What's likely happening is that the charger is pumping out all the amps it can until its "absorption" timer expires and puts it in float mode. Unfortunately, that isn't long enough to fully charge your 675 amp hour bank of T105s. The rule
of thumb is that you need a charger capable of putting out 25% of the capacity of your bank in amp hours, or about 169 amps. It needn't be that high, 100 amps would do, but 25 is way too little.
More advanced (read programmable) battery
chargers either allow you to set the length of the absorption phase or the capacity of the battery bank (so that it knows to switch to float mode when the charge rate drops to 5% of capacity).
Anywho, Newmar makes good reliable stuff, but their battery chargers tend to be pretty basic. I recommend Magnum inverter/chargers. Still made in the USA.