Sanwa Exzes battery question

[colin76]

Hi all, I have a Sanwa Exzes transmitter, I am happy with it apart from one thing. The voltage cut off protection is automatically set at 11v, when I charge my pack (9.6v pack), even stopping it at around 10.7v, when I put it in the transmitter that annoying alarm buzzes "over voltage", so it's out with the pack and discharge it, try it back, then usually repeat the process a couple of times until the transmitter works. I felt a 7.2v pack would drain too quickly. Another option is a 7.2v lipo, any one else had these issues?