Fast charging is one of the features of mobile phones. You don’t know what you need until you find yourself in need.: That day when you leave the house and realize your battery is red, your battery is dry, and you plug it in for a few minutes.

You probably already know that there are various technologies and that it is a matter of Watts, more specifically Amperes and Volts, but fast charging has a very specific way of working, especially in the opening minutes.

How fast does charging work over time on a mobile phone?

Whatever the standards of the brands, there are inherent minimums in the lithium-ion batteries themselves, which we will find not only in phones but also in other devices that integrate them. So the battery operates at a certain voltage and can take and release a certain amount of current. More voltage and more density directly correlate to more power [recordemos la fórmula de física del insti, potencia (Watios) = voltaje (Voltios) x intensidad de corriente (Amperios)].

However, batteries have strict limits on their operating limits, especially regarding voltage, which must be adhered to for safe charging and therefore optimizing the service life of the component and device. fast charging it’s not a simple thing apply high tension and intensity The more the movement seeks, the better.

Charging the battery is divided into two stages differentiated: Constant current density and constant voltage, which you can see below these lines, as you can see in this graph from Battery University.

For ease of understanding: the red line corresponds to voltage, the blue line corresponds to current density. to look how the voltage changes during chargingbecause this affects the amount of current that can be delivered to the battery. We are particularly interested in the initial phase, the direct current phase, because this is the key to fast charging in the first minutes.

Fast charging technologies take advantage of this constant current phase to deliver as much current as possible before the battery reaches its maximum voltage. Like this, They are more effective when the battery is discharged (less than 50% of its capacity) and has an increasingly smaller impact on charging time when exceeding 80% of capacity.

In fact, the constant current phase is the period that causes the least damage to battery health in the long run. Or in other words, higher constant voltage combined with heat is what degrades the lifespan of the component the most.

From here there are different techniques manufacturers can apply. Increase the energy management capacity of your batteries to improve loading times. For example, using more advanced materials to withstand higher currents and temperatures, using batteries with multiple anode and cathode tabs to reduce internal resistance and therefore increase their current, dual-cell batteries split the current into two batteries in parallel.

Optimizing battery charging time also includes monitoring voltage and current. debugging algorithmsbecause this data, in addition to the temperature, can be sent to smart chargers to adjust the device’s power supply.

Cover | Samuel Fernández for Xataka Móvil

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