That’s not a problem at all; in fact, that’s a normal, wanted and expected behavior that’s well within the tolerance ranges (and it can change depending on load, cable resistance and temperature anyway).
Doing PD 2.0 with 5V/3A and USB-C DisplayPort alt-mode should be all you need. Other than that, we’re entering a territory of incompatibilities because of bugs and protocol violations, so it’s hard to say more without doing tests with an actual device in question.
Thank you for this reply! We really needed to get this very straight/relevant answer.
In addition, yesterday afternoon I just received Anker PowerPort Atom PD 2 with GaN (A2029), heavy duty power supply that looks like it might be the perfect match for both Librem 5 and Librem 14. Cannot say more at the moment but my first impression is that this A2029 doesn’t overheats Librem 5 at all (please read again: just “impression”). Secondly, just by pressing the power button to turn the screen off voltage jumps from 4.948V to 4.998V (and now 5.00015V), this behavior is repeatable (indeed very fine/quiet calibration), by having battery currently at around 80%.
Also, as expected, both USB-PD ports react the same on the same type of load. And those two USB-PD ports are the same ones reused for the Anker PowerPort Atom PD 4 (A2041), and therefore with max. output of 60W. @dos please let me know if there is something that I might/should check (some specific CLI request that I should type toward Anker A2029 as source, perhaps within next week, if not stretching myself to make few photos even today) with this Anker 60W A2029 power supply, while it functions on top of Infineon Technologies CYPD4225-40LQXIT [“Notice regarding compliance with Universal Serial Bus specification. Cypress offers firmware and hardware solutions that are certified to comply with the Universal Serial Bus specification, USB Type-C™ Cable and Connector Specification, and other specifications of USB Implementers Forum, Inc (USB-IF)”]?
Furthermore attaching here three pictures just to show that Anker 30W A2017 indeed supports 20V⎓1.5A but this on the edge “support” needs to be taken into account only if about to power on and off some 30W or rather 25W blinking light and not any laptop battery (as currently my laptop battery at 60% taking out (needs) 20V⎓2A:
You need PD as only with a negotiated PD contract DisplayPort can work. But as was written above you usually can’t see from the labeling how much power it will provide. Once a PD contract is negotiated DisplayPort should work given it’s within the L5s spec (which is driven by DCSS capabilities).
I prefer Anker A2029 over Anker A2017 (compact size isn’t necessarily my preference) several times. So much liking it that already took second place on my power supplies ranking 
, those that support only USB-DCP protocol at 5.00V.
@angus.ainslie, @dcz, @dos, @guido.gunther, @joao.azevedo, @mladen, big thanks to all of you that work and contribute a lot toward further development/improvements of the Librem 5! Thanks Purism Team!
@dos, yesterday (just sharing this with you) I found official usb.org document telling myself (non-expert) that Librem 5 “definitively” and officially complies with what presented inside of it:
Therefore please take a look at slides five and six, at least, within this presentation:
And, making above short:
CDP (Charging Downstream Port): A USB port with enhanced charging capability, it has USB data transfer and can supply a maximum current of 1.5 A to the BC1.2 portable device.
DCP (Dedicated Charging Port): A CDP without USB data transfer, it can provide 4.75V~5.5V and 1.5A charging current to the BC1.2 portable device, and the DCP will connect the resistor R across D+ and D-.
Both above definitions belong to the GRL Team: https://www.graniteriverlabs.com/hs-fs/hubfs/1-10-768x240.png.
Thanks!
@dos what about powering-BC.1.2 to docking station connected L5? I seeing many issues with Power Delivery and Dock.
Tested bc1.2 with dock it do not worked.
I tested BC1.2 and with Suspend-to-Ram this worked good.
I don’t get the question. If there’s a docking station in between L5 and power supply, then L5 is not involved in any negotiations with power supply at all - it’s only concerned with the docking station, so whatever happens then depends on the station’s firmware.
