I would really like a USBC module that only allows power in one direction. This would help when using power banks to charge the laptop or to charge a power bank from the laptop. I would have one innie and one outie. Of course a switchable one would also be nice.
It is annoying to plug a power bank in to charge the laptop and find out that at some time the power bank ran out and the laptop started charging the power bank. Back and forth they go until everyone is dead.
Could be the problem with your power bank. it should never request power from the laptop
Unfortunately, this seems to be a problem inherent to USB-C PD when two devices are connected together who are Dual-Role Power devices and who have the same source/sink preference. The USB spec says it shall be decided randomly which device provides charge. Certainly way less intelligent handling than expected. Feature Request Megathread - Expansion Card - #173 by MJ1
So you just have to check which way power is going, and if it’s not the direction you want, try again. 
This is something that needs to start being solved within powerbanks.
3 Likes
I agree the powerbank with dedicated usbc in and out ports, or a switchable port would be great, but they are not going in that direction. Framework could take the lead as a feature. I would buy a one way USBC module the moment it comes out. This would solve a real problem.
1 Like
you might not have tried a 100w 100wh powerbank with one USBC In/Out port. Wall adapters are out only and will charge the bank up and stop when full. Most phones, flashlights, and such will only accept charge and will be charged by the power bank and stop when full. Some computers with dedicated barrel jacks can tell when they are on AC power and will only charge the power bank. But the framework is charged by USB, and cannot tell if that USB power is coming from a power bank or an AC adapter, and the framework usb port will gladly suppy 100W to anything that requests it.
I’m not sure it’s willing to provide 100W out:
If there was better PD firmware. There is no real reason why you should not be able to force a particular port as being sink only, instead of dual.
Here is my vote to make that firmware opens source so we can fix it ourselves.
Also, the linux kernel does not understand EPR charging mode, which is why it reports 5V 3A even when charging at 36V.
My mistake.
In my experience this is not a problem with just framework, this is an issue with many laptops and devices. USBC has functionality issues when charging one battery with another battery, it cannot decide which direction to send power. If it was just the case that you could replug until you randomly got the correct direction, that would be a minor inconvenience. But the nearly universal case, in my experience, where at the end of the charge cycle the direction reverses rather than just stopping, that makes it nearly unusable.
My hope is that framework could lead to a fix, in the same way they have fixed repairability and upgradeability. And that by example, drag the rest of the industry along. I truly enjoy my framework 16, and am an evangelist for the brand and how it solves problems for people like me that are cursed with the overwhelming desire to fix things ourselves.
I have an external battery pack.
It has two USB sockets.
One for “charge in” and one for “charge out”.
I have to move the cable depending on which direction I wish the charge to go, but at least it is workable.
The problem charging case with USB-C is when both ends have “dual mode” capabilities.
“dual mode” being they both sink and source power.
If the firmware supported it, one could let the user decide.
I.e. if both ends are dual-mode, we prefer to act as a “sink”, but also user configurable to prefer “source”.
Perhaps the way to fix that is to see which side can supply more power, and make that side the source. In the case of a framework which can supply 15W max then if the battery pack can supply more than that then it becomes the source.
1 Like