Battery only stays charged for a few days

My battery powered doorbell has started to run out after less than a week of full charge. We’ve had some cold weather here (UK) which I know can affect the battery life, but it’s pretty mild now (over 10 degrees C at least). I’ve checked all the settings are optimised to avoid draining the battery too much and I don’t even have the sound enabled as it makes my dogs bark! Anyone had the same issue or ideas how to solve this? Thanks!