So do you want the dc max output to be the same or less then the dc max input
max out should be more than max in if you're adding fuel.
ie: you're running 7800 hi, your setting is +22, then if dc in is, say 68, then dc out is 90.
The problem will come in when dc in & the added fuel get to 99, then adding fuel on the box will no longer do anything.