So this product is still in development. Hence the hardware is ready for regeneration, but right now the firmware doesn't support it yet.

In principle it works by just putting a high charge current capable battery on the DC bus, and simply dumping the regeneration current onto the bus, and the battery will eat it, as the bus voltage rises.

The "Architecture" heading, a bit down on this page explains more: https://hackaday.io/project/11583-odrive-high-performance-mo...