Rechargeable batteries can be used, and rechargeable batteries have the same voltage as Nanfu batteries.
Millet smart lock can use Nanfu battery, because the voltage of Nanfu battery is 1.5V, millet smart lock. You can use dry batteries, but the millet smart lock can not use rechargeable batteries, because the rechargeable battery voltage is relatively low, which will affect the normal use of millet applications, so I think the millet smart lock can use two pairs of batteries.
We don't need to, because we're using 220 volts AC