The battery provided with the Yaesu VX-7R is the FNB-80LI, which is 7.4 volts and rated at 1400mAH. The life expectancy during heavy transmit duty cycle is less than 45 minutes. During extended deployments a second and even a third battery is required. Optionally, and if a generator is available or other 120 volt AC source, you may bring a charger with you.

Another option is to bring along one or more clam shell battery holders. The FNB-23 is available for the VX-7R, but in my opinion, it is a poor choice during any deployment. The FNB-23 only holds 2 AA batteries that deliver 3.0 volts instead of the 7.4 volts provided by the standard lithium-ion FNB-80LI. Your transmit power output will be 1 watt or less and battery life will be poor. The only upside to the clam shell is that if you are working a large disaster where a supply system is in place, AA batteries are readily available.