Originally Posted by usmc2
This may seem obvious, but I'm thinking of getting a generator for some light use when away for multipul days. Do I need to have a generator/invertor if I am plugging the SMB direct to the unit?
You do have an onboard inverter/charger and house battery system correct? Most generators have a 12vDC charger output as well as the AC output. If you don't have a inverter/charger or converter/charger you'll have to rig a cord from the generator to tie in with the 12vDC system or simply run a car charger off the vans AC system after you've plugged into the shore power outlet.
With my inverter, if I plug in a cord from a generator to the shore power inlet on the van, I use the inverter to charge my house batteries. Most of the better built-in inverters have this function but the small standalone type usually don't. The battery system actually supplies the DC portion on my van so I can actually use a smaller generator and cord to charge the batteries. Like Mike posted, It wouldn't be a problem to run light load AC devices while even supplying a light battery charge.
But depending on the load you plan to pull, a small 500 watt generator might trip out if the inverter switches into the AC mode and the AC load is greater than 500 watts. Most microwaves range between 650 and 1200 watts. Some small electric heaters or hair dryers can pull 1500 or more so depending how you use the generator, it's possible you might have to size the generator and cord to your load.
Some vans don't have inverters but come with a converter/charger. The end result is the same, the converter will charge the house battery system and also supply DC voltages while plugged in to shore power. I've also seen a few vans with no house battery system and the converter supplies the living area DC while the shore power supplies the AC outlets but those are rare.
Hope this helps