I am running an upgraded nimh pack in mine. I have replaced (3) so far. I have had good luck with the High Energy from Hobby People. I picked this up on sale for $20.00
http://www.hobbypeople.net/gallery/233832.asp
I just did a slow charge discharge cycle on them and they work pretty well.
In the RDS8000 thread, they list the lipo battery. I did not search there.
Dru.