Why two power ports on a budget laptop??

[dsimic]

Did you try to run the CPU and GPU at full tilt and charge an empty battery while using a 90 W charger disguised as a 170 W unit?  I'm pretty sure that wouldn't work well.

I forgot the exact way the ThinkPad chargers identify themselves to ThinkPads, so this was a good reminder.  Here's detailed information, if anyone wishes to check it out.  However, sensing a resistor is also a way of communication between the charger and laptop; sure, not nearly as complicated as the communication required for establishing high-power USB charging, for example.

Haven't tried that specifically on W510 with 90W PSU - unless I load the GPU it just doesn't breach the PSU limit. But, as I already said, I have tried that on the much older R50 that AFAIK doesn't have that resistor and third pin in PSU for wattage sensing, and the result was that it works, but the battery discharges, though slower than without any PSU. I'm not an electrical engineer, but my understanding is if more current is drawn than PSU can supply without voltage dropping below certain limit then battery will be discharging instead of charging, providing the extra current needed for the machine to keep operating. If this is a misconception on my part I would love to see someone correct it. Until someone does - I'm pretty sure there is more to it than simply overestimating the power consumption. R50 on 30W PSU without battery - definitely unstable, unable to reach full performance. But plug the battery in and it chugs along just fine, with battery discharge rate that appears to be several times slower than running on battery alone.

The sad thing about PBP is that the internal charging circuitry isn't maxed out at around 3 A.  It can go up to 4 A, but it is simply limited to 3 A through the configuration of the BQ24171 charger IC.  By the way, guess what, the charger IC is configured using resistors.

Yes, yes, yes, I read the thread about it, no need to be so pedantic :-) Whatever are the details of the cause, the bottom line - overall power input to the machine is limited by the current battery can use to charge and the machine will not run without battery (the switch on the mobo aside). The whole power system in PBP is (artificially, though probably unintentionally) bottlenecked on the battery charge current, whereas on the same ThinkPads the bottleneck is the PSU itself - if it is not powerful enough the battery will not charge at full speed and may even discharge to supplement PSU, and if PSU has excess power the battery will not charge faster than is safe. But one more observation - it seems to me that unlike the already mentioned R50 on PBP the battery is either charging (however slowly), or just discharging with charger making no difference whether it is connected or not - while I couldn't get any meaningful data from powertop the time measurements on similar loads show little difference between run times with no AC connected and AC connected with red light next to charger port blinking. If this is also a misconception - again, by all means please correct me.

My apologies for the delayed response.

You're right on both of the points above.  If the battery charging current (or the max. current available from the charger) is greater than the current required by the computer, the battery may be charged.  Otherwise, the battery will be drained to compensate the difference.  The underrating of the charger outputs and overestimation of the system power consumption is what actually makes such "charger overclocking" physically possible.

As another example, while debugging some issues with the PinePhone, I've seen a 5 V, 1 A "plain" USB charger supplying 1.2 A happily for extended periods of time.  That's another example of the "charger overclcking".

The trouble with the PineBook Pro is that the battery charger IC is configured to think that the computer needs no power to operate, so the entire input power from the charger is capped at the max. battery charging power, while it could go higher.  All of that goes back to the above-described behavior.

However, I've switched from the factory-installed Debian to Manjaro ARM on my PineBook Pro, and it seems that one of the charging issues was caused by some weirdness inside the Debian's Rockchip-provided Linux kernel, which caused much higher power consumption.  The laptop is actually now able to stay away from discharging the battery while being subjected to pretty much the same load as it was the case with the factory-installed Debian, which used to cause the battery to become completely drained in a few hours, despite the laptop being connected to the 5 V, 3 A charger.

I'll provide more details about Manjaro in my another thread.

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I think more obvious answers could be;
* They thought 5v @3amp would be enough
* Pinebook Pro is their first USB-C charging device, so they wanted a backup plan for power in case it did not work well, (or at all), see above.

Unfortunately, the PBP's Type-C charging option doesn't seem to have been directed toward a backup plan.  According to the PBP circuitry, the maximum current allowed to be taken from the Type-C port is even lower than the maximum current allowed to be taken from the barrel connector.  More precisely, it's 2.52 A vs. 2.98 A, both at 5 V of course.

Sorry, I meant that the barrel type jack was the backup plan to the USB-C charging.

As for the amperage limitation, I don't know. Could have been a mistake, (though unlikely).

One thing I have not yet read in this thread, (could have missed it), is that over-clocking the RK3399 SoC's CPUs, (and potentially the GPUs), is now "standard" for our Pinebook Pros. Remember, this SoC is not intended as a high performance device when compared to x64 laptop CPUs. But, a majority of people wanted their Pinebook Pros to be faster. (The Pinebook Pro IS already faster without over-clocking than the original Pinebook laptops.) So they accept the excess heat, power draw, reduced battery cycle, etc...

There are people requesting an even faster, (and potentially a more power hungry), SoC for either an upgrade. Or next version. (Some want a 15.5" or 17" screen too, or more internal peripherals like a 2.5" SATA disk bay... which would also take more power.)

I do agree that something can be improved with the power charging & delivery systems.
On the other hand, I think the Pinebook Pro is suitable as is for many tasks. Perhaps not as a daily laptop for people who need more power.

My apologies for the delayed response.

Please, don't get me wrong, I'm perfectly fine with the performance bracket that the PineBook Pro belongs to.  I do not expect wonders, and I would never try to overclock it.

However, I expect the laptop not to discharge its battery down to 0% and turn itself off while being connected to the factory-supplied charger.  Such behavior is simply not acceptable; however, that's exactly what I've experienced with some light usage, i.e., low CPU load, WiFi off, etc.