Honestly, a rechargable low discharge battery is your best bet. The other option would be to get a GG battery pack and have it rebuilt with better/newer cells.
Originally Posted by StarMist
A spine card is the hymen of a new game assuring its first owner that he is truly her one and only, and of a used game assuring its new owner that whilst she has been played with in the past that play has never been too careless or thorough.