Librem5 does not charge through Nexdock360

When my L5 is connected to my Nexdock360 which by itself is connected to the L5 or Nexdock usb-c power converter the phone discharges slowly without any usage beside the screen being switched on.

I measured the power draw of both converters in different situations and found that a tablet charging can make them draw about 16.7W (both the same). This is the maximum I saw.

L5 fully charged, screen on, idle: 3.6W
Nexdock360 fully charged, screen on, nothing connected: 6.5W

I’d expect that both connected together still could draw enough power to make the battery of the L5 charge. But

L5 28% battery, screen on, idle + Nexdock360, fully charged: 13.8W

The battery of the L5 is in this scenario slowly discharging by a little more than 3% per hour.

Do I have to use a different power converter even though the ones I have could deliver more power than being used by the combination?

@Kyle_Rankin, did you observe the same behaviour while using your N360 + L5?

I’d like to have a situation where I can dock the L5 to the N360, use it, while charging it at the best rate possible. Any suggestions?

P.D. L5 does also slowly discharge when connected to the N360 running on battery power…

P.P.D N360 battery recharging + L5 docked, screens on, otherwise idle: 18.9W - highest power draw observed so far

This all - in my opinion - is pointing into the direction that my N360 cannot deliver sufficient power to the L5 for some reason.

Behaviour doesn’t change when I use a different cable between L5 and N360.

P.D. Just found this information saying the N360 can deliver 5V/1A = 5W to a connected device. Shouldn’t this be sufficient to run the L5 without discharging?

I would have thought so, yes. There’s a heap of information available to investigate this though. Refer other topics about charging.

I’ve found it depends on what the phone is doing. I haven’t sat there with a power meter measuring draw like you have so my experience is just anecdotal. Whether 5W is sufficient to run and charge a L5 with a screen on likely depends on what the phone is doing. It does take quite a bit more power for the L5 to drive an external display, especially when I’m also using it for things like watching videos. I also don’t necessarily have the L5 screen at full brightness.

I suspect it’s the kind of thing that will continue to improve as we find more efficiencies in power management during active use. This is another reason why it’s important to continue to improve running power consumption as well as also improving idle (through suspend). It’s why running power consumption was our initial focus instead of focusing on suspend and while we have made a lot of improvements in that regard over the years there is still further room for improvement.


Is there still room to improve this behaviour?

My experience is that when connected to the nexdock360 the L5 heats up with running no program at all (except an sshd with one connection and a shell).

I used upower to measure the temperature. I connected the L5 to the N360 with something around 35% of battery left and a battery temperature of 34°C.

Within ten minutes the temperature rises to 45°C.

P.D. After working for 30 minutes on the command line via ssh the temperature is above 51°C and the red led starts blinking.

dmesg contains the message

This is why. Because the battery was quite low, the L5 was drawing a lot of power to charge itself in addition to all of the extra power it was using to drive the display. If you were to query the battery you’d probably see that a lot of power is flowing through the Librem 5. This is in the interest of charging as quickly as it can safely, with the tradeoff being more heat. If it happens to get too hot in the process it will scale that down and blink that red LED. As it becomes more charged it starts drawing less power, which results in less heat.

I don’t normally run into the situation you are describing, but I also normally am docked when my Librem 5 already has quite a bit of power (90%+). I normally don’t rely on the dock to charge my Librem 5 when it’s in a state of discharge, but just to try to maintain whatever charge it happens to have.

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Maybe this needs UI to allow the user to choose the charging profile. It may be that, when connected to a dock, the user is not in quite such a rush to get charged e.g. may be planning on staying docked and charging for many hours.


Would there be a way to lower power consumption for driving the external display via software improvement?

Is there a way to limit the power usage of the cpu/gpu to make sure that the phone charges or at least does not discharge?

Lower cpu/gpu-power, but infinite runtime connected to the nexdock360…


I’d recommend lowering the frame rate and/or resolution. That should bring some benefits.

I do not have a way to measure the usb-c power directly. But if I measure the power drawn by the L5s power adaptor I can see a difference around 0.5W between 60Hz and 30Hz for the screen of the N360. That doesn’t seem to be much.

