I'm attempting to build a compact way to charge six laptops (of the same model) so that I may avoid using six individual power cables. I'm trying to make it cost-effective yet safe.
My initial design was to take a simple 24V 15A DC power supply off Amazon and branch the output connection to six individual boards that each drop the voltage to a specific value using an LM317T. However, all parts including an enclosure came out to be about $45. I need 5 of these power hubs. Additionally, the charger for this brand of laptop is rated at 19.5V 3A. Wouldn't that mean that all six laptops draw a combined load of 18A, or does the manufacturer design the charger with some sort of leeway?
I am unable to find any DC power supplies that exceed 15A and are under $30. How hard would it be to build something that is capable of providing, let's say, 20A? Could I take a circuit designed for 5A and substitute parts that are rated for higher amperages?
Below, I've provided an image that illustrates the device I'd like to build:
Best Answer
This is unlikely to work. Most laptops nowadays have more than just power and ground going between them and the charger. There is often a communication channel too. The laptop and the charger communicate over some proprietary protocol so that the laptop can scale back and not give you full charging features if you try to use something other than the manufacturer's charger.
Some of this is legitimate in that the manufacturer doesn't want to be on the hook for a warranty repair if the unit got damaged by a crappy charger. Much of it though is to force you to pay for their overpriced charger. Nonetheless, it is what it is.
Some third parties have gotten the specs or reverse engineered them for certain laptop brands, and you can by their chargers for much less than the laptop manufacturer's. Instead of trying to do what you suggest, it would be better to get a bunch of such laptop chargers that are compatible with your brand of laptop. They can usually be had for low 10s of $, so a small fraction of the price of the laptop.