Bypassing the Battery with an AC/DC Power Supply

So with the advent of an AMD Phoenix APU mainboard, and its powerful graphics, I had an idea to try building a small HTPC using a Ryzen mainboard when they become available. However, I don’t want to waste a precious USB-C port on power delivery, and would rather an internal PSU over an external one in general due to a general dislike of power bricks for small, stationary devices.

Has anyone messed around with this? Looking at the pin-outs and voltage diagrams on GitHub, I cannot tell if this is trivial (just hook +17.6V in to pins 1-3, and ground to pins 8-10, using 24 AWG wire), or would basically require me to basically emulate the BMS (which I am thoroughly interested in), or anything inbetween.

Worst comes to worst, I could always try engineering a custom internal USB-C hub that has 100W power delivery and draws its own power from a simple DC input… but I’d rather not do that if at all possible, since any kind of custom PCB project tends to balloon in cost real fast in my experience.

As someone attempting something similar (probably over the summer when I have more time)–were you able to make more progress?

I am trying to frameworkify a thinkpad, and I’m thinking that I might be able to mod the external battery into a USB-C power delivery module so I’d have, basically, the internal battery (just ordered one) and that to power the machine. I’d love to just wire up 2x native batteries, though… which is why I’m going to take the one I ordered apart to see what I’m working with and find out if my plan would be possible.

You could probably also mod the embedded controller firmware to accept your dc power but I really don’t see much advantage over just using a usb-c psu.

That sound very interesting. Which model Thinkpad? Will you be trying to use the Thinkpad screen?

@MJ1 I’m currently working on a T25 (anniversary 7-row). I also bought a really clean T510 in case I just want to say screw it and build a giant tank. :slight_smile:

All of the details are up in the air at this point–I’m still in the parts-gathering / reading phase. My used framework intel mobo just came in the mail yesterday. I hope to get this done during the summer in prep for the AMD board in the Fall.

Oh a T25, very nice. Is the pinout available for it’s keyboard? I know there are schematics floating around for a bunch of Thinkpads, I don’t know if that includes the T25.

@MJ1 I have schematics for the T470 and some other machines… I’m working on adapting it to USB. Slowly but surely, I’ll get there. I hope!