How to recharge a Power bank the right way?

A power bank is recharged through a USB charger or power adapter (just like a smartphone).

That is, connect one end of the charging cable to the Micro USB or USB-C input port of the power bank and the other end to the USB-A or USB-C output port of the charger.

In addition, the most current power banks – especially high-capacity models – incorporate the Qualcomm Quick Charge (QC) or Power Delivery (PD) fast charging protocol in their input port.

For this reason, we must differentiate between the 2 types of recharge that a power bank has:

  • Standard Charge: it is the conventional charge that has any electronic device with a USB port. It works with a voltage of 5 volts (V).
  • Fast Charge: it is a new charging system that works with a higher voltage (9, 12, or 20V). It requires the use of a compatible charger and cable to communicate with the charging protocol of the power bank.

Now, which charger should I use to recharge a power bank faster?

Ideally, for a power bank to recharge as quickly as possible, it is necessary to use a charger capable of supplying a power (W) equal to or greater than that specified on the power bank’s input port.

However, in practice, it is advisable to supply a higher power to prevent the charger from overheating and deteriorating in the long term.

Therefore, the first step would be to identify the maximum power allowed at the input port of the power bank:

Typically, in standard recharging (5V), the input port of a power bank usually supports maximum power of 5 watts (W) (5V/1A), 10W (5V/2A), 12W (5V/2.4A), 15W (5V/3A).

While if the input port supports Quick Charge (QC) and/or Power Delivery (PD) fast charging the power bank can charge at 18, 30, 45, and even 100 watts (W).

The following image shows the specifications of a 10000 mAh power bank:

We see that this power bank has 2 USB input ports and each of them supports a maximum power depending on the charging mode:

Port type Standard Charge QC Fast Charge PD Fast Charge
Micro-USB 10 W max. 18 W max.
USB-C 15 W max. 18 W max.

The next step is to look for a charger that meets the following 2 requirements so that the power bank is recharged in the shortest possible time:

  1. Its output ports can supply the maximum powers indicated in the table above.
  2. It is compatible with Quick Charge and Power Delivery fast charging protocols.

Remember that for QC and/or PD fast charging, it is also required that the charging cable is compatible with the protocol in question.

Normally, this cable is included with the power bank.

But, for example, if you buy a charger with fast charging and then use an old cable you have at home, then only standard charging will be activated.

Also, don’t forget other factors such as the length, cross-section, and condition of the cable, which will also affect the charging time of the power bank.

Here is a case study with a power bank analyzed by our team:

Case study: recharging a power bank

We will use the Tronsmart Trim power bank and a charger from the Ugreen brand that has the green port with Quick Charge 3.0 fast charging and the white port with standard charging (5V):

recharge power bank tronsmart trim

The following image shows the technical specifications of the Tronsmart Trim power bank.

power bank tronsmart trim specifications

These specifications show the type of USB input port: Micro-USB or USB-C, the charging voltages supported: 5V or 9V, and the maximum values of current (A) and power (W) supported by each port:

  • Micro USB Input: 5V/2A (10W) – 9V/2A (18W)
  • USB-C Input: 5V/2A (10W) – 9V/2A (18W)

That is, this model can be recharged in both Standard Charge (5V) and Quick Charge (9V) through one of its 2 available inputs: Micro USB or USB-C.

In the Standard Charge (5V), each port supports a maximum power of 10W (5V x 2A). Therefore, we should use a charger that has an output supplying at least 10W.

In our example, we will use the standard charging port (white color) of the Ugreen charger that provides a maximum power of 12W (5V/2.4A).

The Fast Charge (9V) system of this model can be performed using the Quick Charge 2.0 protocol through the Micro USB or USB-C port, or the Power Delivery protocol using the USB-C port.

To do this, we must use a charger compatible with QC or PD to be able to supply the power bank with a maximum power of 18W.

In this case, we can use the fast charging port QC 3.0 (green color) of the Ugreen charger that is compatible with previous versions of Quick Charge while for the Power Delivery protocol, it would be necessary to use another charger compatible with this technology.

In our tests performed with this model, the charging times obtained were:

  • Standard Charge 5V: 5h
  • Fast Charge QC: 3h 30min
  • Fast Charge PD: 3h 25min

Disclaimer: this video was translated using AI.

Can I charge a device while recharging the Power bank?

This function is called Pass-Through Charging and allows you to charge a device connected to the power bank while recharging.

Through the Pass-Through Charging technology, the Power Management Integrated Circuit (PMIC) of the power bank manages the energy supplied by the charger so that a part of its charge is transferred directly to the connected device.

Generally, depending on the model, some manufacturers give priority to charging the device as soon as possible, while others give priority to charging the power bank at the expense of reducing the charging speed of the device and even increasing the power of the charger, thereby overheating the power bank.

Regardless of how the Pass-Through Charging is performed, our recommendation is to avoid simultaneously charging both devices, as it affects the useful life of the power bank’s battery by spending more time recharging.

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