Learn Hardcore Croatian: Uvijek nosim punjač sa sobom, jer baterija brzo padne kad gledam serije. - I always carry a charger with me, because the battery drops quickly when I watch series.

Before the verb (most common, as in the example):
- Uvijek nosim punjač sa sobom.
After the verb (also possible, slightly different rhythm/emphasis):
- Nosim uvijek punjač sa sobom.
Sometimes between the verb and the object (more marked emphasis):
- Nosim punjač uvijek sa sobom.

All are grammatically correct; the first (as in your sentence) is the most neutral and natural.

Why is the verb nosim used here, and what form is it?

Nosim is the 1st person singular, present tense of the verb nositi (to carry, to wear).

Infinitive: nositi = to carry / to wear
1st person singular present: nosim = I carry / I wear

In this sentence, it expresses a habitual action:

Uvijek nosim punjač sa sobom = I always carry a charger with me (as a general habit, not just right now).

Other forms (for comparison):

ja nosim – I carry
ti nosiš – you carry (singular)
on/ona/ono nosi – he/she/it carries
mi nosimo – we carry
vi nosite – you carry (plural/formal)
oni/one/ona nose – they carry

Why is it punjač and not some changed form like punjača? Which case is it?

Punjač means charger.
In this sentence, punjač is the direct object of nosim, so it is in the accusative case.

For inanimate masculine nouns like punjač, the accusative singular has the same form as the nominative singular:

Nominative (who/what?): punjač – a charger
Accusative (whom/what?): (nosim) punjač – (I carry) a charger

So:

Nosim punjač. = I carry a charger.
The word punjač looks exactly the same in nominative and accusative.

Why do we say sa sobom? What does sa mean here, and why not just sobom?

Sa sobom literally means with myself / with me (referring back to the subject I).

s / sa = with (preposition)
sobom = the instrumental form of the reflexive pronoun (roughly “oneself”), used when the subject and the object are the same person.

You cannot say just sobom here; you need the preposition:

✅ sa sobom – with me (myself), with you (yourself), etc.
❌ sobom alone – ungrammatical in this context

You could also say:

Uvijek nosim punjač sa sobom.
Uvijek nosim punjač sa sobom u torbi. – I always carry a charger with me in my bag.

What is the difference between sa sobom and sa mnom?

Both are translated as with me, but they are used slightly differently:

sa mnom – literally with me (instrumental of ja = I)
- Focuses more on you and me as separate people:
  - Ponijela je knjigu sa mnom. – She brought the book with me.
sa sobom – literally with oneself, reflexive
- Refers back to the subject of the sentence, whatever person that is:
  - Uvijek nosim punjač sa sobom. – I always carry a charger with me (my own charger, that I keep on me).
  - Uvijek nosi punjač sa sobom. – He/she always carries a charger with him/her.

In your sentence, sa sobom is natural because the charger belongs to and is carried by the same person who is the subject (I).

What does jer mean, and why is there a comma before it?

Jer means because.

Uvijek nosim punjač sa sobom, jer baterija brzo padne kad gledam serije.
= I always carry a charger with me, because the battery runs out quickly when I watch series.

In Croatian, a comma is normally used before conjunctions like jer when they introduce a subordinate clause (a “because” clause, “when” clause, etc.).

So:

... , jer baterija brzo padne ... – comma before jer is standard.

What does baterija brzo padne literally mean, and why use padne and not pada?

Literally:

baterija = the battery
brzo = quickly
padne = (it) falls / drops (perfective)

So baterija brzo padne literally is the battery quickly falls, but idiomatically it means the battery goes down quickly / dies quickly / runs out quickly.

About padne vs pada:

padati (imperf.) – pada (present) = to be falling, an ongoing process
- Baterija brzo pada. – The battery is (in the process of) dropping quickly.
pasti (perf.) – padne (present form with future-like or repeated meaning) = to fall (completely)
- Baterija brzo padne. – The battery (typically) ends up empty quickly; it goes from OK to low/dead fast.

In this context, padne suggests that the battery ends up low/empty very fast whenever you watch series, as a repeated pattern. It sounds very natural and colloquial.

Where is “my” in baterija? Why isn’t it moja baterija?

Croatian has no articles (a / the) and often omits possessive pronouns (moj, tvoj, njegov, njezin...) when the owner is obvious from context.

Here, it is clear we mean my phone’s battery / my battery, so just baterija is enough:

... jer baterija brzo padne ...
= because the battery runs out quickly (understood: my phone’s battery).

You could say:

... jer mi baterija brzo padne ... – because my battery quickly dies.
But the simple baterija is perfectly normal and natural.

What does kad mean here, and how is it different from kada?

Kad means when.

kad gledam serije = when I watch series.

Kad and kada:

kada is the full form, a bit more formal or careful.
kad is the shortened, very common spoken form.

In most everyday situations, they are interchangeable:

kad gledam serije
kada gledam serije

Both mean the same; your sentence uses the common short form kad.

Why is gledam in the present tense, even though this describes a general habit?

In Croatian, the present tense is used for:

current actions (I am watching)
regular/habitual actions (I watch)
and also for general truths or whenever/when-type clauses.

So:

kad gledam serije = when(ever) I watch series / when I’m watching series.

The context tells us it is about a repeated situation (every time you watch series, the battery dies quickly). You don’t need a special tense; the present covers this habitual meaning.

Why is it serije and not serija?

Serija (singular) = series / show
Serije (plural) = series (multiple)

In kad gledam serije, serije is accusative plural of serija:

Nominative plural: serije – series
Accusative plural: serije – (I watch) series

You say serije because:

you usually watch more than one episode or show, and
Croatian often uses the plural where English also tends to say series (which looks singular in form but can be plural in meaning).

So:

Volim gledati serije. – I like watching series / TV shows.

Can the word order of the whole sentence change? For example, can jer-clause come first?

Yes, Croatian word order is fairly flexible. You can move clauses for emphasis or style:

Original:

Uvijek nosim punjač sa sobom, jer baterija brzo padne kad gledam serije.

Possible alternative:

Jer baterija brzo padne kad gledam serije, uvijek nosim punjač sa sobom.

Both mean the same. The second one slightly emphasizes the reason first.

Within each clause, you also have some flexibility, for example:

Uvijek punjač nosim sa sobom. (stronger stress on charger)
Uvijek sa sobom nosim punjač. (slight emphasis on with me)

All these are grammatically correct, but the original sentence is the most neutral and natural.