Just installed two 6 volt batteries in the shower sump. Thought you might be interested. Attached are a series of pictures of the installation. 1st, Battery boxes fitted into the sump. 2ed, holding framework to secure the batteries and provide a base for another battery platform. 3rd, starter battery secured on the original sump/battery base. 4th, added a 1 extension to the engine housing to allow for group 27 batteries to be stored. In the future the battery bank may be expanded to four 6 volt batteries. They are not needed at this time.