– Why do electric devices with batteries (phones, electric cars, …) can only be charged by one charger at a time?


Hi, with all the boom of “fast charging” I’ve been wondering why can’t we have phones or electric cars with twice or more the charging ports. I understand that is inconvenient to plug two chargers instead of one but wouldn’t that increase the charging rate, solving one of the problems with electric cars (refueling gas is way faster). As this is not the case there should be a good reason why it is not feasible, what is it ?

(I did not find anything close to convincing in google).

In: Engineering

The limitations are rarely the charging connector itself. USB power delivery supports 100 watts over the USB-C connector if the appropriate hardware was installed into the device being charged (and an appropriately electrically marked cable), although for a phone such a charging rate would probably be very unsafe for the battery being charged.

For electric cars you would probably also have to seriously consider how that much electricity would be delivered to the charging dock.

Cant say something sensible other than: they’re all one circuit. And there are probably reasons why it’s hard to make it into several modular circuits for multiple chargers. Plus, the heat. Charging creates massive heat, that’s why some cars use liquid cooling on their battery packs. That needs to dissipate somewhere too, without your phone becoming too hot to handle…?

The problem is that faster charging wears down the battery quicker. They want them to be able charge quickly but not damage the battery in the process. They could put more power in one port but they limit the charging speed to limit heat and degradation. Two ports wouldn’t make any difference.

Better to just divide the battery into two, and pull twice as much current from a single cable to charge both cells in parallel (which is how it is done already, but many more cells than two).

It’s fairly easy, to engineer a faster charging port – just add more (or larger) conductors to carry more current, and crank up the voltage. A single charge cable can supply plenty of power.

The problem, is that all of that energy needs to get into the battery. And the battery can only handle so much energy at a time. Add too much too quickly, and you might accidentally overcharge the battery, or you might overheat it. Both of these will damage the battery (and by extension, possibly the device and surrounding environment). So, charging a battery (or set of batteries) is a complicated endeavor that needs to be done carefully, and the batteries themselves need to be designed to charge quickly, which isn’t trivial, and won’t work for every application. (Tesla, for instance, has special heaters and coolers to keep the battery at the right temperature for charging.)