Акумулятор у павербанку.

In Ukrainian, the present-tense verb to be is often omitted.

So Акумулятор у павербанку naturally means The battery is in the power bank without needing a separate word for is.

If you want, you can sometimes add є for emphasis or clarity, but in many ordinary sentences it is simply left out.

Павербанку is in the locative case.

The preposition у here means in, and after у when you are talking about location, Ukrainian normally uses the locative.
The base form is павербанк, and the locative singular is у павербанку.

So:

• павербанк = dictionary form
• у павербанку = in the power bank

Both у and в can mean in. Very often the choice is about sound, not meaning.

Ukrainian prefers combinations that are easier to pronounce. After Акумулятор, using у sounds smoother than в.

So Акумулятор у павербанку is mainly a euphonic choice.
You may also see в in other sentences if it sounds better there.

Yes. Павербанк is a common modern loanword in Ukrainian, adapted from English power bank.

It behaves like a normal Ukrainian noun and can be declined:

• павербанк
• павербанку
• павербанком, etc.

So even though it comes from English, grammatically it is treated like a regular Ukrainian masculine noun.

Павербанк is masculine.

You can tell from both its form and the way it declines. That is why you get forms like у павербанку.

This matters when you use adjectives or past-tense verbs with it, for example:

• новий павербанк = a new power bank
• павербанк зарядився = the power bank charged up

Акумулятор usually means a rechargeable battery or accumulator.
Батарея is a broader everyday word for battery, and it can also mean other things like a radiator depending on context.

In a device like a power bank, акумулятор is more precise if you mean the internal rechargeable cell.

So this sentence uses a technically appropriate word.

It can function as a full sentence in Ukrainian.

Because present-tense is is often omitted, Акумулятор у павербанку can mean The battery is in the power bank.

Out of context, though, it can also look a bit like a short label or fragment, something like Battery in the power bank. Context usually makes it clear.

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

For example:

• Акумулятор у павербанку
• У павербанку акумулятор

Both are possible, but the emphasis changes.

The version starting with акумулятор puts the focus more on the battery.
The version starting with у павербанку puts the location first, a bit like In the power bank, there is a battery or As for the power bank, the battery is there depending on context.

Ukrainian does not have articles like English the and a.

That means акумулятор can mean:

• a battery
• the battery

and павербанку can mean:

• in a power bank
• in the power bank

The exact meaning depends on context. Ukrainian expresses definiteness through context, word order, and sometimes other words such as demonstratives.

Not always.

With у / в, the case depends on the meaning:

• location → usually locative
• motion into → usually accusative

Here it is location, so you get у павербанку = in the power bank.

Compare that with a motion idea such as put it into the power bank, where Ukrainian would use a different structure and case pattern.