I am impressed with my group27 Northstar, but it requires the occasional high amp recharge, after about 4 to 5 deep cycles, and 100% as often as possible.
From 100% to 50% and about 350Deep cycles and many hundred more shallow cycles, the voltage it maintains under load for AH removed is nearly as good as when new.
Northstar specs 14.46v absorption voltage at 77f
use thick cables from the PD and it's 14.4v should be good enough.
Exide batteries are not regarded well, from What i read online.
Been a long time since I owned one.