hyudaeponeul chungjeonharyeodaga jamdeureosseoyo.

It means something like while intending to charge it / just as I was about to charge it / I was going to charge it, but...

The key nuance is:

• the speaker had the intention to do 충전하다 (to charge)
• but that action was interrupted or did not get completed as planned
• something else happened instead

So in this sentence, 휴대폰을 충전하려다가 잠들었어요 means the speaker was about to charge their phone, but then fell asleep instead.

It comes from:

• 충전하다 = to charge
• verb stem: 충전하-
• -(으)려다가 = was going to do X, but then...

So:

• 충전하- + 려다가 → 충전하려다가

This grammar attaches directly to the verb stem.

Basic pattern:

• vowel or ㄹ ending stem → -려다가
• other consonant ending stem → -으려다가

Examples:

• 가다 → 가려다가 = was going to go, but...
• 먹다 → 먹으려다가 = was going to eat, but...

-(으)려다가 usually shows:

1. an intention or attempt
2. a change of course, interruption, or unexpected result

So it often has the feeling of:

• I was going to do X, but...
• I started to do X, but then...
• I almost did X, but instead Y happened

In this sentence, the speaker did not simply mention two past events. They are showing that charging the phone was the plan, but falling asleep prevented it.

Usually, yes.

Because -(으)려다가 strongly suggests that the intended action was interrupted, the natural interpretation is:

• the speaker meant to charge the phone
• but fell asleep before doing it, or before finishing it

So most listeners would assume the phone probably did not get charged.

That said, context always matters. In some situations, a person might have plugged it in and then fallen asleep, but without extra context, the default reading is that the charging plan was not carried out successfully.

Because 휴대폰 is the direct object of 충전하다.

• 휴대폰 = cell phone
• -을 / -를 = object particle
• 충전하다 = to charge

So 휴대폰을 충전하다 means to charge the phone.

Since 휴대폰 ends in a consonant, it takes -을:

• 휴대폰 + 을 → 휴대폰을

If the noun ended in a vowel, you would use -를 instead.

Because 잠들다 and 자다 are not exactly the same.

• 자다 = to sleep
• 잠들다 = to fall asleep

In this sentence, 잠들었어요 is better because the important point is the moment the speaker unintentionally drifted off before charging the phone.

Compare:

• 잠들었어요 = I fell asleep
• 잤어요 = I slept

잠들었어요 highlights the accidental transition into sleep, which fits the meaning of I was going to charge my phone, but then I fell asleep much more naturally.

Korean often omits the subject when it is clear from context.

So even though English usually needs I, he, she, etc., Korean often leaves it out if the listener can easily understand who is being talked about.

In this sentence, the most natural implied subject is I:

• (저는) 휴대폰을 충전하려다가 잠들었어요.
• I was going to charge my phone, but I fell asleep.

Adding the subject is possible, but often unnecessary in everyday Korean.

They are very similar, and both can be translated naturally as I was going to charge it, but I fell asleep.

But the nuance is slightly different:

• 충전하려다가 잠들었어요

  • more directly connects the intention to the unexpected result
  • often feels a bit more immediate: I was just about to charge it, but then...

• 충전하려고 했는데 잠들었어요

  • emphasizes the plan or intention a bit more explicitly
  • can feel slightly more explanatory: I had intended to charge it, but I fell asleep

So -(으)려다가 often sounds a little more like the action was right on the verge of happening when something interrupted it.

잠들었어요 is in the standard polite style.

Breakdown:

• 잠들- = verb stem
• -었- = past tense
• -어요 = polite ending

So the full sentence is polite and appropriate for everyday conversation.

It is less formal than:

• 잠들었습니다

and more polite than:

• 잠들었어

So 휴대폰을 충전하려다가 잠들었어요 is a very normal, natural sentence for speaking politely in daily life.

It can be translated either way, depending on context.

• 휴대폰 literally refers to a mobile phone / cell phone
• in natural English, people often just say phone

So this sentence could be translated as:

• I was going to charge my cell phone, but I fell asleep.
• I was going to charge my phone, but I fell asleep.

Both are fine. In most everyday English, phone sounds more natural unless you specifically want to contrast it with a landline.