Can only speak to our own instances.....
We use our generator (loud contractor grade) at the NASCAR races in NH only. Use it to charge the batteries and run the A/C for a while if is real hot. At the race we can run the generator between 7:00 am and 11:00 pm. We try not to run all day if at all possible.
This year we found a 3500W inverter generator on craigslist for good money and will be using it in a couple of weeks at The Rally in NY - but only for charging the batteries. The rally hours are similar to the race.
I have tested this new generator running the smaller AC unit. Doesn't run the 15K A/C but runs the 13.5K without problems. This maybe enough for the NASCAR race also but will wait to see what the weather reports are for the week.
