None that I know about officially. Unlike the older generation of batteries that had a memory, the ones used in the Sony Reader should not have a memory.
Some time ago I thought that I was having a problem with the battery not keeping a charge as long as it did when it was new. I remembered that when I first had the unit I would always use the AC charger and later I would just recharge on the USB connection. I recharged on the AC unit a few times and the problem seemed to vanish. Either it cured itself or I started to kid myself. Either way, I will now use the AC charger every so often and fill in with the USB charging when I load and unload books.
There is a certain amount of battery drain when you use a Memory Stick (in theory less drain than an SD card) but not so much as your unit seems to be experiencing.
If you are not already using the AC charger for the unit, try it, it just might work.
Good luck and welcome to MobileRead.
