I just got two new batteries for my demo, and one fully charged and one didn't. I ran them the next day, and they both went to full charge after re charging. Your new batteries just needed to be cycled like I said before. New batteries often do that from setting on the shelf for a long period of time, or from never being fully charged in the first place.
It seems to me that overall I get longer battery life charging with a 5 amp per bank rather than a 10. Both work well. The key is to re charge them ASAP after use, and keep them charged either by trickle charger or checking on them.
We only sell the Best. Ranger, Xpress, Yamaha, Suzuki, Tohatsu.