If a power strip has multiple USB ports, why can’t they all charge at max power at the same time?
In: Engineering
Most regular devices can’t function on a lower power draw and a higher one will short them out, and because of this each regular outlet in the wall and on a power strip need to conform to strict standards. Each device also has their own converter to handle changing from alternating to direct current with limiters setting the voltage and amperage to exactly what the device needs. But these aren’t smart converters or anything so they need that rigid consistency I mentioned. It’s also why each outlet on a strip is in parallel so that another device doesn’t cause added resistance and drop power draw down the line.
USB charging devices, on the other hand, can handle varied power draw up to a certain amount that is typically far above the standard regular or fast charging USB port standard. You still need to convert from AC to DC current. The power strip has a built in converter, but making small, efficient converters is expensive. To save money, USB power strips have a singe converter that converts to a set voltage/amperage (the normal or fast charging standard) and runs along the entire set of USB charging ports. Since USB charging can handle such varied power within allowances, there’s no risk to the devices. And since they’re all sharing the same line of electricity, each device has to share if there’s more than one plugged in.
So back to your question, why can’t they just put a bunch of converters in, one for each USB port, and have each converter in full parallel? Well… They can. They just don’t, because they’re cheap.
TL;DR because the manufacturers are cheap.
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