This is the most common setup we use in all of our base builds. One setup is sufficient on vanilla, but recommend atleast 2-3 on modded servers. (We use 3 on 2x modded due to all turrets connected)
We use this mostly for turrets and can run 9 of them when power is out. You can use it however you like and can continue the power by connecting more Electrical Branches from the power out from last branch.
Beware! The branch out on first Electrical Branch is set at 5 and that will charge the battery while rest of the power goes to circuit. You may want to increase to a higher number to charge battery faster.
The backup will only give a maximum of 100 power to circuit when power is out, so keep that in mind when connecting more turrets on the circuit.