Interesting pieces of equipment. For the type of boating my family and i do, i don't see these pieces of equipment being that useful since we already have a dual battery system with isolated banks so killing both batteries would be very difficult under normal use.
Our batteries are both deep cycle with one being a deep cycle starting and are connected via a
West marine BatteryLink ACR so that the batteries are connected during charging and when the boat is shut off, the batteries are isloated. We have this
switch panel to separate the wiring in the boat into two primary circuits, house and starting. All of our stereo and accesory items are wired to the house switch while the primary engine circuits and nav lights, basically everything you need to operate the boat, are wired to the starting circuit. If we are moored in a cove and leave the stereo running all day and completely kill the house battery, it doesn't matter because the starting battery wasn't used all day so the engine will fire up and the accesory battery will charge on the way back home. If for some reason the starting battery died, say the blower was left on, then just flip the emergency connect switch and the house battery will start up the engine.
The chances of killing both batteries during a trip is very unlikely. That's why i don't see the need for those devices. If you have a larger house circuit and more electrical items on board that say have to run a lot, say a fridge, then i can understand the need for such a device. For our boat, not really necessary.
Just my $.02
Battery Monitoring
