Many of the converters that come installed in RV's are quite bad. Magnatec and Wfco are known to be unreliable units, with the Magnatecs being called battery boilers as they only do a single stage voltage no matter what, and if left plugged in indefinitely, will overcharge and dry out a flooded battery.
The RV converter seems to think it's first task is providing 13.6 volts and secondary is battery charging. 13.6v will charge a battery, but it might not charge it fully, not if it needs an equalization charge, because of lots of cycling, when no grid power was available.
More modern RV converters like Progressive Dynamics, Iota, and Powermax have multiple stage charging, and various amp models. These can both power all DC appliances, when plugged in and can charge batteries with different voltage stages.
Regular Automatic battery chargers assume the battery is not hooked to any loads. If loads are hooked to an Automatic battery charger it will likely get confused and shut off, or perhaps undercharge, or even severely overcharge a battery.
And while these multi stage converters are much better than just a constant 13.6 output, they are not ideal for battery charging. The converter really has no idea how much power it puts out is going to the battery and how much is going to power DC loads like 12v lights ect so It cannot know when the battery is nearing full. It is playing pin the tail on the donkey.
An ideal battery charger would sense when the amperage required to hold Absorption voltages (14.2 to 12.8v) drops below a certain figure, and this figure is different for different batteries and changes as the batteries age.
There are no perfect battery chargers, everything is a compromise, and the human charging the batteries has the best chance of truly fully charging a battery, if one has the tools to measure and apply current until the battery is indeed full. Of course one also requires the interest and patience, as after all they are just batteries and just rented and work 'just fine' until they do not.
While undercharging obviously leaves the battery with less energy to release, undercharging also causes the battery to not be able to store as much energy as it could when it was new. The more cycles where the battery is not brought back upto full charge, the faster the actual total available battery capacity 'walks down', never to return. The battery can still be fully charged, but when new when it was a 100 AH battery, when it walked down in capacity it is now only a 85 AH capacity battery. If you still pull 50 AH, which was 50% on a 100 AH battery, you are now pulling this walked down capacity battery well below 50%, and increasing the rate at which it loses capacity. It is a slippery slope once it begins, and those with more available battery capacity are more resistant to quick degradation, however it is easy to have too much capacity for one's charging sources too, and cycled batteries need a minimum amount of charging current. Low and slow is oft touted as best, but not when the next discharge cycle begins that afternoon. A high enough rate that the batteries can be 95% or higher within 6 hours of initiating charging is wise.
A lead acid battery is like a Balloon whose outer skin gets hard and crusty when only partially inflated. The longer it stays deflated the more pressure one needs to apply to break the crusty skin on the balloon and allow it to expand. But it will never expand/inflate as much as it could when it was new, but the more often it is expanded as much as possible, the longer it can still be inflated.
The equalization charge is Akin to over expanding the balloon with extreme pressures hoping to return some flexibility to the skin.
When the skin is never stretched back to the original size, it cannot ever hope to return to that maximum inflation.
I just checked the BCI battery dimensions and it says the GC-2( 6v golf cart batteries) are indeed a slightly larger footprint than a group24 battery.
The standard group 24 is 10 1/4" x 6 13/16" x 9 inches tall
The GC-2 6v golf cart is 10 3/8" x 7 3/16" x 10 5/8 tall
These jar sizes are not all exactly the same. Some have protruding handles and can vary from the above. I've read on other forums that GC batteries in series drop in perfectly where paralleled group 24 batteries resided before but in some cases they would fight to share that same space.
GC batteries were designed around one purpose, maximum cycleability.
12v battery sizes were all originally designed around being put in an engine compartment and starting a car. When manufacturers decided to put deep cycle internals into these 12v jar sizes, the electrolyte/ lead ratios are much less than ideal, and as such, the 12v deep cycle battery, even the quality true deep cycle 12v batteries built by Crown, Trojan, USbattery, and EastPenn/Deka are all compromises, and can't endure hard cycling as well as the GC battery which was designed around cycling in the first place.
The Flooded Marine batteries are dual purpose batteries and are closer to starting battery than true deep cycle battery in internal construction.
GC batteries not only handle deeper discharges better, they are easier to fully recharge, requiring less time at absorption voltages and when equalizing, require less time to max out Specific gravity across all cells.
One deeply cycling 12v flooded batteries has their work cut out for them if they are trying to maximize cycle life. Making sure the charging system is adequate, is necessary, just for adequate longevity, and exceptional cycle life requires much more effort.
I do Not know if 6v GC AGM batteries have the same advantage as 6c GC flooded/wet batteries have over 12v flooded batteries.