Is there software that still can be optimized?

Are there features planned to make it possible/easy to set a preference like “charge as fast as you can even if the phone is slow”, “optimal performance without discharging the battery” and “best performance”?

Meanwhile I received a baseus dock 8-in-1 (the one mentioned in the compatibility list) and as far as I can tell with not using it too much it does charge the L5 while it is connected to an external screen and keyboard.

Even better: I connected the L5 to the dock and the dock via hdmi and usb (keyboard and touchpad) to the nexdock360. This seems to work as a stationary setup and the nexdock can be charged and switched on/off separately from the L5.

Maybe @dos knows.

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There are still things to be done in order to make using L5 with external screens more efficient. Compressed buffer formats will be one thing that should reduce memory bandwidth significantly, another one is TS buffer sharing, which is already in works:

When it comes to charging, the thing is to have peripherals that can provide enough current at 5V. I’d say that you need at least 2A to charge when using an external screen, and having 3A would give a comfortable headroom - that’s what Baseus dock negotiates here for me.


It is now definitively and openly/honestly answered that 5W isn’t enough power (between 12W and 15W needed) to charge Librem 5 battery when this Linux phone connected to N360:

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@ChriChri, perhaps following setup might help you (where Device 3 would be your Nexdock360):
Rest of this idea is, sort of, explained here: New Setup for 3 Computers Hardware.

Do I understand you right:

  • Device 1 = Librem 5
  • Device 3 = Nexdock360
  • Device 2 = very powerful charger

Video/usb-data gets routed through the “magic device” between Device 1(L5) and Device 3(N360) and both devices draw power from Device 2(very powerful charger).

The “magic device” in the middle talks to “very powerful charger” using PD to get the power specs and tell the charger what it needs and each of the devices N360 and L5 talk to the “magic device” to tell it how they’d like to be provided their power.

Did you try this and is is known to work?

I looked for such a device (I searched for something like “usb-c power injector pd”) and didn’t find anything.

My actual solution attempt is described above:

Baseus usb-c dock connected to:

  • power adaptor (feeding dock and L5)
  • usb-c: keyboard/touchpad to N360 port (left near screen)
  • hdmi: video to N360
  • ethernet: local network
  • usb-a: external mouse

N360 draws power through a different usb-c connection from a second power adaptor.

Seems to work for a desktop setup, but the “magic device” would need a lot less cables.

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That would be original Librem 5 power supply.

No just Librem 5 would draw power from the connected power supply (although I’m not familiar with N360 at this moment).

Sorry but no. I do not possess N360, but still it would be nice that you try this (for the rest of us to be aware if indeed helped), just thought of mine that this “magic device” might be the one that you need in between this combo (and solve this Librem 5 charging issue).

I’ll try and let you know. Found the “magic device” at a reagional dealer so that’ll be easy to return it if it doesn’t work like expected.

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Is it not just a powered USB C hub?

If so it wouldn’t work as expected. It needs to pass through the hdmi signal, also. Furthermore it’d need - as I understood the PD protocol - to intercept the data traffic to deliver meaningful PD information to all connected devices.

Maybe someone with more inside in PD can fill in some knowledge here and correct my simple or even wrong description?

Setup, as I understand above screenshot, for related “magic device” (Device 3 = Nexdock360) should be the very same as shown here (there exist only one USB-C port on N360 that supports DisplaPort, yet please correct me if I’m wrong):

Second option for the same Device 3 = Nexdock360 would be USB-C to HDMI Adapter (for example:, actually both related ports that you plan to be used with this “magic device” are placed on the left N360 side.

And, as hopefully clear from the screenshot above, only device that would get powered from is Librem 5, getting power from its original power supply as 5V/3A. Charging USB-C port for Nexdock360 is on the right side of this device and I have no clue which voltage/power it consumes, as those numbers probably quite irrelevant here, IMO.

Sorry for this late reply! EDIT:

Baseus GN16A dock USB Type-C female port (entrance port for 5V/3A or feeding port) you can still connect to the bottom right side USB-C data port of the N360 and continue using it with the rest of there connected devices (minus Librem 5).