The battery box is the starting point of any LEGO Power Functions (LPF) construction, which delivers power to drive the functions. The battery box has the LPF female plug, which contains the 4 connections of the LPF system: 2 for power supply and 2 for control.
The power supply of the LPF system runs unbroken throughout your entire construction, where the female plugs are the feeding plugs. This means that from any female plug you have direct connection to the power. So it works similar to the power supply of an extension cord in your house.
This battery box holds 6 AA batteries. To get the best result you should use alkaline or rechargeable batteries. When you change batteries remember to replace all 6 with new fresh ones.
To change batteries, take off one lid on each side and insert 3 AA batteries in each side.
Battery lifetime will depend heavily on the way it is used and on the quality of the batteries. This battery box delivers up to 800mA. You can drive 2 XL Motors or 4 Medium motors together. If you exceed the maximum current, the overload protection will kick in.
You should then disconnect everything from the box and turn it off for a while before turning the power back on again.
You can connect any combination of LPF elements to the plug and then you use the Control switch to operate the function. In the middle position power is OFF. By pushing the switch in either direction you turn power ON and control the function in either direction. When power is ON, the green indicator LED will light up.
This battery box has LEGO TECHNIC building interface and the size is 4 x 11 x 7 modules.