FP4 slow charging via USB


since an hardware upgrade from a 10 year old mainboard with USB 2.0 to a mainboard with USB 3.1 (2. gen) I steppt down to “slow charging” plugging in my FP4.
With the old system I at least had “normal charging”.

Has anyone experience with this issue?
I mean, should it be even possivle by now to “speed charge” a phone via USB?

Thanks in advance,


This is an answer I received in the e.foundation-forum:

Your FP4 has a USB-C 3.0 socket, your PC has USB 3.1, which is downwards compatible. However, USB 3.0 and 3.1 only work with USB cables which, in addition to the previous data line pair (D+/D-), require a separately shielded pair of wires (shielded differential pair, SDP) for both transfer directions and a common shielding of the entire cable in order to comply with EMC limits.

USB-A 3.0 plugs can be recognised by the blue inner part. The cable and plug are often, but not necessarily, blue in colour. The USB 3.0 connectors have five additional contacts, whereby the type A plug is compatible with the old USB sockets. In the type A plug, the new contacts are located in the area where there is only plastic in the old plug.

USB-A 3.0 blue

Also note the following:

Default PC-USB-A 2.0 Power = 5V | 500mA (= 2,5 W)
Default PC-USB-A 3.0/3.1 Power = 5V | 900mA (= 4,5 Watt max. power output)

Fairphone 4 Dual Charger:
QC 3.0 USB-A 18 W max power output.
QC 3.0 USB-C 30 W max. power output.

The USB-C cable for the FP4 must also be able to supply 2.6 amps or 4 amps max. of current.

Qualcomm® Quick Charge™ 3.0 Specifications
Maximum Input Voltage: 3,6V to 20V (200mV increments) QC Mode
Maximum Current: 2.600 mA or 4.600 mA QC Mode
Power output max.: 36 Watt

Therefore, try a (premium) USB-A 3.x to USB-C 3.1 cable. This will not only give you significantly faster data transfer but also faster charging.

There are also USB cables that are only suitable for charging, but not for charging + data transfer.

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Have you tried a usb 4 cable with an type-A male to Type-C Female adapter. That combination of cables had improved performance by about an hour less of charging time. That’s my experience however. I to have noticed that there is no fast charging option in the battery settings menu for the FP4. Maybe a new cable can help you in this situation.

You don’t need a USB 3 cable for fast charging. But as you mentioned yourself, a USB 3 port provides a maximum of 4.5 W. Considering the FP4 supports 20 W charging, I’d say that’s pretty slow in comparison. So there is nothing strange here.

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I think she is referring to the watt output. Most cables today can support the amount no problem depending on if your charger, Cable and any adapter supports any form of fast charging. But after reading it again I think she wants a slow charging cable for passive charging. There is cables that have older standards still out there that would charge it slower. You just have to find a usb 2.0 cable. The only other thing to consider is qi charging adapter and charger for the same effect. But of course I’d could be mistaken after re-reading this thread. Sometimes tech specs is confusing to say the least. There are to many things to consider. When picking a product there is always a catch. Like the type of display or graphics card for PC Gaming as an example. People like having high FPS and response times instead of higher resolutions in the type of monitor they intend to buy. It’s not like the company gives you a spreadsheet with a list of Specs on it. You normally go by reviews and what is on the box with something That says Utra HD or 120Htz. A few years back it was 4k at 30fps for a 60Htz monitor. It just doesn’t make sense when I paid for a TV expecting 4K At 60 FPS for Xbox Gaming at The Time. That’s my experience and a story that should explain why I’m confused. I think she wants to slow charge it to preserve the battery if I’m not mistaken.

Ok I have finished now my testing and reading and I solved the mystery:

Old Asus Maximus VII gene (with ASMedia 3.0 USB Ports):

1100 mA charging no matter which cable I use.
(Works only on the ASMedia port, because the board has Intel USB 3.0 ports, too but there I charged with 400 mA)

New Asus Prime Z790 M plus:

  • 400 mA charging with old cable
  • 800 mA charging with new premium cable

So I am gonna ask the Asus support If there is something else I can do to increase the charging capability.