What's the typical voltage on a fully charged battery?

the max vlts is 14,if u run as one long battery.i think thats what you were saying ?if not it would be 4x14vlts...im doing the same thing but i put it in my truck

13.8 sounds like a voltage while being charged. What you might have to do is size the resistors going by the high voltage limit setting on your charge controller.
13.8 is a good charging voltage. If the battery voltage is this while at rest, not being charged, thats bad. When I say "at rest" I am saying that the battery is not being charged or discharged for at least 1 hour.
The range of voltages that a flooded cell deep cycle 12 nominal battery can go through on a photovoltaic charging system can be
from: 10.6
- this is the point where most 12 volt "gizmos" will not work. Even lights are so dim that they are practically usless.
to: 15.4
- this is an equalizing charge voltage and should only be used for short periods of time. Do not leave 12 volt nominal batteries and charge controller(s) unattended at these voltages.
Without knowing the full specifacations of your particular system there is really no way to narrow this down to a smaller range. One thing is for sure though, there is no one voltage, it will fluctuate.

Bone Scavenger, how old are the batteries and what temperatures are they subjected to? Sounds like they are in a remote location and may not be subject to discharge to fully recharge......