I have just installed an ABR Sidewindwer dual battery monitor on my GU Patrol. Had to modify it to suit my Redarc battery isolator. Seems to work in spite of me attacking it with a drill and soldering iron. All this voids the warranty, but what the heck. The monitor is a bit sensitive to viewing angle, so I had to tilt it up so the driver can see the voltage readout. Mounted the device on the pop-out panel between the car radio and the steering column.