AC Genset Showdown: Parallel Operation
July 2, 2011
Filed under Trailer News
Portable generators come in a variety of sizes, so why buy two 2,000-watt generators and run them in parallel when you can just buy one 3,000- or 4,000-watt generator? Portability. Consider that a single Yamaha EF2000iS has a dry weight of just 44 pounds, while a single 3,000-watt Yamaha EF3000iSE tips the scales at 150 pounds. Another benefit of two generators is storage; most RV storage compartments aren’t large enough for a 3,000-watt generator, but may accommodate two 2,000-watt generators. And even if both generators won’t both fit in the same compartment, they can be separated — not so with a big-boy generator.
Another reason for parallel operation is flexibility. If you just want to make a pot of coffee, you only have to pull out one small generator, not a big, heavy one. When you need to run the roof A/C, you connect two in parallel, and you’re chilling out in no time.
To see how well it works, we obtained two generators from Yamaha, as well as a parallel cable kit. Connection is a snap. The cable has a female 30-amp outlet that splits off into two separate cables, each with a positive, negative and ground wire. Plug the cables into each generator, connect the ground cables, plug in the rig’s power cord, and you’re ready.
We got the two generators humming, went inside to turn on the roof A/C. It seemed like the two generators were only working at about 50 percent, so we turned on the microwave for 30 seconds to see how the two Yamahas would handle it. Their engine speeds definitely climbed, but the units didn’t seem to be struggling at all, and the lights never so much as dimmed inside the coach.
Of course, not all coaches have the same air-conditioning units (or microwaves for that matter) so it’s important to find out how many watts your roof A/C, microwave, and anything else you want to run draws before you purchase any generator. Generac, Honda and Yamaha all offer guides for correct generator selection based on what appliances you use.
The Yamaha twins could power up the roof A/C and microwave oven and didn’t seem to struggle, nor did the coach lights dim under the draw.