I am trying to figure out the best way to charge 20 tablets daily. I use them for a class I teach and will need to charge them every night after class. A transit case will hold 20 tablets and I would like to develop a system so I can charge them while they are stored in the case. I am trying to figure out what is the maximum number of tablets I can plug into a single wall outlet. Each tablet charger has an output of 12V/1.5A. Does anyone have any guidance. Thanks in advance for your help.