Can I Use the Onan QG 4000 CU64FR to Power My Keystone Passport 239ML With a Soft Start Installed?

Updated 07/02/2025 | Published 06/17/2025

Products Featured in This Question

Onan Generator - Quiet Series 4000 EVAP Onboard RV Generator - 4,000 Watts - Gasoline

(2)

$4426.24

Onan Generator - QG 4000i EVAP Onboard RV Generator w/ Inverter - 4,000 Watts - Gas - CARB Compliant

(3)

$4849.62

Question:

I have a 2023 Keystone Passport 239ML with a 13.5K BTU Dometic A/C and a SoftStartRV already installed. I’m hoping the QG 4000 gas generator will be enough juice to run the A/C and maybe a microwave. Will part CU64FR work, or should I look at something larger?

asked by: Meredith

Expert Reply:

You’re on the right track! The QG 4000 # CM32ZR is one of our most popular setups for small to mid-size travel trailers like your Keystone Passport 239ML — and with that SoftStartRV unit on your 13.5K BTU Dometic, you’re golden.

We've heard from customers running setups nearly identical to yours shoutout to Kevin in Tucson and Mary in Arkansas! who say it handles the A/C like a champ, even with the fridge or a few outlets in use. Just make sure your A/C startup draw and other electronic draw stays below the generator’s 33.3A peak.

Onan also has an inverter model # CM42ZR which is identical to the one mentioned above, aside from this one having a built-in smart inverter for more sensitive electronics like laptop and phone chargers, smart TVs, Wifi routers/boosters, CPAP etc. But if your RV already has a good inverter built-in that can handle your sensitive electronics, then the inverter model won't be necessary.

Planning to boondock in warmer climates? Let me know your route and I’ll help you confirm real-world runtime based on elevation and temps.

expert reply by: Andrew N

Meredith

7/2/2025

Thanks for the confirmation! Would adding a second A/C unit in the future require a larger generator, or could the QG 4000 handle it with the SoftStartRV units?

Andrew N.

7/2/2025

@Meredith You're welcome, Meredith! Adding a second A/C unit would increase the load, and while SoftStartRV units help reduce startup power demands, the QG 4000 may work but it will be very close to its limit. For optimal performance and to avoid overloading, we recommend considering a generator with higher wattage if you plan to run both A/C units simultaneously.