Is there a way to power the mainboard from 20V directly? I’m going to build a 100 Wh battery for the Framework 13 and would rather not use a dedicated board that converts to USB C PD like this one.
Hi this has been discussed I’ll see if I can find it did you search and what did you find?
Why a 20V maybe a 16V i.e. 4 x 4.2V not 5 x 4.2V Li-ion
I think RootInit was aiming to build a battery that’d work as a drop in replacement, using the same battery connector, with the mainboard charging the battery and communicating over SMBus, which could be quite difficult to get working. I tried putting 16.8V on the battery connector directly but the EC probably assumed it’s a faulty battery so didn’t let the mainboard boot.
It’d be a lot easier to build a custom battery with it’s own charging circuit and power the mainboard over USB-C as a power supply than convince the EC that it’s a valid battery, but bypassing the USB-C stage would be even better. I suspect there’s a point on the mainboard where the 20V can be directly applied to power it without having to go through a USB-C connector - if only I had the schematics…
The battery would be four lithium cells in series and use a boost converter to get to 20V. I wouldn’t go for five cells in series since I’d need both a buck and boost converter as the full charge voltage is 21V.
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The expansion bay has pins ready for an extra battery in future, you could maybe at a 20V jack to an expansion bay and feed some power into the device over the battery pins.