[MattW]

Generally speaking, radios designed for crystals (Exzes plus) use 8xAA (1.5V Alkaline) batteries - i.e 12V nominal.

However, radios designed for 2.4G (Exzes X) use lower voltage - in Sanwa case, I guess they work with 6x1.5 - although as mine was supplied with a rechargable pack, it is 6x1.2. 7.2V in my case, hence it will run on 7.4V lipo.

The initial question was for Exzes X radio. Hope that clarifies it.