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Firman H03655 vs DuroMax XP4850HX

Firman H03655 vs DuroMax XP4850HX

Comparing the Firman H03655 and DuroMax XP4850HX dual-fuel generators. See how runtime, power output, weight, and warranty differ for your needs.

  • DuroMax XP4850HX
  • Firman H03655

Comparison Overview

The Firman H03655 and DuroMax XP4850HX are both conventional dual-fuel generators that run on gasoline or propane, but they split on power, runtime, and warranty in ways that matter depending on your situation. The DuroMax XP4850HX delivers 3850 running watts and 4850 starting watts, giving it a meaningful edge over the Firman's 3650 running watts and 4550 starting watts. That extra 200 running watts can be the difference between comfortably powering a window AC unit alongside other appliances or tripping the overload.

Where the Firman fights back is weight and runtime at half load. At 112 lbs, it's 14 pounds lighter than the 126 lb DuroMax, which matters if you're loading it into a truck bed regularly. The Firman also runs for 14 hours at 50% load compared to the DuroMax's 10 hours, so you'll refuel less often overnight. However, the DuroMax offers an impressive 23 hours at 25% load, making it a strong pick for lighter, extended use. Noise levels are close, with the Firman at 67 dB and the DuroMax at 69 dB.

The DuroMax comes with a 5-year warranty versus the Firman's 3-year coverage, which adds peace of mind for long-term ownership. Buyers who prioritize efficiency and portability may lean toward the Firman, while those who want more power headroom and a longer warranty may prefer the DuroMax.

Key takeaways

  • DuroMax XP4850HX provides 3850 running watts, 200 more than the Firman H03655's 3650
  • Firman H03655 runs 14 hours at half load versus the DuroMax's 10 hours
  • DuroMax XP4850HX offers a 5-year warranty compared to Firman's 3-year coverage
  • Firman H03655 weighs 112 lbs, making it 14 pounds lighter than the DuroMax
  • Both generators are dual-fuel, running on gasoline or propane for flexible refueling
  • DuroMax XP4850HX achieves 23 hours of runtime at 25% load for light-use scenarios

Best use cases

Choose the Firman H03655 if you need a generator that's easier to move around and sips fuel more slowly during sustained use. At 112 lbs, it's noticeably lighter, which makes a real difference when you're lifting it in and out of a vehicle or repositioning it around a property. Its 14-hour runtime at half load is ideal for overnight home backup during a power outage, letting you keep the refrigerator, lights, and a few essentials running without getting up to refuel at 3 a.m. The slightly lower noise level of 67 dB is a small but welcome bonus if neighbors are close by. Just keep in mind that with 3650 running watts, you'll need to be more careful about what you plug in simultaneously. Running a large window AC unit, a refrigerator, and a microwave at the same time could push it to its limits.

Choose the DuroMax XP4850HX if you want more power headroom and plan to keep this generator for years. The 3850 running watts and 4850 starting watts give you a comfortable buffer for demanding loads, including larger appliances with high startup surges. The 5-year warranty is a significant advantage, essentially giving you two extra years of manufacturer-backed coverage compared to the Firman. The 23-hour runtime at 25% load is also exceptional for scenarios where you're running just a few lights and charging devices during an extended outage or a long weekend of camping. The tradeoff is the extra 14 pounds and a shorter runtime at half load (10 hours versus 14), so if you're consistently running heavier loads, you'll be visiting the fuel tank more often. Neither generator is an inverter model, so avoid plugging in sensitive electronics like laptops directly without a surge protector or separate inverter.

Verdict & recommendation

These two generators occupy very similar territory, and neither is a clear-cut winner across the board. If your priority is fuel efficiency at moderate loads and easier portability, the Firman H03655 earns its keep with a lighter frame and longer half-load runtime. If you want more watts on tap and the reassurance of a longer warranty, the DuroMax XP4850HX is the stronger choice, especially for home backup scenarios where you might need to power multiple appliances with high startup demands.

Both are solid dual-fuel options in the mid-range portable category. Your decision should come down to whether you value the extra power and warranty coverage of the DuroMax or the lighter weight and better fuel economy of the Firman.

Last updated March 21, 2026

  • Model XP4850HX
    Model XP4850HX

    DuroMax 3,850W Dual-Fuel Generator

    3850W
    Running
    69 dB
    Noise
    View details
  • Model H03655
    Model H03655

