The mo.lock backup capacitor is used to level short-term voltage drops to the main relay.

If cranking the engine via the electrical starter is slow and resistive, very large single cylinder capacities or high compressions can cause significant voltage drops. Implementing a backup capacitor prevents short-term voltage drops from de-energizing the main relay.

Excessive voltage drops can only be prevented by an optimal, sufficiently powerful battery and the lowest possible resistance in the vehicles electrical cables.