wǒ de shǒujī kuài méidiàn le, wǒ děi xiān gěi ěrjī chōngdiàn.

的 links a possessor to a noun.

• 我 = I / me
• 我的手机 = my phone

So the pattern is:

possessor + 的 + noun

This is one of the most basic and common uses of 的. In some close relationships, Chinese can sometimes omit 的 (for example 我妈 for my mom), but with something like my phone, 我的手机 is the normal form.

Not here. In this sentence, 快 does not mean fast. It means almost or about to.

So:

• 快没电了 = is almost out of battery
• not is fast out of battery

This is a very common pattern:

快 + verb/adjective phrase + 了

It means something is going to happen soon.

Examples:

• 天快黑了 = It’s getting dark soon / It’ll be dark soon.
• 我快迟到了 = I’m about to be late.

没电 literally looks like no electricity, but in everyday Chinese it means out of battery, dead, or has no charge.

It is used for devices such as:

• 手机没电了 = The phone is out of battery.
• 耳机没电了 = The headphones are out of battery.
• 遥控器没电了 = The remote is out of battery.

This is a fixed, very natural expression. English speakers should learn 没电 as a chunk.

Chinese normally uses 没 for not have / there isn’t / lacking. So 没电 means doesn’t have power/charge.

• 没电 = common everyday way to say out of battery
• 没有电 = also possible, but a little fuller and less conversational
• 不电 = not correct here

So for devices, 没电 is the expression you will hear most often.

This 了 is not a past-tense marker. It is a sentence particle showing a new situation, change of state, or current relevance.

In 快没电了, it helps give the sense that the phone is reaching a new state: it is about to be dead.

Compare:

• 手机快没电 = understandable, but less natural
• 手机快没电了 = natural, immediate, current situation

So here 了 adds the feeling of this is happening now / this is becoming the case.

Yes. 快没电了 and 快要没电了 are both natural.

• 快没电了 = almost out of battery
• 快要没电了 = almost about to run out of battery

快要 sounds a little fuller, but in everyday speech, 快没电了 is very common and natural.

Here 得 is pronounced děi, and it means must, have to, or need to.

So:

• 我得先给耳机充电 = I need to charge the headphones first

This is important because 得 can have different pronunciations and functions in Chinese:

• de in 我的 → structural particle
• dé in 做得好 → used in complements
• děi in 我得走了 → must / have to

So in this sentence, it is the děi form.

先 means first, and it usually goes before the verb phrase it modifies.

So:

• 我得先给耳机充电 = I need to first charge the headphones

This is normal Chinese word order. Adverbs like 先, 都, 也, 就, 还 often come before the main action.

A useful pattern is:

先 ... 再 ...

Examples:

• 我先吃饭，再工作。 = I’ll eat first, then work.
• 先给耳机充电，再给手机充电。 = First charge the headphones, then charge the phone.

Here 给 works like a preposition, roughly meaning for or to. It introduces the thing receiving the action.

So:

• 给耳机充电 = charge the headphones / charge power for the headphones

The structure is:

给 + thing + verb

In this sentence:

• 给耳机充电 = charge the headphones
• literally, something like provide charging to the headphones

This is the natural Chinese pattern. English speakers often want to map it word-for-word, but it is better to learn 给 + object + 充电 as a standard structure.

充电 is best learned as a fixed verb meaning to charge / recharge.

Even though it literally looks like fill + electricity, in real usage it behaves like a standard action word:

• 给手机充电 = charge the phone
• 给耳机充电 = charge the headphones
• 我在充电 = I’m charging it

You will also hear forms like:

• 充一下电 = charge it a bit / give it a quick charge
• 充了电 = charged it / has been charged

So yes, it has internal structure, but for learners, treating 充电 as one common verb is the most helpful approach.

Yes. Since the subject is the same in both clauses, Chinese often omits it if the meaning is clear.

So all of these are natural:

• 我的手机快没电了，我得先给耳机充电。
• 我的手机快没电了，得先给耳机充电。

Keeping the second 我 can make the sentence a little clearer or slightly more emphatic, but omitting it is very common in natural speech.

No. Chinese often puts related clauses next to each other without an explicit connector, especially in casual speech.

So this is perfectly natural:

• 我的手机快没电了，我得先给耳机充电。

If you want to make the logic more explicit, you could say:

• 因为我的手机快没电了，所以我得先给耳机充电。

But in everyday Mandarin, leaving out 因为 and 所以 is very common when the relationship is obvious from context.

The difference is whether the phone is almost dead or already dead.

• 手机快没电了 = The phone is almost out of battery.
• 手机没电了 = The phone is already out of battery.

So 快 changes the meaning a lot. It tells you the problem has not fully happened yet, but it is about to.