mucking about with resistor values:
Code:
tap divider sense watts resolution per bit
12v 20k/10k 4v 0.005 0.01171875v
24v 50k/10k 4v 0.010 0.0234375v
36v 80k/10k 4v 0.015 0.03515625v
48v 110k/10k 4v 0.020 0.046875v
60v 140k/10k 4v 0.025 0.05859375v
72v 170k/10k 4v 0.030 0.0703125v
max bit level rounding error @ 72v = +-0.123046875v