my way was to glue original battery to the backcover so when cover is removed the battery comes out too. the i did a little hole in the back cover and put some wires trough it and then connect the wires to the "inside battery" and glued another battery to the outside of back cover and then connected the wires to it. did not need to order mugen cover and to original lens cover is there too works fine but charging time is double the time that it would be with just one orig. battery. i was expecting this though