I had a Group 27 Interstate in my 2016 Casita
.. It didn't seem to last 4 years, and I know previous owner and myself always had the Casita
plugged in. (I think it was bad when I got the trailer 18 months ago).
I researched, and couldn't find if group 31 would fit, although I've read somewhere Casita
now ships new units with group 31.
Group 31 is same width Group 27 but a little taller, and a little longer, and most importantly 50%+ more capacity (135ah vs 88ah in interstate G27)
Anyway, I wanted to confirm if anybody is searching that this model fits.
I had to create a new aluminum bracket to make sure battery
doesn't shift sideways, which I created out of a 1/6" x 3/4" aluminum angle iron.. Slightly bigger (1") may fit, but original wouldn't (door would not lock, and if you cut it down, it may still be too thick and you won't be able to reuse the bolt).
I then drilled a hole closest to the edge in the middle, flipped the bolt as there was only enough space on bottom for a wing nut and looks like a factory install (see pic).
VMAX says these will last up to 10 years or 900-3500 cycles if you don't discharge more than 50%, plus offeres half the discharge rate of other AGM batteries (1-2% per mo).. that's a 10% discharge tops over winter. https://www.vmaxtanks.com/FAQ_ep_42.html
I saw other campers use these and recommend.
Will the on board Casita charger suffice?
Q: What kind of charger is best for my VMAXTANK?
A: A 14.5V Constant Voltage Three Stage AGM battery charger must be used to charge VMAXT batteries. These chargers - AKA: Smart, Automatic, Microprocessor Controlled, IEI- have three charging stages that changes as the VMAX charge increases. It switches from Bulk to Acceptance to Float. Please Click on "Description" tab of any battery to get charger ratings for that battery.