You get diminishing returns from going up in charger amps, but with 8 batteries that won't be an issue unless you use multiple 100ampers :)
The charging amps a generator can run depends on the VA rating of the gen, not its named watts size. A Honda 3000 does 2800 VA. Also chargers can be non-Power Factor corrected or corrected. The generator can run more amps with a power- factor corrected charger drawing the same VA.
Ok, so here are some times using various size chargers on two batts so just multiply those times by four to get your eight batt times.
( You double the time with the same amps if you double the battery bank size; but you do not halve the time by doubling the amps on the same battery bank--that is the diminishing returns part of this)
