MT034 Lay-Up and Survey Battery Isolator — 150A, ON-OFFLay-up season and pre-season survey are when battery isolation actually gets examined. A surveyor wants to see that the master switch isolates everything downstream, that it is rated for the circuit, and that the terminals are sound. Owners want a switch that still turns freely after a winter in a cold locker.MT034 is a 150 amp, two-position rotary isolator for 12 to 24 volt DC systems, sized for the typical cruiser,