What is the actual possible voltage range ?
I would like to run the Radxa ROCK 5T directly of LiFePO4 cells which deliver 10V ~ 14.5V.
Would the internal voltage regulator able to handle that ?
The primary buck IC according to the schematics seems to be
The chip can handle up to 26V and 10V should also be sufficient to generate to necessary 5V. But the recommended values for some components, in particular the inductor, change with the input voltage. The capacitors should be good until at least 16V (next lower common value would be 10V). So my guess would be, that you will not kill your 5T when running it on 14.5V. But please double check the schematics before trying. I might have overlooked some details.
In case anyone else is looking for this information, I have confirmation from Radxa tech support that the input voltage range for the DC power connector is 5-20V.