For me this makes no sense because Librem 5 can work without battery if it gets enough power. So for me the goal is that it runs without using the battery when in convergence mode. If the battery is kept charged and bypassed then the battery will heat less than if it constantly discharges/charges, or am I wrong?
This is also my motivation why I want to get as much as possible power through the dock to Librem 5. So that it gets enough without having to suck from the battery.
I think you might have misunderstood. I am asking about the lowest possible voltage to charge and still use the device.
Charging with high voltages and amps directly correlates to heat. That is how power regulation, etc. works.
I would rather trickle charge overnight, and not overheat doing it, than overheat during a more rapid charge.
I’m asking if such a thing is feasible.
I am definitely curious to learn about the consumption of Librem 5 if you want to run it without any limitations and without a battery. But honestly I doubt that it consumes so little energy.
Raspberry Pi 4 requires a 5V 3A power supply and when using less power you get a warning message, that the system gets too little power and this could cause data loss.
Do you believe that Librem 5 with LTE modem and WiFi is going to consume 6 times less or even twice less? I doubt it. But this would be very very very interesting to find out.
I have no idea how much the SoC and additional components consume, hence why I am asking here.
It is also why my question is still a legit one. Hope that makes sense.
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Take the battery out? 
I think if you want to prioritise running the device and not charging and the battery level is low enough that it would charge if the Librem 5 is receiving power from the USB-C port then you would have to override the default behaviour with magic incantations.
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Let us say I take the battery out and use a dock set-up that delivers 5V 1,5A like the maximum achieved in the tests of Quarnero. Will Librem 5 warn me that it does not get enough before some damage / data loss occurs?
I don’t want to damage the device.
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I don’t know but I doubt that any damage would occur. 1.5 A should be more than enough to run the device anyway.
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How do you judge that 5V 1,5A would be enough?
I compare it with Raspberry Pi 4 in my head.
Librem 5 has a display while RPi doesn’t.
Librem 5 has an LTE modem while RPi doesn’t.
Librem 5 has a WiFi module that is not part of the SoC and is more capable than the built in WiFi of the RPi which does not necessarily means that it needs more power, but I GUESS it needs.
At least because of these 3 factors I would GUESS that Librem 5 needs more juice under average load and under full load compared to average load and full load of RPi4.
It would be nice if we had an official statement on what is sufficient for running Librem 5 without a battery and for example for a hot swap of the battery.
On the other hand, the raspberry pi has a bunch of ports and pins it has to provide power to that the L5 doesn’t. It isn’t out of the question that it would require more power.
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You are having right as, IMHO, having lower voltage and lower amperage during charging keeps overheating down (actually there is none). 4.8V/1400mA might serve as some orientation, especially when battery already above 50% (anything negotiated above 5.00V I actually and simply do not use), therefore I’d recommend using power supply (or power bank) providing 5.00V/1700mA, at least (actually cannot confirm or have no evidence that more than 5.00V/1900mA needed with the Librem 5, for any usage, although I recall seeing bursts with over 2.1A). With screen off (please note that Wi-Fi is not on, not consuming any power, therefore it is already achievable to have Librem 5 on standby with under 5.00V/0.2A, another guess of mine as just do not have time to proof this, but things are already looking good to me anyway):
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If you turn off the L5 and plug it into the charger that came with the phone, then the L5 will trickle charge at 5V x 0.5A (2.5W). If you turn on the phone and plug it into a USB 2.0 port, then the current will also be 5V x 0.5A (2.5W), but the battery hardly charges at all at that level of current when the L5 is turned on, so I assume that all the current is being used to operate the device.
If you want to trickle charge the L5 while it is turned on, I would assume that you want it to use 5V x 1.0A (5W), because the L5 reduces the current to that level when it gets too hot while charging and the status light starts blinking. However, I don’t know how to manually set the charging level.
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I would not assume nor try to use any power supply (charger) with max. output of 5V/1.5A or less (5V/1.0A) because those will overheat within relatively short time and probably catch fire ASAP (it might all of a sudden turn into very dangerous game). Please avoid such experiments if not familiar with power supply in usage, rather use compliant docking station in between of … or at least consider usage of at least 3A compliant converter (if about to reduce, from higher value only, power supply provided current for some purpose that is not supported officially): https://www.assmann.com/product-pdf/4016032468707?PL=en.
Again, please recheck twice which power supply connecting toward any smartphone and confirm your expectations with the expert opinion/address (open other relevant review, many very relevant ones present there):
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My idea was to change a setting in the L5 to change the charging level to 1.0A, but as I said, I haven’t investigated how to do it.
Yes, any charger can be dangerous, if the L5 tries to pull more amps from the charger than it is designed to output, so people who are experimenting with other chargers should be monitoring the amperage to make sure that the L5 is negotiating the correct amperage limits with the charger. In my tests with other chargers, I watched the amps using a USB multimeter and checked the surface temperature of the charger to make sure it wasn’t overheating. I tried several different chargers with the L5 that were limited to a max of 0.5A, 2.0A and 3.0A at 5V, and they all stayed inside their limits. I didn’t try any chargers that supported higher amperage, because I was afraid that the L5 wouldn’t correctly negotiate to use lower amperage.
