Examples of contactor controllers, systems and methods enable quick-turn-off (QTO) using an output voltage of a contactor controller when its supply voltage is below a threshold but does not interfere with QTO when sufficient supply voltage is available. In an example, when VM loss occurs, a high-side (HS) clamp of a contactor controller is disabled, and a low-side (LS) clamp current is generated using the output voltage. The LS clamp current may be adjusted to achieve a desired QTO voltage. In another example, a HS clamp is disabled and the charging of the gate of a LS field-effect transistor (FET) is enabled only when the output voltage increases above a power-off QTO threshold (less than the LS clamp voltage); the QTO voltage is set by a voltage detection and comparison circuit of the contactor controller.