I’m going to be honest: when I first saw the Used Battery event in Zenless Zone Zero, I almost ignored it. That would have been a mistake. The event ran from July 5 through July 15, 2025, using server time. If you are reading this later in 2026 as a refresher or checking the mechanics in case a similar version appears again, the core loop is still worth knowing.

Before anything else, there are two requirements. You need to reach Inter-Knot Lv. 15, and you need to complete the Agent Story “Mole in the Hole (I).” Without those, you cannot even start exchanging items. I remember some players got confused because they saw the event banner but could not interact with it. More often than not, the Agent Story was still unfinished.

The daily habit is simple. After unlocking the event, just use your first Battery Charge of the day. That gives you a Used Battery. You then take that Used Battery to Sjal. She exchanges it for useful stuff like Polychromes, Boopons, and various upgrade materials. You do not need to spend a huge amount of Battery Charge in one go. The important part is doing that first daily consumption consistently.

Here is the part that can trip people up. The reward pool does not open all at once. There are seven sets of rewards in total. New sets unlock over time based on two things: your total number of login days and your current exchange progress. In practice, this means you should log in every day and also complete the previous day’s exchange. If you hold onto your Used Battery without exchanging the earlier rewards, you may block yourself from seeing the next set. The reset happens at 4:00 server time each day.

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I treated this like a short login routine. Each day, I spent a little Battery Charge to earn the Used Battery. Then I immediately exchanged it with Sjal before closing the game. That small habit saved me from scrambling later.

After you submit a total of five Used Batteries to Sjal, you can claim an additional Exclusive Reward. This is separate from the regular seven reward sets. It basically rewards consistency. Since the event lasted ten days, hitting five Used Batteries was very doable even if I missed a few days. I still aimed for daily logins because missing too many days could delay the full seven-set unlock chain.

The exchange priority depends on what your account needs. Polychromes are always valuable for pulls, so I grabbed those first when available. Boopons are great if you want more Bangboo chances. Upgrade materials helped me push some agents I had been ignoring. The nice thing is that the exchange itself uses Used Batteries, not extra premium currency. You just play, spend some Battery Charge, and turn that into progression.

A quick summary from my experience:

Step What to do
Qualify Reach Inter-Knot Lv. 15 and finish “Mole in the Hole (I)”
Daily Use your first Battery Charge of the day to get a Used Battery
Exchange Give Used Batteries to Sjal for rewards
Unlock Log in and clear previous exchanges to open new daily reward sets
Bonus Submit five total Used Batteries to claim the Exclusive Reward

One warning: pay attention to server time if you play on a region that differs from your local clock. The daily reset at 4:00 server time can arrive at an odd hour. I nearly missed one daily exchange because I assumed the reset matched my own midnight. A quick check of the server clock solved that.

Overall, the event is not hard. It rewards low-effort consistency more than heavy grinding. The key lesson I took away is simple: spend Battery Charge once a day and talk to Sjal right after. Do that, and the Polychromes, Boopons, and upgrade materials will pile up without much stress. If another Used Battery-style event shows up in 2026, I’ll be following the same routine.