Please note that while the DHP group 31 is an excellent battery, when cycled deeply, it requires very high recharging currents to reach full energy density.
A hundred amp hour DHP/Odyssey group 31 wants a minimum of 40 amps applied until 14.7 volts is reached, 14.7 volts is then to be held for 4 hours as the current tapers.
Solar Cannot do this. 40 amps of solar is ~800 watts.
So after an outing, one needs to have a recharging source capable of 40 amps and holding 14.7 for 4 hours. It is unlikely you alternator will accomplish this task either, so you are likely not beginning an outing with the battery fully charged, and your solar cannot keep up with the load of the fridge, and the poor battery is getting nothing close to what it needs to return to full charge.
You can view the solar as negating your battery usage, if you have enough solar, but you cannot view it as a proper recharging source on an Amp hungry AGM battery like Odyssey which requires a high bulk charge current.
If these high bulk currents are not met occasionally, on a regularly cycled battery, the battery will not live a long life, nor perform as well as it otherwise would had it been recharged according to the manufacturer's regimen.
