The boost converter is the right idea. You might be able to find a more powerful one or use two in parallel (not sure this is possible). 5A is pretty good though.
28.0 to 28.2V sounds good. The batteries will be pretty charged by that voltage. You could run at that voltage for fairly long periods without gassing the cells. Most lead bricks will have it printed right on the battery.
28.0 to 28.2V sounds good. The batteries will be pretty charged by that voltage. You could run at that voltage for fairly long periods without gassing the cells. Most lead bricks will have it printed right on the battery.