I've been poking around all day and am good and flumuxed... 
I have an RN4075, which I understand is like the 901... I think I read that you could use KR808 batteries on the 4075, but I'm not sure... I'm just trying to find a battery that will last a little longer than 3-4 hours without investing in a whole new setup or getting into complicated mods... good prophets has this:
Joye 510 PCC - Personal Charging Case - Limited Quantities!
out of stock, but kind of what I was thinking...
Any advice would be greatly appreciated!

I have an RN4075, which I understand is like the 901... I think I read that you could use KR808 batteries on the 4075, but I'm not sure... I'm just trying to find a battery that will last a little longer than 3-4 hours without investing in a whole new setup or getting into complicated mods... good prophets has this:
Joye 510 PCC - Personal Charging Case - Limited Quantities!
out of stock, but kind of what I was thinking...
Any advice would be greatly appreciated!