How Long Will Flex Power 3300i Run At 50% Load
Updated 07/24/2026 | Published 07/23/2026
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Question:
All the generators I have ever looked at always mention how long a tank of fuel will last based on half load. I noticed that I cant find this information anywhere for this one. Is there any info on this available? Who makes the engine? I currently have a Generac 2500I and it wont run my a/c even with the softstart and everything else turned off and want to make sure the 3300 will run it. I have a dometic a/c on a 2014 Keystone Passport ultra lite 25ft
asked by: Paul
Expert Reply:
Hey Paul! That's a great question. The Flex Power 3,300-Watt Portable Inverter Generator # FP54FR will run for 5-6 hours at 50% load, 7-9 hours at 25% load. This uses a 149cc OHV engine from RV Mobile Power (RVMP). RVMP does not publish who manufactures the engine, so it appears to be an in-house branded design rather than an engine marketed under another manufacturer's name
As for your Dometic AC, the # FP54FR provides 3,300 starting watts and 2,700 running watts, which is a significant step up from your Generac 2500i. With a SoftStart installed and the other major loads turned off, it won't have a problem running a typical 13.5K BTU Dometic AC.
Any big trips coming up with your 2014 Keystone Passport?
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Flex Power 3,300-Watt Portable Inverter Generator - Gas - Manual Start - 30 Amp RV & 120V GFCIs
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Paul
7/23/2026
I might be heading for either florida or AZ in oct. Either one requires an a/c unit during the day. This generator seems to be a bit more thirsty than my generac. It is worth a bit being able to run my a/c in the summer and it is a little bit lighter in weight. I did notice the 4400 only held a half gal more fuel than the 3300. Does than even get it 8 hrs under 25% load? Just want to make sure I get a generator big enough that doesnt make me feel like its being made by opec and does the job.