Stop buying expensive or even the cheap brand batteries that will last one month! With this system you only need to modify and old dead battery and it will work with the same with this modified 'battery' that will be plugged for a continue operation and with the old conventional batteries.
Step 1: Step 1: You Need a Power Supply
This is the heart, I bought this online for $17 and this will be the most expensive part.
I am using a 19V and 19Amps power supply to convert from 110V AC to 18-19V DC.
Step 2: Step 2: Adapt Your Batteries and Connect the System
As shown in the video I am using these DC adapters that cost about $2 all 10.