Replacement Battery for Futaba 8FG super?

[wanna_be_pilot]

Hi guys,

can anyone suggest to me the Lipo rating for a transmitter battery that i can use for my 8FG super?
The stock battery has a 7.2v 1700mah rating. It fully charges up to 8.5V( same as 2s Lipo?)
Is it advisable to do so? and what rating of battery? Even better, where can i get one?
any help would be deeply appreciated.

Problem Faced...

I just recently bought my Futaba Transmitter and realized after a few flying sessions that my transmitter bbattery is not able to hold the voltage. It drops really fast. Lets say i leave the house with 8.4V, by the time i reach the field, it would be 8.0V. and while i am flying, it would drop even further. Quite dangerous when you are flying.

[randomtask]

I just use 2s batteries. No need high c rating.