Cummins Onan P2500i vs Westinghouse iGen2550c

Comparison Overview

Analysis by AJ Quick

Mechanical engineer and founder of RightGenerator

Key takeaways

• Cummins Onan P2500i delivers 2200 running watts, 400 more than the iGen2550c's 1800
• Westinghouse iGen2550c weighs just 40 pounds, 8 pounds lighter than the P2500i
• Both generators produce 52 decibels, quiet enough for campground use
• Westinghouse iGen2550c runs 11.5 hours at 25% load, outlasting the P2500i by 1.5 hours
• Both include inverter technology and a 3-year warranty

Best use cases

Choose the Cummins Onan P2500i if you plan to power more demanding appliances or need a comfortable buffer of running watts. With 2200 running watts, it can handle a small RV air conditioner, a full-size refrigerator, or multiple devices running simultaneously without straining. It's a solid choice for RV owners who want reliable climate control, tailgaters running TVs and blenders at the same time, or homeowners looking for emergency backup power that can keep a fridge and a few lights going during an outage. The tradeoff is an extra 8 pounds of weight and slightly shorter runtime per tank, but for many buyers the added power capacity is well worth it.

Choose the Westinghouse iGen2550c if keeping things light and stretching every gallon of fuel is your priority. At 40 pounds, it's easy enough for one person to carry without much effort, which matters a lot on hiking-adjacent campsites or when you're loading gear solo. The 11.5-hour runtime at 25% load means you can run lights, charge devices, and power a small CPAP machine through the night without refueling. It's an excellent companion for tent camping, car camping, or as a lightweight backup for charging essentials during short power outages. Just keep in mind that the 1800 running watts will limit you if you try to run high-draw appliances like air conditioners or microwaves.

Both generators are quiet enough for campground use and produce clean power for electronics. The real question comes down to whether you value raw power output or the combination of lighter weight and longer runtime.

Verdict & recommendation

These two inverter generators score within a hair of each other overall, and for good reason. They share the same noise level, the same warranty, and similar starting wattage. The deciding factor is straightforward: if your priority is running watts and the ability to power larger appliances, the Cummins Onan P2500i's 2200 running watts give it a clear practical advantage. If your priority is portability and fuel efficiency, the Westinghouse iGen2550c saves you 8 pounds and adds roughly 90 extra minutes of runtime per tank at light loads.

For RV use or home backup where you need to run a fridge or small AC unit, lean toward the P2500i. For camping trips, solo adventures, or light-duty charging needs where every pound counts, the iGen2550c is the smarter fit. Neither is a wrong choice, just a different one depending on how you plan to use it.