How does a phone store date and time even when the battery is removed? I have seen android phones which do not ask users to set the date and time even if I remove battery and reinsert and start the phone. If I have a SIM card inside it, I understand it fetches date and time from the network provider. But what if I do not have SIM and there is no Wi-Fi connected?
“There is in fact a second battery in every phone.” (Cf. answers 15., 19. and 48. of this discussion.)