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I cannot explain this (not at this moment) but I think that overheating belongs to the higher voltage that some power supply initially sends out toward the Librem 5. Meaning if power supply rated (actually measured) as 5.20V I’m not using it as it will increase charging temperature “significantly”.
What is important to me to write now is that I’m looking for (expecting) to get and see that when the charged BPP-L503 battery reached its full capacity at 4.20V (red LED light off) connected power supply should show 5.00V. This means that when charging starts with the Librem 5 battery capacity under, for example, 40% voltage shown/displayed (as connected and current delivered) there, on tester/multimeter used, should be within range between 4.7V and 4.8V, steadily increasing in parallel as the battery capacity increases.
P.S. Might be it is only about my “taste” but I’ll continue to research in this voltage range only (by trying to exclusively use power supplies that do not output voltage higher than 5.00V, the ones that I decide to connect to the Librem 5, but most of them I do not even consider to connect as experimenting much is not my preference either). I already have a very reliable PD power supply for the Librem 5, therefore this post.
Interesting. Maybe higher voltage when doing current negotiation.
I saw several chargers that had a voltage of 5.20 when charging the L5, and I didn’t observe any overheating, but I wasn’t directly measuring the temperature of the charger and I relied on what the L5 reports as its temperature. My USB multimeter has a temperature function, but it is measuring the temperature of the wire between the charger and the L5.
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Yes, nobody should experiment with above 3.0A and even with the power supplies rated at 3.0A, while closely related to your post/intentions and in order to further decrease usually (as accustomed) measured charging temperature, simplest test would be to involve adequate cable+adapter (as shown in combo with the simple USB2.0 cable instead of …) where at least one (or both cable+adapter) contains 56kΩ pull-up resistor (not to involve here any extensive discussion about compliant USB-C to USB-C cables):
EDIT: For extended overview (ensuring/blocking to get output of 5.00V only), below picture shows small full protocol devices based around SW2305 controller (both of them). Sharing here while it is actually possessing very rare feature: its charging controller can recognize and work from provided 5V input and deliver output of 5.06V (without having any issues on transporting up to 3.0A, yet I do not recall that I tested ZC832 with my Librem 5):
EDIT II: Actually ZC832 (as above pictured power supply combo) charges well but the negotiated protocol isn’t my favorite (and therefore I’m not using it for this purpose, probably just because I cannot help myself in order to simply accept this shown negotiation protocol as some kind of advantage):
EDIT III: @amosbatto, as somehow “explained” above here is picture showing that charging current (amperage) can be decreased (relating to the same power supply in usage):
EDIT IV: Concluding here with my main reference numbers (when screen on, the way I like to see things when charging my Librem 5, as and when charging it for real, directly from my favorite power supply):
After few hours used PD power supply have gotten there (as mentioned above), reaching 5.00V (with Librem 5 turned off and battery calibrated full at 4.20V, it was just about right time to disconnect used charging cables):
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That’s complicated though because I thought the context that we were discussing is a convergence / dock scenario where it may be viable to turn off the Librem 5’s display. It is of course still generating the video signal for the attached display - and some users may want to have both displays on.
Yeah, like the Pi 4 has dual HDMI video outputs for starters - to go with 4 x USB ports (2 x USB 2.0, 2 x USB 3.0) and gigabit ethernet, more CPU grunt, plus all the pins - and only recommends 3 A.
Today I received the AENZR docking station from Quarnero.
I got excellent results. I tested it with 5 different power supplies and got 3 times 5V 2A negotiated and measured in all 3 cases above 1A consumption.
I get 5V 2A with:
- Power bank when using USB-A to USB-C. (when using USB-C to USB-C with the same power bank I get 5V 0,5A)
- With the power supply of Raspberry Pi 4.
- With a Samsung smartphone charger 5V 2A USB-A to USB-C.
I get 5V 0,5 A with:
- Sony smartphone charger 5V 3A 9V 2A 12V 1,5A.
- The original Librem 5 charger.
So we have a pattern here. The 2 newer and more high tech power supplies deliver worse performance than the good old USB-A to USB-C when having an USB-Hub/Docking station of this class in between the charger and Librem 5.
As a last test before clicking on the reply button, I decided to use the Librem 5 power supply with a small USB-C to USB-A adapter and USB-A to USB-C cable to the docking station. And wow 5V 2A. 
The idea behind is, that if you are on the go, you might not want to carry several different power supplies with you. This way a tiny adapter and a second cable are sufficient and you can go with the Librem 5 power supply.
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I need to admit that I was partially wrong as below AC power adapter to 5.2V/1.5A doesn’t overheat at all (when charging my Librem 5):
P.S. Also, no matter what amperage you see above, just trust me that it is 5.2V/1.5A power supply while it won’t boot Librem 5 without having its battery inserted (especially if USB-C to USB-C cable not as short as mine 
). And, I’ve already tested Canon PD power supply with my Librem 5 but do not want to overheat this post (although my Librem 5 in 
with it, and just don’t want that I share Canon PD power supply with any other device, as I actually did yesterday evening). As well, I’m mentioning Canon PD-E1 here while it doesn’t provide higher amperage to the Librem 5 than it actually requests (it is just pure joy watching them playing together).
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