If one buys a top of the line fully charged large battery and then connects say a 1200 watt inverter to it. Then from the inverter I connect a trickle charger back to the battery.
You've got the battery powering the inverter, and you plug a trickle charger into the inverter to keep the batteries charged?
"Question one: will the battery stay fully charged or will the drain from the inverter alone cause the battery to lose it's charge?"
Well, even in the inverter were 100% efficient, it would draw more power from the battery than the battery can absorb in a charge, so no, the battery won't stay charged at all.
Inverters are a little more efficient than most people think. Most of the el cheapos are 90% efficient at partial load (up to 50%) and around 95% efficient at a full load. The higher end ones are up to 98% efficient. But the general rule of thumb is to figure a 10% loss when going through an inverter.
Also, depending on the inverter, a no-load draw from the inverter (inverter powered on, but nothing plugged into it is drawing power) can draw anywhere between .2 and 1.0 amps from the battery.
"Now, assuming the battery will stay fully charged. Now we add one appliance that takes say 600 watts to run and we occasionally use this for say 6 hours at a time."
Amps x volts = Watts.
Watts divided by either one gives you the other, as in:
Watts / volts = amps
When dealing with batteries, it's the amp hour capacity that's important, and the amp draw, so when you say watts, you must convert that to amps to mean anything. 600 Watts at 120 volts AC, or 600 Watts at 12 volts DC?
A 600 Watt AC appliance at 120 volts draws 5 amps AC. Through an inverter the same 600 Watts as 12 volts DC draws 50 amps plus 10% for the inverter loss, so figure 55 amps.
55 amps off a battery is a hefty draw. At 6 hours, that's 330 amp hours. And that doesn't even take the Peukert Effect into account, which is akin to speed and MPG, the faster you go the less miles per gallon you get, and with amp draws, the higher the amp draw the less amp hour capacity the battery has.
For example, a 350 amp hour battery at a 5 amp draw will have a total capacity of 497 amp hours, since the Peukert "corrected amps" will be about 3.5 instead of 5.
Same battery at a 10 amp draw will have 409 amp hours of capacity. At 25 amps it will have 316 amp hours, and at 55 it will have 253 amp hours of capacity, with the Peukert corrected amps being 75.79 amps nstead of 55.
"Question two: will one battery handle this with the above mentioned setup?"
Since you don't want to discharge a battery more than 50% without
fully recharging it between discarges, because doing so will dramatically shorten its lifespan, you would need a battery with a minimum of 740 amp hour capacity. A 55 amp draw on a 740 amp hour battery would yeild 662.26 effective amp hour capacity, and half that would give you your required 330 amp hour draw and stay at 50% Depth of Discharge.
So, yes, one battery would handle it, but I have a feeling that you'd have to redefine what you mean by "top of the line", as to get a single 740 amp hour battery you really and truly are looking at top of the line, special use industrial batteries. Rather than one battery, you're looking at a system of 2-cell batteries, 6 of them, each weighing in at probably 300 pounds and costing somewhere in the neighborhood of 2 grand per, so about $12,000 for the battery.
A more cost effective setup would be two pair of 6-volt batteries, like the
Discover Energy EVL16-A-A AGM 6-volt batteries that, once hooked together in pairs, effectively making each pair a 6 volt battery, each pair would give you 390 amp hours (roughly 385 minutes of discharge at 55 amps). And then hook those together is parallel to increase amps to 780 amp hours.
But that's assuming that you won't be running anything else off the batteries at all, ever. If you do, that's more amp hours gone, and thus would require probably a third pair of batteries. These batteries are, I think, in the $500 each range. So one pair to make 12 volts is about a grand.
These batteries also weigh about 130 pound each, so 260 pounds per pair. So that may be a consideration.
Plus batteries like AGM, gel and other advanced types require special charging parameters that must be closely monitored. Most cranking batteries and AGM house bank batteries require different charging voltages and amp currents, for example.
600 Watts for 6 hours. That sounds like you want to run some kind of resistive heat appliance, like a 120-volt electric heater or an air conditioner. These kinds of appliances, also clothes dryers, dish washers, etc., do not get along with and play well with 12-volt batteries. Not at all. Best to use shore power or a generator for that.
Question three: Where is a good source for information about a setup as discribed above?
I have no idea. What we do out here on the road has similar requirements of alternative energies like solar and wind powered homes, and somewhat like RVers, more specifically boondockers who aren't tethered to shore power, but we have more in common with sailboats, actually.
