Я всегда кладу зарядку в карман рюкзака перед поездкой.

Yes, зарядка can mean two different things:

• morning exercise / warm-up
• charger or charging cable/device in everyday speech

In this sentence, зарядка clearly means charger, because you put it in a backpack pocket before a trip. The context makes the meaning clear.

Because зарядку is the accusative case, which is used here for the direct object of the verb кладу (I put).

The dictionary form is зарядка.
In the accusative singular, it becomes зарядку.

So:

• зарядка = nominative
• зарядку = accusative

In this sentence, the speaker is putting the charger, so Russian uses the accusative.

Кладу is the 1st person singular form of класть, meaning to put / to place.

So:

• я кладу = I put / I am putting

It is used here because the sentence describes a habitual, repeated action:
I always put the charger in the backpack pocket before a trip.

Because кладу and положу express different aspects.

• кладу comes from класть = imperfective
• положу comes from положить = perfective

Here the sentence talks about something the speaker does regularly / habitually: always before a trip. For repeated habits, Russian normally uses the imperfective, so кладу is the natural choice.

Compare:

• Я всегда кладу зарядку... = I always put the charger...
• Я положу зарядку... = I will put the charger... / I’ll place it...
  This sounds like one future action, not a habit.

In standard Russian, ложу is generally considered nonstandard in this meaning.

The normal standard verb pair is:

• класть → кладу
• положить → положу

So a learner should use:

• Я кладу
• Я положу

not Я ложу.

Because Russian distinguishes between:

• motion into a place → в + accusative
• location in a place → в + prepositional

Here the charger is being moved into the pocket, so Russian uses:

• в карман = into the pocket

Compare:

• Я кладу зарядку в карман. = I put the charger into the pocket.
• Зарядка в кармане. = The charger is in the pocket.

So:

• в карман = direction / destination
• в кармане = location

Because карман рюкзака means the backpack’s pocket or the pocket of the backpack.

Russian often shows this of relationship by putting the second noun in the genitive case.

So:

• карман = pocket
• рюкзак = backpack
• карман рюкзака = backpack pocket / pocket of the backpack

The form рюкзака is the genitive singular of рюкзак.

Because the preposition перед takes the instrumental case when it means before in time or in front of in space.

The noun is:

• поездка = trip

In the instrumental singular, it becomes:

• поездкой

So:

• перед поездкой = before the trip

This is a very common pattern:

• перед уроком = before the lesson
• перед встречей = before the meeting
• перед поездкой = before the trip

Yes. Russian word order is more flexible than English word order.

The sentence Я всегда кладу зарядку в карман рюкзака перед поездкой is neutral and natural, but other orders are also possible, depending on emphasis.

For example:

• Перед поездкой я всегда кладу зарядку в карман рюкзака.
  This emphasizes before the trip.

• Зарядку я всегда кладу в карман рюкзака перед поездкой.
  This emphasizes the charger.

The original version is a good neutral word order for learners.

Not always. Russian often drops subject pronouns when the verb already makes the subject clear.

Since кладу already means I put, the sentence could be:

• Всегда кладу зарядку в карман рюкзака перед поездкой.

That still means I always put the charger in the backpack pocket before a trip.

However, Я is perfectly natural too. It may be included for clarity, contrast, or emphasis.

Поездка usually means a trip, especially a specific journey or outing.

It is often more concrete than English travel.

So here:

• перед поездкой = before a trip

If you said перед путешествием, that would sound more like before a journey/travel adventure, often something longer or more significant.

So поездка is a very natural choice for an ordinary trip.

It is one very natural way, yes.

карман рюкзака literally means pocket of the backpack, and Russian often uses this structure where English uses a noun-noun combination.

English:

• backpack pocket

Russian:

• карман рюкзака

You may also hear phrases like в кармане рюкзака in other contexts, when the meaning is in the pocket of the backpack and the grammar requires a different case. But in this sentence, because of motion into the pocket, в карман рюкзака is correct.