hyudaepon baeteoriga da chasseoyo.

A natural breakdown is:

• 휴대폰 = cellphone / mobile phone
• 배터리 = battery
• -가 = subject particle
• 다 = all, completely, fully
• 찼어요 = became full / filled up

So the sentence literally feels like:

As for the cellphone battery, it became completely full.

That is why the natural English meaning is The phone battery is fully charged or My phone battery is fully charged.

-가 marks 배터리 as the subject of the sentence.

The thing that has reached a full state is the battery, so Korean marks 배터리 with -가:

• 배터리가 다 찼어요 = The battery is completely full

Even though 휴대폰 comes before it, 휴대폰 is just describing what kind of battery it is: phone battery.

So the structure is basically:

• 휴대폰 배터리 = phone battery
• 휴대폰 배터리가 = the phone battery + subject marker

Here, 다 means completely, entirely, or all the way.

It adds the idea that the battery is not just somewhat charged, but fully charged.

Compare:

• 배터리가 찼어요 = The battery filled up / got full
• 배터리가 다 찼어요 = The battery got completely full / is fully charged

So 다 is what gives the sentence the sense of fully.

Yes — and that is exactly why it is used here.

The verb 차다 means to fill up or to become full. For batteries, Korean often talks about them as becoming full, not just as being charged.

So:

• 배터리가 차다 = the battery fills up
• 배터리가 다 찼어요 = the battery filled up completely

In English, we usually say The battery is charged or The battery is fully charged, but Korean often expresses this with the idea of becoming full.

This is a very natural Korean way to say it.

Yes, 찼어요 is the past form of 차다.

• dictionary form: 차다
• past polite form: 찼어요

Literally, it means became full or filled up.

But in English, when something has already become full and is now in that state, we often translate it as:

• The battery is fully charged
• The battery has fully charged

So even though the Korean form is past, the natural English translation may sound present because it describes a current result.

Yes, absolutely.

• 휴대폰 배터리가 다 찼어요 = The phone battery is full / fully charged
• 휴대폰 배터리가 충전됐어요 = The phone battery got charged / has been charged

The difference is mostly in nuance:

• 다 찼어요 focuses on the battery reaching a full state.
• 충전됐어요 focuses on the action/result of charging.

If you specifically want to say fully charged, 다 찼어요 is very natural.

In Korean, nouns often directly modify other nouns without 의, especially in everyday speech.

So:

• 휴대폰 배터리 = phone battery
• 휴대폰의 배터리 = the battery of the phone

Both are grammatically possible, but 휴대폰 배터리 sounds more natural and more common in ordinary conversation.

This is similar to how English prefers phone battery over the battery of the phone in many situations.

It can mean any of those depending on context, but most often in real conversation it means something like:

• the phone battery
• my phone battery

Korean often leaves out possessives like my when they are obvious from context.

So if you are talking about your own phone, 휴대폰 배터리가 다 찼어요 will naturally be understood as:

My phone battery is fully charged.

찼어요 is pronounced roughly like 차써요.

That happens because when ㅆ is followed by 어, the sound is resyllabified in speech.

So:

• spelling: 찼어요
• pronunciation: 차써요

A rough English approximation would be cha-sseo-yo, though Korean pronunciation is more precise than English spelling can show.

Yes, 찼어요 is the standard polite style.

Here are some levels:

• 배터리가 다 찼어 = casual
• 배터리가 다 찼어요 = polite
• 배터리가 다 찼습니다 = formal

So if you are speaking to a friend, 찼어 is fine.
If you are speaking politely in most everyday situations, 찼어요 is the safest choice.

Yes. Because 차다 means to become full, it is used with many things.

For example:

• 물이 다 찼어요 = The water filled up completely.
• 잔이 찼어요 = The glass is full.
• 배가 찼어요 = I’m full. / My stomach is full.

For a battery, Korean extends the same full idea:

• 배터리가 다 찼어요 = The battery is full / fully charged

So this sentence is part of a broader Korean pattern, not a one-off expression.