The rivalry between Alternating Current (AC) and Direct Current(DC) dates back to over a century, the time when electricity was first used to power devices. I was recently inspired by this article on why DC will be the way forward. According to the experts’ opinion in the article AC-DC conversion cycle results in an electrical power loss of close to 15%. (Read the complete article to know why solar power could be the answer for the future).
Everyday gadgets are all made up off transistors which require Direct Current for functioning. Batteries which power your phone,ipad, ipod and other tablets provide DC and they in turn are charged by DC. However, when you use an adapter to charge your devices via the electrical socket, you are drawing AC and converting it into DC and then charging the battery. This conversion results in power loss. Advancements in tech and increase in the number of portable gadgets have resulted in using a common connector to charge the device and USB has been the choice of the commons. Universal Serial Bus aka USB channels DC in devices.
So why use your computer USB port rather than a USB conector and plug it in the electrical socket?The answer lies in the way computers are power. All computers are powered by Power Supply Units (PSU) that take in AC and deliver DC to the computer buses , which in turn is connected to the devices on mother board. The USB socket in the computer gets Direct current from this conversion in the PSU. When you charge your gadget by connecting through this USB drive you are not adding up the AC-DC conversion loss.( Read this article to know more about USB charging).
Isn’t the total power consumption same, irrespective of whether I charge my device through USB or rather connect it on the wall socket?
Mathematically adding up connected load would result in a scenario of a=b, however electricity isn’t such a concept. Regardless of whether your USB socket in the computer is connected to a device or is left idle there is a standby consumption that is encountered. This is accounted by the sum total of performance efficiencies of all other devices on the PSU resulting in a variation of the efficiency of the PSU. This means the total power consumption can be less than the sum total of all devices connected.( Check this post to see the variance in power consumption and efficiency of the PSUs).
So, the next time you want to charge your gadget, remember USB connection through the computer is the way to do it. It all counts because energy saved is energy produced.
Mission Shunya 