"Anyway, this has been pointed out several times, but the same claims still get made. In general, if you want cheap then go with flooded lead acid, if you don't want maintenance, go with AGM, if you want the best lifetime value and performance go with LiFePO4. If for some reason it is really important for you to charge at -37C then go with SiO2"
The OP just wants more AH in the battery space available than he gets now with his Wets. Li and SiO2 will do that.
In my case with the previous TC, I just carried more batteries than would fit in the TC battery box, by putting them in the truck bed in front of the wheel wells and running wire inside. I would do that with the camper part way into the truck when loading and unloading the camper.
In my case the two batts had to go inside so that meant no Wets.
I did get two SiO2s for this camper, but for a reason not mentioned above. I use high amps for microwave etc with a big inverter. That takes four batteries and in a bigger RV they can be Wets, no problem. No reason at all to get Li or SiO2 if you can fit four Wets outside or vented.
With space for only two batts, you can't run the high amps with either Wets or ordinary AGMs. That leaves SiO2 or Li. I chose SiO2 because I can't afford Li, but could spring for the SiO2. I also don't like the whole BMS thing that Li has, but that is just me, so not a factor for others I suppose. I don't have to consider their weights in my scenario. The low temperature advantage of SiO2 might be a good thing where we use the TC in the winter, not sure- mostly it is above freezing here in winter but not by much at night.
On life span of the battery by number of cycles, both SiO2 and Li would be way more than we will ever do, so just not a factor. If you are 30 years old and will keep your RV for 30 years and camp often, that might be worth a look compared with Wets or AGMs, but I doubt most will ever realize that "advantage" if that is why they are buying Li. (Seems more like it is just to "keep up with the Joneses" in some cases reading rv.net posts---but some folks do have good reasons as they have explained)
So you do have to work your way through the choices to see what you need and can afford, as mentioned by FWC above, but there are more scenarios for juggling all the factors than mentioned.
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