I might be able to help out on that one Griffin. Many times what happens is that the center posts get pushed down from getting screwed into the recharger to tightly. Take a paper clip or toothpick, hold the battery steady and insert the end just deep enough into the post center hole so you can apply a little leverage prying the center post up. The posts are pretty pliable, then repeat the procedure on the other side. It might just be that Carto is not making a clean connection. When this happens the battery lights up, but very little vapor is produced, causing one to feel like they are trying suck a marshmallow through a straw.
Let me know if this worked for you......If it does, just remember to screw the batts into the recharger just far enough for the recharge light to trip.