Connect VS(A) -ve and VS(B) -ve at batt -ve, and connect VS(A) +ve and VS(B) +ve at batt +ve. This is parallel connection. Theoritically, better noise filtering, voltage stabilizing and reserve more current for instantaneous load. But practically, many forumers commented that too high capacitance caused their cars to be sluggish. If you really want to put in 2 VS, try to connect them to your batt one at a time to prevent high inrush current surge.