(05-28-2021, 09:02 AM)megous Wrote: dsimic: I've bought and checked with a better 5A cable. Now the voltage at the Type-C connector is 4.9V at max load, so the max PBP can draw from DC/Type-C VBUS is 11.34W (that's what I measured).

So that's the same as your theoretical 11.4W limit.

• The target battery voltage is configured using a couple of resistors on the PCB, so those would need to be replaced.
  
• Reducing the target battery voltage and leaving the maximum battery charging current unchanged would result in further reduction of the maximum power that can be taken from any of the two power inputs, and the battery would even more often be used as the power source for the laptop, even if it's connected to a charger.
  
• The above-described issue could be mitigated by increasing the maximum battery charging current at the same time, but unfortunately there isn't a lot of room for that.  However, there might be a sweet spot.
  

(06-11-2021, 10:34 AM)dsimic Wrote: The good news is that it should be possible to tweak the desired maximum battery charge level by adjusting the BQ24171's target battery voltage, which is described on page 16 of the BQ24171 datasheet.  However, there are some bad news:

• The target battery voltage is configured using a couple of resistors on the PCB, so those would need to be replaced.
  
• Reducing the target battery voltage and leaving the maximum battery charging current unchanged would result in further reduction of the maximum power that can be taken from any of the two power inputs, and the battery would even more often be used as the power source for the laptop, even if it's connected to a charger.
  
• The above-described issue could be mitigated by increasing the maximum battery charging current at the same time, but unfortunately there isn't a lot of room for that.  However, there might be a sweet spot.
  

By the way, after further analysis of the way BQ24171 is used in the PineBook Pro, I'm pretty sure that increasing the maximum battery charging current is the only doable way for increasing the maximum power draw from any of the two power inputs.  All components in the power path should be able to handle a 15% to 20% increase of the maximum battery charging current; combined with additional cooling applied to the BQ24171, this should be a win-win hardware modification.

Of course, I still need to re-evaluate the entire approach a few more times, so we definitely stay on the safe side with such a modification.

(11-20-2020, 11:51 AM)xyzzy Wrote: Anyway, a new PCB rev that will draw more than 3A from the DC barrel connector isn't really viable, since it wouldn't be possible to connect any of the existing power adapters without overloading them.  It's not possible to just just "draw less" from the 3A adapter.  The charger will try to draw more and the adapter will be unable to keep at 5V and drop voltage, or totally lose regulation, or trip a thermal fuse, or (I see the pine supplied adapter is not UL-listed!) catch fire.

(12-04-2020, 11:10 AM)dsimic Wrote: Once the CPU cores are all kept at 100% utilization for an extended period of time (20+ minutes), the heat soak from the SoC affects the battery charging IC (i.e., TI BQ24171), which goes into thermal shutdown.  As a result, battery becomes rapidly discharged because the loaded SoC uses a lot of power and there's atually no charging at the same time.  Turning the laptop upside-down and providing additional coolling to the back of the laptop turns the previously mentioned 20 minutes into about an hour, but the BQ24171's inevitable thermal shutdown happens anyway.