Whats normal voltage drop from a 4amp load? (210ah)

I think the battery tender goes to 14.3 or 14.4v while my flooded batteries want 14.8?

Pretty sure the battery tender is 5amp. Im using it as a temporary charger to cycle the batteries in the garage once a week. Bought the new batteries for a camping trip back in Feb and didnt need them. Should have waited as im plugged in most the time.