Depends on the condition of the battery (cell imbalance etc), and local OAT. You will probably find that they have had problems on that particular operation with battery maintenance, leading them to err on the side of caution.
My experience is that most pilots treat the aircraft battery like they would a cars battery, a neverending supply of lights and GPS power to read papers by. Only some of them realise that it might only last for less than half an hour, and that is on a good day (no matter what the legislation says).
Hence the reason for the smiling Avionic engineer changing the battery for you.