I have had a 300AH 'SmartBattery' Lithium Battery in my coach for almost 2 years. Each cell is sealed stainless steel, so no fire risk. Integrated electronics controls contained inside the battery case manage both charge and discharge functions. We upgraded the Magnum Inverter software (by replacing the circuit board to the latest version) to maximize the control over the system and this allowed us to customize settings to the battery.
We can easily go an evening with TV and Satellite use (3+ hours), with ample LED lights on, then in the morning we can use an electric coffee maker to brew a carafe of coffee. Our engine alternator (160 amp) charges the battery in about 1.5 hours. If it is really low and we are not driving, the generator powering the inverter/charger (100 amps) will run 2.5 to 3 hours max to bring it up to fully charge (which is about 1/2 the time it took with the AGM original batteries). We regularly dry camp and have never run out of power taking reasonable measures to reduce current drain.
I'd go for a smaller amp-hour capacity (300-400AH) and spend time optimizing the system. Your fridge draws less power than the electric heaters in an absorption fridge and depending upon your solar panel setup, you could almost eliminate generator use. We looked at the economics of installing solar versus use of the diesel generator and the case is definitely in favor of using the generator for dependable power unless you can angle the panels to the sun and are in an area that gets a lot of consistent sunlight each day.
Granted there are different thoughts about generator vs solar (green energy and all) however your initial outlay sounds very high for the perceived benefits. I doubt that we'll ever change the coach battery in this coach and the additional volt of consistent power increases the water pump pressure and certainly makes the onboard systems more efficient. If you want to read about our installation check out our TechTips #82-84 at www.rv-partsplus.com
Good luck with the conversion!
