While it's true that the inverter gens aren't much quieter than a synchronous gen while under a heavy load (NOR are they any more fuel efficient than a synchronous in that situation either)...
...One thing that should be kept in mind, is that a battery charger doesn't run at full load the whole time.
Let's use a 25a Iota for example...
The Iota with IQ/4 will do a bulk stage (constant current) for up to 4 hours, then drop to absorb. After dropping to absorb, the amperage flowing to the battery - and thus the load on the generator - then tapers off over time.
Without the IQ/4 module, it's just a two-stage charger and will bulk the battery up to 14.4v and then drop to float.
So even if a 25a charger maxed out a 1000i *at first* - it'll only be for a couple hours and then as the charge current tapers off, the inverter's RPM will start dropping, and the noise will start reducing (and the fuel consumption will get better).
At which point, the inverter gen is now doing what it's supposed to - running quiet and saving fuel.
For running nothing but a battery charger, the inverter gen is likely going to spend more time down at low RPM than it will up at high RPM.
The charger I have in my camper is just an old 10a Shauer constant voltage charger. Running it off the Honeywell, the gen never got above idle and would run 14 hours on 1.5g of fuel. Running if off the little 1200w Champ sync, the gen still runs 12 hours on 1.2g of fuel.
I plan to replace it some day with a 15a Samlex configured in two-stage mode, and I doubt very much that a 1000i is going to spend much time at all at full RPM - if it ever does.
(And I don't watch TV so that's a non-issue for me. (According to the U.S. Department of Education official statistics, 50% of adults in the U.S. read at an 8th grade level or below (a.k.a., fools). Guess what group most television programming and advertising is targeted at? Ugh. I'll pass. Haven't owned a boob tube for decades and don't miss it at all.)
What I take in the (Class B) camper (van) is a netbook computer (with 12v adapter), a small DVD player (12v adapter), an electric toothbrush (2 AA batteries with a 12v charger for the batteries), a Braun electric shaver (also 2 AA batteries) and a couple of Ryobi 18v battery tools for which I have the charger that plugs into the cigar lighter socket (I use the flashlight all the time).
The only other loads are lights and water pump. EDIT: And a couple of 12v fans. EDIT 2: And a 12v charger for the phone.
Everything runs off the aux battery, so all I need a generator for is to charge that battery. I wouldn't even need it for that, but I'm the sort who will stay in a place I like for a week at a time without ever starting the truck, and with a single 100ah aux battery, that's long enough to need to charge it.)
