Going from 45 to 80 you may, as Rusty said, need a wire upgrade
Also, you need at least 200 amp hours, I mean at least 200, 250 amp hours would be better, of batteries to use that 9280..
Battery capacity times 0.3 for most batteries, (Less for gel, more for Lifeline AGM's)
so you should have at least 250 amp hours unless they are lifelines, and I'd want at least 200 amp hours if Lifeline.
NOTE: if your system, like mine, also charges the chassis battery,, Do not forget to include it in your amp hours.. I have a 9180 with wizard (Effectively the same as the 9280) and only a pair of U-2200's That's 230 amp hours or there about,, NOT counting the chassis battery (About another 80 or so) so I"m good. Very good.. I need to water those U-2200's... about every 12-14 months
Home is where I park it!