The battery life in used hybrid vehicles is much less of a potential problem than it is for pure electric vehicles, as hybrids use their batteries less of the time, and even as the battery health declines with age it does not prevent the car from driving correctly - it just means a slight reduction in efficiency compared to when the car was new. Even so, buying the youngest car with the lowest mileage that you can afford will maximise the battery life. While cold weather does reduce battery performance, again this is much less of an issue with hybrid vehicles so there is no need for concern.