If you want to convert an appliance that runs on electricity to run on battery power, the easiest way to do it is to plug in an AC adapter. If your appliance can’t be plugged into an adapter, you can hard-wire a rectifier directly to that appliance. A rectifier converts AC current to DC current so you can run your appliance in areas where there is no electricity.take “Dell Inspiron 1501 AC Adapter” for example:

Dell Inspiron 1501 AC Adapter 65W 19.5V 3.34A(http://www.udtek.com/dell-inspiron-1501-ac-adapter-65w-195v-334a-p-3090.html)

Description:
Input: AC100-240V (worldwide use)
Output: DC19.5V 3.34A
Power: 65W
Connecter size:
Internal Diameter: 5.0mm
External Diameter: 7.4mm
With central pin inside
Item Includes: AC Adapter and Power Cord.

1.Open the appliance and expose the electrical wires. The four wires in your appliance will connect to corresponding wires on the rectifier.

2.Connect the output wires. These wires are usually yellow or labeled with the tilde (~). Twist the exposed ends of the wires together and secure with an end cap. There will be two sets of these wires; connect either one in the appliance to either one in the rectifier.

3.Connect the power wires. These wires are usually red and labeled with the plus sign (+). Twist the exposed ends of the wires together and secure with an end cap.

4.Connect the ground wires. These wires are usually black or green and labeled with the negative sign (-). Twist the exposed ends of the wires together and secure with an end cap.

5.Once you’ve connected the power wires, replace the protective cover on the appliance and turn it on.