Honda Outback Petrol Engine with Alternator

[Smooth Cruiser]

Has anyone had any experience with a petrol engine driving an alternator for use for battery charging.

I am looking at the Honda Outback range which has 55A, 80A and 120A versions like this.

55 Amp

80 Amp

120 Amp

It seems from the specs that the 55A is only suitable for 1 N70 battery and the 80A is suitable for 2 while the 120A should obviously suit more.

I have 480 Ah of house banks that I want to charge so probably need to be looking at the 120A.

I am looking at this over a 240V generator running a 240 V 50A battery charger as it looks to be a cheaper and simpler option. Drawbacks that I can see are 1) that it is likely to be noisier as it doesn't have a sound insulating box like a portable generator 2) a generator can be used for any other 240V requirements where this only charges batteries.

The last point doesn't worry me but the first point (noise) might.

Any real world experience with these units:
-what battery bank capacity and what size alternator do you have.
-what is the noise like.
-what actual charge delivery rate do you see.

Cheers