To avoid misinterpretation, I'll mention up front that the following is discussing LiFePO4 (lithium) batteries and, as several have mentioned, is very different than recommended care for AGM lead acid. And I'm also basing it on the research I've read. Very interested in hearing about any research/papers that have counterpoints to any of the below.
It seems its best to store LiFeP04 between 40% to 60% SOC; not at 100% SOC. Turning off the main load breaker should keep all draws off the battery. Best to confirm with a multimeter.
But, if you keep the REDARC connected to the battery and plugged into shore power, you'll be maintaining the battery at 100% SOC no matter if you are in Touring Mode or Storage Mode. Doing so will impact battery longevity. There are too many factors to say exactly how much of an impact, but in an off-season storage scenario, it is completely unnecessary to store at 100% since you'll not suddenly decide to take a trip like one might in-season. Storage in extreme heat (summer temps) is when storing at 100% is the hardest on lithium, but it should also be avoided in winter temps. Also very hard on Lithium to sit 100% discharged so one must be mindful of that. Their happy place is medium state of charge. Everything impacts longevity. The number of times you cycle them and how fast you charge and discharge them are also factors. But we buy them to use them and their useful life will already be very, very long for typical recreational-camper use case so babying them may not be worth it to most users. I just enjoy going that extra mile and some may not.
Per the REDARC owner's manual, on Lithium setting, both Storage Mode and Touring mode charge up to 14.5v then float at 13.6v. 13.6v is roughly 100% SOC for lithium, so too high for long term storage in my opinion. Best to have a LiFeP04 sitting at 13.1v to 13.2v when at rest ('At rest' means tested with no load and no charge for at least 30 minutes before the test. You can't use the voltage to infer SOC if there is a load or charge at the time). If you test them while in storage and they drop below 13.1v, use a little lithium battery tender to trickle a bit of juice into them to get them between 13.1v and 13.2v again or just figure you need to push about 10% or your batteries amperage into them. Easy to calculate how long to leave it on, too. If you want to add about 10% charge, look at your battery capacity (100amp in your case), take 10% (10amp in your case), then determine the amperage of you charger to get a rough idea of how many amps it push per hour. A 1amp charger will take you roughly 10 hours to raise your battery 10 amps for example which should be plenty to get you back in the middle of the happy zone of 13.1v - 13.2v. Test it later, at rest, to confirm. And again, this is being a bit picky and perhaps a bit over the top for most. If someone wants to take the simple route, at least get the SOC down to below 90% (70% to 90% for example) then disconnect cables from the terminals for storage season and let it sit there all winter. It is very unlikely it will need any charging the entire storage period. One will still do the occasional check with the multimeter, but no need to charge unless the resting voltage drops below 13.1v (or whatever the recommended minimum storage voltage is given by your lithium battery manufacturer).
Regarding REDARC Storage mode, it is important to ensure all loads are removed since Storage mode doesn't cycle like Touring mode. It runs the cycle and then sits at Float/maintenance and if you have a load drawing it down, it won't kick back on like in touring and so can drain the battery. For example, you change REDARC to Storage mode but don't disconnect all loads, come out and use the overhead LED lights and forget them on, Storage mode may not keep up (I don't recall the exact amperage of Storage Modes trickle). If it won't, your batteries will slowly drain until the BMS trips. I can see a use case for Storage Mode with AGM batteries, but I don't see a use case for Storage mode with Lithium. Well, only possible one might be if someone is storing camper and will be unable to check on it for 6 months, but I submit that it would be better for a lithium battery for the owner to get it to 90% SOC, disconnect it completely, and let sit that entire 6 months disconnected with no draw and no charge. LiFePO4 have a self discharge rate of only about 5% per month. So a 90% SOC battery will self discharge to about 60% SOC over a 6 month period and with less wear and tear than if it sat at 100% that entire time. (Again, AGM are lead acid and so the opposite is true for them. They should always be connected to a smart charger at maintained at 100% SOC all off-season).
I just pulled my CAMP-X off and am storing it in my unheated shop. We used it the night before. Before our trip I had charged to 100% SOC and let it sit there for a bit to allow for any equalization, etc. the BMS might want to do. We then used down to about 75% SOC during the trip. I did not let it recharge on the way home (flipped my under hood disconnect) and did not recharge once home. Then, run the battery down to 40% - 60% SOC and disconnect the battery cable, but left battery sitting in camper battery box. I'll check the voltage with a multimeter once a month to ensure it's still within that 13.1v - 13.2v range. If voltage falls too low, I'll add current directly to the battery with a small, lithium battery tender. I'll not charge up to 100%; I'll only charge for long enough to get back within 13.1v to 13.2 v range when at rest.
