A multi-charge ignition system including a spark plug control unit adapted to control at least two coil stages so as to successively energise and de-energise said coil stage(s) to provide a current to a spark plug, said two stages comprising a first transformer (T1) including a first primary winding (L1) inductively coupled to a first secondary winding (L2); a second transformer (T2) including a second primary winding (L3) inductively coupled to a second secondary winding (L4); characterised in including first switch means M1 electrically connected between a voltage supply high side and the high side of the first primary winding, a second switch Q1 electrically connected between the first primary winding and the power supply low side supply/earth, a third switch connected between the junction of the first switch and high side end of the first inductor and a point between the low side of the second primary winding and low side supply/earth, and further including a fourth switch located between the low side of the second primary winding and said point, and a fifth switch located between said point and low side supply/earth.