We haven't finished calibrating our bridge yet, but we've come up with this to help with the calibration:
With (2) 14.2 lb 6.58" deep (round to 6.6) batteries, the bridge won't tip at 28" from edge to centerline of the bridge, but it will at 30", per field tour video #5. So, that says the torque from the bridge weight is greater than the torque from the battery weight at 28", but less than when at 30". The bridge weight is 3" to one side of the hinge while the battery weight is the distance minus 3" plus half the length of the battery (3.3"), so the center of the battery is 0.3" further from the hinge than the battery edge is from the centerline of the bridge.
Given that, our chart is attached. If you know where your batteries cause the bridge to tip, you should be able to look up (or interpolate) your current deck weight and adjust it to get to the 28"-30" range.
Unless, of course, I messed this up again ...
