As an added thought, with most of the HL tanks I own I had to make an opening in the back wall of the battery boxes too allow the new batteries to have a little more clearance. Most of the better batteries are going to be slightly longer than those that came with the tank and this is a mod that has been done by many of us over the years.
I;m not sure if there are any posts on how to do this but it is not difficult.
Just cut a window in the end of the battery compartment to allow the slightly longer packs to fit.