furui denchi o atarashii denchi ni kaemasu.

I replace the old battery with a new one.

Breakdown of furui denchi o atarashii denchi ni kaemasu.

• に: destination particle
• を: direct object particle
• 新あたらしい: new
• 古ふるい: old

Questions & Answers about furui denchi o atarashii denchi ni kaemasu.

Why is there no subject in this sentence?

In Japanese, the subject (like I or you) is often omitted when it’s clear from context. Here, since we understand who’s doing the replacing, the sentence simply starts with 古い電池を新しい電池に替えます without stating a subject.

Why are 古い電池 and 新しい電池 marked by を and に, respectively?

The particle を marks 古い電池 as the direct object (the thing being replaced). The particle に marks 新しい電池 as the target or result of the action—i.e. what the old battery becomes after replacement.

What’s the role of に here and can I use と instead?

に indicates the new state or target in A を B に 替える. If you use と (as in 古い電池を新しい電池と替える), it would mean “replace together with,” which doesn’t convey “into.” To express “replace A with B,” always use A を B に 替える.

What does the verb 替えます mean here, and why is this kanji used?

替えます is the polite form of 替える (かえる), meaning “to replace” or “swap out.” The kanji 替 highlights substitution. In casual speech you’d say 電池を替える, while 替えます is the polite version you might use with customers or in formal situations.