اگر باتری گوشی تو تمام شد، آن را شارژ کن.

It is a Persian possessive chain:

• باتری = battery
• گوشی = phone / mobile phone
• تو = you / your (informal)

So literally it is something like:

battery of phone of you

In natural English, that becomes your phone’s battery.

Persian often builds possession this way, instead of using 's like English.

Because Persian usually uses the ezafe sound, a short linking vowel, instead of a separate word.

So the phrase is really pronounced like:

• باتریِ گوشیِ تو

That little -e / -ye link connects nouns and modifiers, but it is often not written in normal spelling.

So learners have to get used to recognizing invisible links like this.

Literally, تمام شد means became finished or ended.

In this sentence, it means the battery ran out, died, or was used up.

This is very natural Persian. تمام شدن is used for many things that get used up or come to an end, for example:

• money running out
• food finishing
• time ending
• battery dying

So for a battery, تمام شد is a normal way to say it has no charge left.

This is a very common thing in Persian.

After words like اگر and وقتی, Persian often uses the simple past for an event that is viewed as completed before the next action happens. English often uses the present in the same situation.

So:

• اگر باتری گوشی تو تمام شد
  naturally means If your phone battery runs out / when it has run out

It does not necessarily mean only a past event here. In context, it can refer to a future or general condition.

آن را means it here.

More exactly:

• آن = that / it
• را = marker of a specific direct object

So آن را شارژ کن = charge it

In formal or written Persian, آن را is perfectly normal. In everyday speech, people more often say:

• اون رو
• اونو
• or just شارژش کن = charge it

را marks a specific direct object.

In this sentence, the thing being charged is a specific thing: that / it, meaning the battery or phone.

So:

• آن را شارژ کن = charge it

Without را, the sentence would sound incomplete or unnatural here.

For learners, a good quick rule is: when the direct object is definite/specific, especially a pronoun, را is very common and often expected.

Because شارژ کردن is a compound verb.

• شارژ = charge
• کردن = to do

Together, شارژ کردن means to charge

In the imperative, کردن becomes کن, so:

• شارژ کن = charge!

Persian uses a lot of compound verbs like this, especially with loanwords and nouns.

Because Persian normally puts the verb at the end of the clause.

So:

• اگر باتری گوشی تو تمام شد
  literally follows a pattern like
  if battery phone your finished became

And:

• آن را شارژ کن
  literally feels like
  it charge do

This is normal Persian word order. English and Persian arrange sentences differently, so this is something learners need to get used to.

Yes. تو is singular and informal.

So this sentence sounds like you are talking to a friend, child, sibling, or someone you know well.

A more formal or plural version would be:

اگر باتری گوشی شما تمام شد، آن را شارژ کنید.

Changes:

• تو → شما
• کن → کنید

Yes, absolutely.

Both mean your phone:

• گوشی تو
• گوشی‌ات

The version with -ات is a very common attached possessive form. Many speakers would naturally say:

باتری گوشی‌ات

instead of

باتری گوشی تو

Both are correct. The choice is often about style, rhythm, or emphasis.

Usually, yes.

In modern everyday Persian, گوشی commonly means mobile phone / cellphone.

By itself, it can literally mean something like receiver/handset, but in normal conversation people often use it to mean phone, especially a cell phone.

So باتری گوشی naturally suggests your phone battery, not just any battery.

Yes. A very natural spoken version would be:

اگه باتری گوشی‌ت تموم شد، شارژش کن.

Common spoken changes:

• اگر → اگه
• گوشی تو → گوشی‌ت
• تمام → تموم
• آن را → ـش or اونو

So the written sentence is correct and natural, but everyday speech is often a bit shorter and less formal.

Grammatically, it refers to باتری — the battery.

So the sentence literally says:

If your phone’s battery runs out, charge it.

In real life, English speakers often say if your phone dies, but Persian here is focusing specifically on the battery. That is completely natural.