Article ID : 00295002 / Last Modified : 11/10/2023Print

The art of charging: everything you need to know about phone battery life and charging

    The days of charging your phone for the upcoming week are long gone. As our smartphones evolved, their energy demands coevolved.

    Sometimes it’s all a bit confusing: do I charge all the way? Do I let my battery drain completely? And how come my phone charges more quickly with this charger and not the other?

    In this article, we explain the art of charging and go over some rules, tips and charger information. We'll even throw in how you can guess charging times based on some simple variables. Let's go!

    The six golden rules of phone charging

    1. The optimal battery zone (the Goldilocks zone) is to keep it between 20 and 80 percent charge: this is the most optimal charge for your phone's longevity.
    2. The charging speed of your battery will vary: the first and last 10 percent will charge more slowly
    3. Slow charging is better than fast charging for the longevity of your battery.
    4. Charging speed is decided by both your phone and your charger capability. However, your phone is the decisive factor: a phone will self-protect and only allow the maximum power to get in, even if the charger can do more. (That’s why some phones can’t use quick-chargers). 
    5. If you want to store a phone for a long time, store it at half battery capacity
    6. Wireless charging is, for now, always slower than charging through a cable

    How to calculate phone charging times?

    You can get a rough estimate of phone charging times with a few simple calculations. You need the following two bits of info:

    1. Watt. Watt expresses the output of energy, and it's mentioned on the charger. Unfortunately, it's not mentioned on phones. 
      • A current quick-charger can do 30 Watts per hour
      • USB 2.0 can output 2.5 Watts per hour
      • USB 3.0 can output 4.5 Watts per hour
    2. Milliamp per hour. It expresses the energy charge that a battery will hold and how long a device will run before the battery needs recharging.
      All our current Xperia phones have a capacity of 5000 milliamp/hour. You can also check this in the specifications

    To convert Milliamp per hour to Watt, you need to multiply the Milliamp per hour value times 4.2 (Volt). 

    It means a standard Xperia phone of 5000 milliamp/hour can charge 21 Watt/hour. 

    Calculation examples

    • 7 Watt charger → 21/7 = your phone will be fully charged in 3 hours
    • 21 Watt charger → 21/21 = your phone will be fully charged in 1 hour 
    • 28 Watt charger → 21/28 = 0.75 = your phone will be fully charged in 45 minutes

    How to use your Xperia as a wireless charger

    If your Xperia model has the ability to charge wirelessly, you can also use it to charge other devices. In short, your Xperia can act as a wireless power bank. 

    1. Go to Settings.
    2. Select Battery.
    3. Select Battery sharing.
    4. Now, put your Xperia with the screen facing down on a safe surface.
    5. Place the device or phone you want to charge on top of it. If it's a phone, the phones should be back to back.  

    Sony chargers and their capacity

    You can find charger information in the tiny script located on the charger. 
    You can use the Watts to calculate the average charging time. 

    Sony charger nameVolt & AmpWatts
    • EP800 (USB-A) 

     5V * 0,85A 

    • EP880
    • UCH20
    • EP850 (USB-A)

     5V * 1.5A

    • UCH10
    • (USB-A)

     5V * 1.8A


     9V * 1.7A 15.3W
     12V * 1.35A 16.2W
    • UCH12 (USB-A)

     5V * 2.7A

     9V * 1.8A 16.2W
     12V * 1.35A 16.2W
    • UC32C (USB-C)

     5V * 3A

     16 W
     9V * 2A 18W 
     12V * 1,5A 18W
     5V * 3A 15W 
     9V * 2A 18W
    • XQZ-UC11 (USB-C)
     5V * 3A 15W
     9V * 3A 18W
     15V * 2A 30W
     3.3V * 3A 9,9W
     16V * 1,95A 29,5W