I use ameda pump as well. When I took it back to home after the first time pumping in office, I found the 乾電 doesn't work. In office, it still works. I think maybe the transportation make it out of order. So, now I can only use the plug to get electricity.
And, I use double pump to pump at the same time. As I only pump during lunch time, it is OK for me that I do not need to sterlize the pump in office.