Canon Speedlite 600EX-RT Setup page 22

12-Set to 1.
Flash Recycle.
If you never intend to use an external battery
or power source with your
flash units then go with the
default setting.
If you use and external
battery then set it to 1.
You will be separately distributing
the power of recharging.
The each and every shot will be assigned to the
external battery.