I just finished a long and extensive search for the best battery for my travel trailer.
I located the best at Amazon....to make a long story short here is my final selection...best type: AGM 12 volt true deep cycle WARNING: Do Not Buy any battery marked RV/ Marine deep cycle...these are not real deep cycle batteries.
Final selection with best type and price that should last a long time in RV application......source...Amazon....delivered to your door...cost $149.99 plus $10 shipping.
All AGM batteries require no maintenance...they are sealed units...cannot leak acid....never need additional fluid...not your grandfather's battery...acid is absorbed in fiberglass Matts between the very thick and heavy plates (RV/Marine deep cycle style batteries have thin plates and liquid acid that can leak...they are designed to start engines and show "CCA rating" for starting power.)..they are not designed for constant charge/discharge cycles like a Travel trailer's battery. AGM batteries are designed for deep cycle use not starting power.
From Universal Power ...AGM...sealed true deep cycle 12 volt...100AH..battery. This is a group 27 sized battery with the Amp Hours (AH) you need for boondocking
Just search "AGM Deep Cycle batteries...12 volt". On Amazon to locate this unit.
The reviews for this product are all excellent. Many sold for use in solar
RV buyers report many years of excellent service from this AGM (stands for Asorbed Glass Matt type which has the longest life use cycle of the deep cycle type batteries @ 5-10 years) group 27 (size) 12 volt battery.
Mine arrived on time (typical for Amazon). It arrived fully charged to 12.8 volts on my digital volt meter. It was well packaged in a double carton with protective padding. Note: this is the only acid battery that can be shipped via FedEx or UPS because it is a sealed unit. It also comes with all connectors you will need to put it into service.....and....YES!! I would order it again....it is the most cost effective deep cycle RV battery you can buy in the AGM group....why deal with liquid acid batteries when the new AGM sealed batteries are far superior??
Amazon: Universal Power Group 45978 100AH AGM sealed lead acid battery.
Group 27 size (12" long X 6 1/2" wide X 9 1/4" high). UB121000.
Amazon lists this battery several times for both solar power
use and RV use but all listings carry the "UB121000" identifier...all list price as &149.95 +$10 shipping...and are the same battery.
Good luck and Happy Camping.