    Firman 3,650W Dual-Fuel Generator

    3650W
    Running
    67 dB
    Noise
    View details
Quick charts
Each chart uses its own Y-axis scale (so numbers are comparable within a chart).
Running watts
W
Starting watts
W
Noise
dB
Runtime @50%
h
Running watts by fuel
Shows how output changes across gasoline/propane/natural gas (when available).
Generator Specifications Comparison
SpecificationDuroMax XP4850HXFirman H03655
General
Product type
Generator
Generator
Fuel
Dual-Fuel
Dual-Fuel
InverterNoNo
Parallel capableNoNo
RV readyNoYes
Running watts
Winner: Winner: 3850 W
3650 W
Starting watts
Winner: Winner: 4850 W
4550 W
Noise (lower limit)
69 dB
Winner: Winner: 67 dB
Weight
126 lbs
Winner: Winner: 112 lbs
Run time @50% load
10 h
Winner: Winner: 14 h
Run time @25% load
23 h
Not available
Fuel tank
4 gal
5 gal
Fuel gaugeYesYes
Approx. dimensions (L × W × H)
23 x 25 x 22
25.7 x 21.8 x 21.6
Electrical
Voltage (AC)
120
120V 60 Hz
Voltage (DC)
5
Not available
GFCI outletsYesNo
Covered outletsNoYes
Automatic Voltage RegulationYesYes
THD
Not available
25 %
Engine
Engine
210 cc OHV 4-stroke, cast iron sleeve
208 cc OHV 4-stroke, cast iron sleeve
Alternator
Not available
Not available
Starting system
Recoil, Electric
Recoil
Warranty
Warranty
5 years
3 years
Power by fuel
GasolineNot availableNot available
Running watts
3850 W
3650 W
Starting watts
4850 W
4550 W
Running amps (120V)
Not available
Not available
Running amps (240V)
Not available
Not available
Peak amps (120V)
Not available
Not available
Peak amps (240V)
Not available
Not available
Run time @50% load
10 h
14 h
Run time @25% load
23 h
Not available
PropaneNot availableNot available
Running watts
3650 W
3300 W
Starting watts
4600 W
4100 W
Running amps (120V)
Not available
Not available
Running amps (240V)
Not available
Not available
Peak amps (120V)
Not available
Not available
Peak amps (240V)
Not available
Not available
Run time @50% load
9 h
Not available
Run time @25% load
18 h
Not available
Other
Data center
Not available
Not available
Indicators
true
false
Compliance
CARB, EPA
EPA, ANSI/PGMA G300-2023
Security
Not available
Not available
Spark arrestorYesYes
Neutral
Not available
Floating
UPC
811640016197
840876136553
Core / High-priority specs
Running Watts (Gasoline)
3850
3650
Running Watts (Propane)
3650
3300
Starting Watts (Gasoline)
4850
4550
Starting Watts (Propane)
4600
4100
Runtime @ 50% Load (Gasoline)
10
14
Runtime @ 50% Load (Propane)
9
Not available
Runtime @ 25% Load (Gasoline)
23
Not available
Runtime @ 25% Load (Propane)
18
Not available
AC Outlet Types
1x Duplex 120V 20A (5-20R) GFCI; 1x 120/240V 30A (L14-30R)
1x Duplex 120V 20A (5-20R); 1x 120V 30A (L5-30R); 1x 120V 30A (TT-30R)
Electrical & power
Frequency
60
60
Engine & construction
Engine Type
OHV 4-stroke
208 cc OHV 4-stroke, cast iron sleeve
Engine Displacement
210
208
Cylinder Sleeve
cast iron sleeve
cast iron sleeve
Alternator Winding Material
Copper windings
Not available
Engine Oil Type
10W-30
Not available
Runtime & fuel system
Runtime @ 25% Load (Gasoline)
23
Not available
Runtime @ 50% Load (Gasoline)
10
14
Runtime @ 50% Load (Propane)
9
Not available
Safety & compliance
Overload Protection System
Low oil and overload protection, CO monitoring
Low oil and overload protection
Low Oil ProtectionYesYes
Carbon Monoxide MonitoringYesYes
Included equipment
Mobility Components
Yes
Not available
Starting Components
battery
Oil, funnel, tool kit, propane hose, and wheel kit
Included Accessories
Funnel, tool kit, propane hose, battery, and wheel kit
Oil, funnel, tool kit, propane hose, and wheel kit
Warranty & identification
Residential Warranty
Not available
3
Commercial Warranty
5
3
Additional specs
Summary
The DuroMax XP4850HX is a dual-fuel generator with a rated wattage of 3850 watts and a peak wattage of 4850 watts. It features both recoil and electric starting options.
The Firman H03655 is a 3,650-watt dual-fuel generator built around a 208 cc OHV 4-stroke engine with a cast iron sleeve. Running on gasoline, it delivers 4,550 starting watts and 3,650 running watts. Switch to propane and output drops to 4,100 starting watts and 3,300 running watts. This power level runs a refrigerator, microwave, window air conditioner, or multiple power tools simultaneously. The dual-fuel flexibility means you can operate on whichever fuel is available, a practical advantage during extended outages or when propane storage is more convenient than gasoline. At 67 dB at quarter load, the H03655 operates quietly enough for residential neighborhoods without disturbing neighbors. The 5-gallon tank delivers 14 hours of runtime at 50 percent load on gasoline, translating to roughly one full day of moderate use before refueling. The RV-ready configuration and included wheel kit position this unit as a go-anywhere power source for camping, job sites, and home backup scenarios.
  • Most Powerful
    DuroMax XP4850HX
    3850W running
  • Quietest
    Firman H03655
    67 dB
  • Longest Runtime
    Firman H03655
    14h at 50% load
Where to buy
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DuroMax XP4850HX
Store links
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Firman H03655
Store links
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