Cooked Battery

I have a 2016 RPod 180 with a Interstate (Canatron) Size 27 12 Volt acid battery.  I must admit the first year I never really paid much attention to it but we only went out camping about 4 weekends, (we mostly boondock).  This battery actually came with a RPod 171 but we traded it in for a 2016 1/2 RPod 180 and just kept the battery as it was bigger than the stock 24 size battery from the dealer.

This year been out about 30 days so far and had no problems with the battery until now.  We just got back from a 4 day dry camp, so first thing I did was hook up the 30 amp cord (also needed 12 more feet of 12 gauge extension cord to reach the 15 AMP outlet on the side of the house) to get the battery charged back up.  I had read that the RPod 180 has a good 3 stage charging system and I was going to try it out by leaving the battery charging via the onboard charger/inverter in the trailer and monitor the voltage.  I had hooked up to 110 AC for 1 week and never had any problems with battery cooking.

We have in the past month, been out twice on four day weekends, drained the battery down to 11.6 Volts both times and I know that "they" say it is best not to go below 12 volts or 50%.  

Anyways, I'll get to the point, after 12 hours I noticed a smell and saw water on the pavement under the battery.  It was steaming pretty good and I could hear it boiling.  I quickly disconnected the cord and switched off the battery (I installed a battery switch on the battery box to the neg battery terminal about 4 months ago).  

It was really hot, I suspect that if I had not noticed it and went to bed I would not have a trailer in the morning!  After it cooled down some I checked the fluid levels  and they were not too bad, I did top them up with distilled water.  After reading some about "cooked battery", I realize this was a mistake, as the battery started to get warm again from the chemical reaction with the acid and distilled water.  I should have waited longer before adding more water.

I know the battery is likely toast, but why did the charger in the RPod keep charging?  I thought the 3 stage charger would give a bulk charge then go to the absorption, then finally a float.  Before this all happened, I did keep checking the readout of the battery on a 12 volt LED I had installed and saw it was charging at 13.6 Volts and when my battery started to cook, it was still at 13.6 Volts. 

Even though the Interstate 12 Volt 27 size battery is 2 years old, the 2016 RPod 180 is new from a dealer but we just bought it in April 2017.  So everything is still under warranty.  There is no serial number, or any info on the battery.  Interstate web site shows it is a deep cycle battery, but not even the label says that. 

How do I determine if the 180's charger is the problem or if the battery is just bad?

I checked the battery at it's terminals about 2 hours later, and got a direct reading of 12.6 volts.

My dealer that I just bought from no longer carries RPods and they are 1.5 hours away.  Hope to buy two 6 volt Golf Cart batteries and a 100Watt Solar panel but don't want to risk wrecking new expensive batteries until I find out if my RPod's charger is ok.  

Any help would be appreciated.  

Thanks

Bob