HEI conversion help

You want the full 12V's, might not hurt to throw a charger on the car just to make sure its there. I bet it is and like you stated just from a low battery. Myself I would not add a relay. Like Trailbeast said, it could complicate it more.

Myself I bet your ok once you get that battery charged up. Let us know where your voltage is at after you do that.