Raspberry Pi 5 official RTC Battery

Every Raspberry Pi 5 contains a built‑in RTC (Real‑Time Clock), which can keep time when the Pi is powered off – but only if you connect an official Raspberry Pi 5 battery to the connector on the board.

We will be using Panasonic ML-2020 Lithium Manganese Dioxide battery. This battery comes with adhesive tape so you can even tape it inside the Raspberry Pi case:

Specs

Nominal Voltage 3 V
Continuous Standard Drain 0.12 mA
Nominal Capacity 45 mAh
Weight  2.2g