Ask / Submit

Sailfish X (F5121) USB charging very slow [answered]

asked 2017-10-14 14:21:50 +0200

MystIsland gravatar image

updated 2018-12-17 11:25:11 +0200

rozgwi gravatar image

Anyone else having very slow charging when the phone (F5121) is connected to a computer?

If I charge the phone from the original Sony mains adapter, I get a current reading of about -1400 mA in the CSD Tool's Device Status. The battery gets charged in a normal speed.

When I connect the phone to my MacBook's USB3 port, I only got about -210 mA charging current. Which takes a very long time to charge. Also it seems to change by itself, now that I checked again it went down to only -16 mA (and then back to -200)!

The USB settings is set to charging only.

edit retag flag offensive reopen delete

The question has been closed for the following reason "the question is answered, an answer was accepted" by olf
close date 2018-12-17 13:00:21.557390


I test with Jolla1/Xperia and the same port/usb cable. - Jolla1 starts to charge and after 2-3min is getting -270mA - -380mA - Xperia starts to charge, then after 2-3 is getting -200mA - -220mA. After 15 minutes charging current reaches -340mA values.

molly ( 2017-10-14 15:15:57 +0200 )edit

you know that USB provides only upto 500mA - do you? You can try hook the phone to other device - perhaps the problem is not in the phone?

deloptes ( 2017-10-14 23:12:33 +0200 )edit

Yeah, but I was kinda expecting that modern phones would charge faster over USB... or at least closer to that 500mA.

In my case I think the problem was that it was charing at only about -20 mA and not higher. Hasn't done it again so it may have been just a glitch.

MystIsland ( 2017-10-14 23:21:35 +0200 )edit

You must deduct the current that the phone uses to function from the 500 mA. Therefore if the display is lit the battery could not be charging at all.

Giacomo Di Giacomo ( 2017-10-14 23:40:01 +0200 )edit

Same scenario here, when XPeria is low on battery and you plug it into a computer USB2 port, sometimes even my USB3 port isnt enough to keep the phone alive (let alone charge it); so its a wall plug, 15-25W Apple wallplug that does the magic 1-5Amps i think.

XFish ( 2017-10-15 08:54:58 +0200 )edit

1 Answer

Sort by » oldest newest most voted

answered 2018-12-17 11:23:28 +0200

rozgwi gravatar image

This is defenitely not a bug.

As mentioned by @deloptes and @Giacomo Di Giacomo, USB provides only a certain amount of current and you'll have to factor in the phone's own consumption.

Quoting from the Wikipedia article about USB hardware):

The limit to device power draw is stated in terms of a unit load, which is 100 mA or 150 mA for SuperSpeed devices. High-power devices draw at most 5 unit loads (500 mA) or 6 unit loads (900 mA) for SuperSpeed [USB 3.0] devices. A high-powered device must be configured, and may only draw as much power as specified in its configuration. [...] I.e., the maximum power may not be available.

So, depending on the port and version of USB you are using, currents may vary significantly. E.g. some notebooks may have hardware configurations that won't provide the full energy output specifed. Also, there might be energy saving protocols in effect.

As a side note: It's actually healthier fot the battery to charge at low currents. This will prolong it's total life span. The Battery University provides some useful info about properly handling Li-Ion batteries.

edit flag offensive delete publish link more

Question tools



Asked: 2017-10-14 14:21:50 +0200

Seen: 495 times

Last updated: Dec 17 '18