I am considering fitting a BM1 to my boat. The boat has a single battery which of course is used for both starting and domestic purposes. The main domestic draw is a Waeco CF18 portable fridge. I have looked at the NASA site and studied the manual which states it can not monitor the starting battery. However , it seems to say it is not required rather than saying the unit technically can not monitor a starting battery. I will contact NASA and see what they say but would like to ask if any formumites have fitted a BM1 to a singel battery system and if so did you get good data from it ?