I would suggest getting a "Power Conditioner". Google for it and you will find information about them. Often times they are sold in music and TV/Multi-media places.
But having your home electric supply checked out would be a good idea as well.
Our home has tons of iPod, iPad, iPhone charges and we've only lost 1 in the last 4 or 5 years. So if you are loosing 4 or 5 in just a few months, you have power issues. Or you Cat/Dog/Hampster is doing something to them when you are not looking