するすべがなかった」と伝えています。
My phone ran out of battery thats why i couldnt contact you
When your phone runs out of battery, you can simply say my phone ran out of battery, or that it died.
If someone contacted you and you didnt reply for a while, saying sorry will let them know it wasnt your fault that you couldnt contact them and that it was out of your hands. It also comes across respectful, especially if they needed you at that particular time.
'I am so sorry I couldn't call you, my phone died.' is a perfectly respectful way of letting them know you phone died.
携帯の充電が切れたときは、シンプルに
'my phone ran out of battery'（携帯の充電が切れた）
'my phone died'（携帯の充電が切れた）
と言えます。
相手に返信するのが遅れたときは、'sorry' と言えば、そこに「致し方がない理由があった」ことが伝わります。また、特に相手が連絡を待っていたときは、これはとても丁寧な印象にもなります。
'I am so sorry I couldn't call you, my phone died.'（連絡できずごめんなさい、携帯の充電が切れてしまったんです）
は「充電が切れてしまった」のとても丁寧な言い方です。
The first two sentences more or less use the same grammatical features with the only difference being that the first sentence used the word, "dead," as an adjective, whereas , "died," is the past tense of the verb, "to die," and it functions as the main verb within the sentence.
In the last example, we are referring to the idea of, "to run out of," as a way of saying how much of something that it has. When the word, "battery," comes at the end, we can understand what exactly happened to the phone.
一つ目と二つ目の文は意味がよく似ています。唯一の違いは、一つ目の文では形容詞の "dead" を使っていて、二つ目の文では動詞 "to die" の過去形 "died" を使っていること。
三つ目の例では、「使い果たす」という意味を "to run out of" で表しています。最後の "battery"（電池）が「使い果たしたもの」です。
I couldn't get in touch because my phone ran out of battery.
My phone died so I couldn't get in contact.
My phone ran out of juice so couldn't get in touch.
I couldn't get in touch because my phone ran out of battery.
My phone died so I couldn't get in contact.
My phone ran out of juice so couldn't get in touch.
A few different sentences here, the first being more formal, or proper, and the second two more informal and perhaps colloquial. Enjoy them and use them well.
I hope it helps.
Have a great day.
Will
I couldn't get in touch because my phone ran out of battery.
My phone died so I couldn't get in contact.
My phone ran out of juice so couldn't get in touch.
（携帯の充電が切れて、連絡できませんでした）
三つ例をご紹介しましたが、一つ目はよりフォーマル、あるいは上品な言い方です。
あとの二つはカジュアルで口語的です。使い分けてみてください。
参考になれば幸いです。
良い一日を。
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