Motor regeneration Circuit Issues
You need to swap the emitter and base of Q1 around (including base resistor), so that the Vrop across D1 is enough to enable Q2. Q1 MUST have a base voltage at least .65 volts lower than the emitter for it to work and drive the MOSFET.

The following circuit will dump current based on a voltage higher than D4 + 4 volts. At a lower voltage it has no effect.







simulate this circuit &ndash; Schematic created using CircuitLab