Battery Replacement 24 vs 27 AGM

ReenieG

I have a 2018 320S that was purchased used with a plastic tub. It came with a group 24 Interstate battery. I'm not having much luck with these batteries. I'm on my second battery and although it's less than a year old, once again, this one is not cooperating. I know, I know... yes, there are all sorts of reasons, but my question is this...

I was reading on this discussion about several T@Bbers with older T@Bs than mine and they're talking about replacing with a group 27 AGM battery and it seems that's what they currently have. Is this possible for me? It didn't seem like I had enough room to increase the battery size in the battery box and with the frame within the tub. Maybe I do? Anyone? TIA

dragonsdofly

@ReenieG, most group 27 batteries will fit in your tub with a battery box. You may have to slightly angle or change the box position, but it is possible. I have a 2017 with the plastic front tub and I have a group 31 battery in the tub. Due to it's larger size (than a 24 or 27) it is angled in the tub and does not have a battery box. We had to place a piece of plywood in the tub bottom (anchored) to secure the battery onto. We used a plastic battery box lid on top and strapped it down, so that too is doable. 2 6V gc (golf cart) batteries can be arranged to fit also without too much refitting. You have options.

If you change to a group 27 battery, you will need a battery box to fit a group 27.
 -Denise

ReenieG

@dragonsdofly This was what I was looking for... a good solid EASY solution for more battery amperage. Thank you! Do you have a pic you can share? It doesn't seem feasible looking at my tub since I currently only have a group 24 battery box.

MuttonChops

@ReenieG As @dragonsdofly noted a Group27 will fit in the tub but not in the standard Goup24 box.

I installed a Group27 and it was easy (sorry, don't have any pictures).

What I did was place a piece of plywood in the metal frame [under the plastic Group24 box] to provide a level, strong base to mount a new Group27 box. It has worked well for me.

Grumpy_G

Looks like the frame is different from the older T@bs but you might be able to adapt something similar: https://tab-rv.vanillacommunity.com/discussion/14952/battery-tray-enlargement

YanniLazarus

I used pressure treated wood to build a flat base inside the battery box frame. There is no need to keep an AGM battery inside a box. This allows you to angle and install your AGM battery oriented however you want on top of the wood base- and hold it in place with several cargo straps. I choose to stack 2 6V golf cart batteries, but my guess is that this will work for your larger 12V battery as well. My T@B 320S is a 2020.

SLJ

I put a 100AH AGM inside under the bench by the door. No battery in the tub now. (2021 320S)

Sharon_is_SAM

@ReenieG - are you going to place a 100 Ahr battery?  Are you mostly camping with hook ups?  Are you using solar?

ScottG

I made a similar mod in 2016--see pics and description here. It's a group 27 box but it's large enough to fit an Interstate group 31. 

rcuomo

Just an FYI- 320S generally came with an Interstate HD24-DP dual purpose 64Ah battery weighing 41.2#. No need for dual purpose battery in non starter use. I’ve replaced my tub battery with an Interstate SRM-27 deep cycle battery. 88Ah @ 50.3#. And under the left side bed, a Renogy 100Ah LiFePO4 to run my 1500 inverter. Solar hook ups for both. 

Maple_Geek

Have you considered a Lithium 100Ah group 24 battery? I understand they are much more expensive than AGMs but they are also much lighter and will provide much more capacity. Just a thought...

tombeaux

We put a group 27 size AGM in our 2017 320S. Using the YanniLazarus photo above, note where I have a yellow circle. The larger battery box fits the width of that bracket, but not the length. I used an angle saw and took out the part of the angle iron that sticks up so that the longer box would fit in that space. Then I could squeeze the group 27 box in (barely). The Camco brand group 27 box did need some trimming on the lid to fit inside. The second photo notes where I trimmed the lid. Our original group 24 that came with the T@B lasted more than two years and we are heavy users. We did have some instances where we probably drew it down to the point that we damaged it some. We keep it charged with a Renogy suitcase solar system when boondocking and haven't had any issues with the AGM for the past two years. This is the battery we bought - https://www.amazon.com/gp/product/B00S1RT58C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1