Watts up with Wireless Charging – Stop making this wireless charging mistake today.

This article intends to deal with some common troubleshooting questions we hear all the time about Qi Wireless Charging:

  • Why won’t my phone charge through the case?
  • Wireless charging not working with my iPhone?
  • iPhone 12 Wireless charging not working?
  • and more…

Firstly, what is Qi – Qi is the common standard for wireless charging. Qi is actually a Chinese phrase pronounced ‘chee’ and means literally ‘energy flow’. Some people refer to wireless charging of smartphones as Qi charging, NFC or wireless charging. All in all it is the exact same thing.

If you have a wireless ‘Qi’ charging enabled smartphone, there are a plethora of charging pucks, pads, desk pads and in car chargers to choose from. This is where it gets a little more complex.

Depending on device, your smartphone will be restricted as to the amount of power it will take at one time. Most iPhones for example are limited to 7.5W of power input which dictates the speed the devices will charge. Some Samsung devices will take 9W of power which results in faster charging, iPhone 12 can take 12W of charge for even faster charging.

Adding distance between a device and the charger diminishes the power transfer which can cause a device to not charge at all or slow the power transfer. Ensuring a commensurate power source to the charger will ensure sufficient power is being transferred to the device to make up for the additional distance.

The common mistake

The humble plug. If you own an iPad and an iPhone, you may have used your iPhone USB plug ‘5W’ to try and charge your iPad and you would have noted the charge symbol is signalling connection but the percentage drops over time, what gives?

The power the iPad uses is greater than the power that can be accepted by your iPad through a 5W plug, the same is true of Qi charging. Matching the right power plug to the right charger, depending on how you want to use your device is crucial and commonly overlooked.

For basic and slow charging, a 7.5W Qi charger could possibly charge your phone very slowly if you are connected to a laptop or other device or even a 5W wall socket plug due to the weak power input to the charger. If you add a case or cover, this is likely to either stop completely, fail to connect or signal a connection but lose battery percentage due to the extra distance the power has to travel.

Using a 10W+ plug on the 7.5W charger will ensure that the full 7.5W of charge will pass to the device and thus making charging much more stable.

Here at TORRO, we recommend a minimum of a 12W charger (ideally 18W) and it is crucial that a 12W plug is used. It is important not to connect the charger with a laptop or other USB device, certainly not an old 5W iPhone plug which may be found around the home.

A decent 12W wall plug is required to provide the full amount of power needed to ensure the charger emits the full 12W of charging power so the device can receive sufficient charge, even through a case. The higher the wattage the better and faster the charge.

For Apple MagSafe which can emit 15W of charge to an iPhone which can take 12W of power wirelessly. The official advice from Apple is for a 20W plug to be used even when the phone has no case attached.

We tested the MagSafe charger on an iPhone 12 with a 20W plug and it chargers fully through the range of TORRO premium leather cases. For MagSafe magnetic connection, please check style and model for compatibility.

How to find what plug you have?

UK USB Charger Safety Info

Knowing what plug you have is very important but the labelling that manufacturers use on their plugs can be very different to the information provided by the accessory makers. Often the plug manufacturers display the information in "Volts" & "Amps" where as the accessories always ask for "Watts". So how do you find out?

Mathematically: Watts = Volts x Amps

Common Examples 

Volts / Amps Watts
5 Volt / 1.0 Amp 5W
5 Volt / 2.0 Amp 10W
5 Volt / 2.4 Amp 12W
5 Volt / 4.0 Amp 20W
9 Volt / 2.0 Amp 18W
9 Volt / 2.22 Amp 20W
9 Volt / 3.0 Amp 27W
12 Volt / 1.5 Amp 18W
12 Volt / 3.0 Amp 36W
15 Volt / 3.0 Amp 45W
20 Volt / 3.25 Amp 65W

This is not an exhaustive lists and there are many other Volt/Amp combinations in use.

Caution when purchasing multi-port chargers

When purchasing a multi-port charger (a plug which charges 2 or more devices), take extra care to check the output of each port as many manufacturers will tell you the total output of the device which isn't always achievable from each USB port - which can be very mis-leading.

Also be aware when purchasing chargers which include both USB and USB-C ports, as the there are some cases whereby the total output of the USB-C port is reduced when you use the standard USB simultaneously.

Other examples, include chargers which are advertised at 12W and feature 2 standard USB ports, but the total output is actually shared between the two ports (6W each) rather than each port outputting at 12W. Again, easily overlooked!

In Summary

If you are struggling to power your device with a wireless charger with or without a case on the device, please check the wattage the charger is capable of outputting, 12W or higher is the modern standard (18W becoming more common) for newer devices, we recommend a minimum output capacity of 12W and please ensure you are connected to a wall plug that can transmit the full 12W of power, going higher is better to ensure you get the full power from your charger.

Newer devices such as the iPhone 12 work to different power acceptance standards to older Qi devices therefore the old standard of 5W and 7.5W chargers will not be as effective on newer devices - if at all.

Having your car engine running may also impact your in-car, in-built charger. Check the spec with your car dealer.

As an illustrative guide, please see the short video attached.

The first charger is a 7.5W charger with a 7.5W plug, it fails to charge the new iPhone 12 Pro.

The second charger is a 12W charger with a 12W plug to power it, it charges the new iPhone 12 Pro perfectly and quickly even through a case.