In message , John Aldridge writes
Thanks.
It says that it will play for 15 hours, but it gives no indication as to what the battery life is if it is turned on, but not playing (e.g. standby). Something else that I didn't mention in the original post, is that this would be on 7*24, although it may not be used at all on any given day. So anything battery powered is unlikely to be suitable.
Adrian