I always used my Madela Mini-Electric on mains power........twice a day for 6 months each baby, plus my GF used it between Olivia and Charlie, no probs at all, and it is still going strong..........I never used it on battery, I used to plug in whilst I sat on teh couch and watch TV with my boobs hanging free........NIOCE!
Classy Lucy! But sooooo true! I have giant - shall I say bazookas (lol) and I used to have them hanging out on the pump 3 hourly for 7 weeks! I even took it to the shops with me when I was out for the day!

I lovvveeeedddd my Medela Mini Electric Pump. It was the best $130 I spent with either child! I bought this one initially because it is the pump that is recommended by the ABA.