If someone wonders on how I “know” (before connecting anything to the USB-C port of Librem 5) that chosen power supply will charge my Librem 5, take a look below when recharging some 18650 3000mAh 3.6V based device maximum (1.880A) allowed/accepted load (another 18650 battery might allow higher charging amperage but this would be anyway irrelevant here):
When using device that can indeed take/consume 3.0A at 5.00V:
Very same 5V/3A “end user” (where actually PD 20V recharging preferred) with another 56 kΩ compliant/premium cable used:
Power supply used for this demo is described here: Changes in charging behavior ?!. 12V was connected/used input as my preference here, but 20V input might be used/implemented as well.
EDIT: I’m not using here related powerbank (as having another purpose) with the Librem 5, but anyway (as mentioned above) showing USB-PD port related 5V/3A input (to be clear, as shown above, about here related/presented power supply, from Wondom, max. current output):
Below picture is showing power receiving data from the USB 1A charging port (black one), might be as well the recommended, supported protocol described here, one to be used with …:
I have no additional comment (nothing new to add to the one of my recent posts, last three pictures attached actually):
In addition @amosbatto, below shown power supply might be recommended for any docking station USB-PD port (Librem 5 charging related), yet not preferable from my side (therefore this attachment, to show quite usable power supply that is not my primary choice, while somewhat disappointing “upgrade” done, in terms of supported protocols) for the direct charging of the Librem 5 battery (up to the 5.00V preference of mine), here shown quality brand replacement (looks like it extends powered on usage as well) battery:
EP-T4510 is the first GaN charger made by Samsung. And it is also the first power supply, that I see, carrying USB-IF Logo:
P.S. I do not have one, but owners of EP-T4510 (or even EP-TA845) are very welcomed to provide their USB-DCP fast charge protocol tests here in this thread (just while both of those Samsung power supplies are indeed lacking quite interfering Apple 5V, either 2.4A or 2.1A, charging protocol).
Nice charger the bad it is only 45w maxx. usb-if logo it is very import on p.d charger and cable. I would like buy it.
With its 20V⎓2.5A based on GaN (lower charging temperature) and by having Dialog iW9801 as primary-side controller, that provides advanced zero-voltage-switching (ZVS), and having built-in Dialog iW709 as secondary-side USB PD protocol IC, might be just about enough size/speed even for your Librem 14, hopefully 
(although if 45W enough power depends on the job done there). Short description is here: https://www.how2power.com/pdf_view.php?url=/newsletters/2108/products/H2PToday2108_products_DialogSemiconductor.pdf.
P.S. I’m not recommending EP-T4510 directly, but if you (or someone else) make charging test(s) with the Librem 5 (as I believe that this technology have some advantages) I’d appreciate.
As you somehow (while I needed some time) encouraged myself to test further 5.20V voltage with my Librem 5, finally I did this:
@dos, thank you very much for everything you do for Purism!
output of my own above 5.0V charging voltage focus (as long as I’m not getting some interfering/disturbing electromagnetic frequencies/ripples). And, this is not my permanent nor recommended charging setup (although running it non-stop with my very first Librem 5 phone for several days now).
@irvinewade, as I was very lucky and as I mentioned in my original post here, below PD USB-C 15W power supply (SB-AC16-TCUS) is still the one of my very favorite power supplies for charging of the Librem 5 (therefore I’d never ever sell it away):
Could you please show a better photo of the device itself or a pointer to the manual etc. Thanks
I cannot say much other than it was from some old stock (and that PHIHONG TECHNOLOGY CO. is well known manufacturer):
EDIT: Google actually bought TC G1000 from Phihong (for their Pixel smartphones) and when I get more time I might make some review of this power supply charging Librem 5 (if any interest available). This is indeed one of the best and most reliable PD power supplies for charging of the Librem 5 (up to my own expectations/approach 
).
As published two days ago, quite useful disassembly (only pure DCP protocol output registered, please refer to the related picture for reference) of brand new Lenovo联想10W充电器MC-108.
