Linking two small generators sounds like a flexible option. The owner manuals tell a different story, and for most Australian caravanners the decision is settled before you reach the price tag.
Between the fridge, lights, coffee machine, and air conditioner, it is easy to reach the limits of a caravan’s generator. That leaves a practical choice: do you buy two smaller inverter generators and connect them in parallel, or choose one larger unit that can handle the load on its own?
Using two smaller generators can offer more flexibility. You can carry one for lighter loads and connect the second when you need more power. But not every generator supports parallel operation, so always check the manufacturer’s specifications and manual first.
Here’s what parallel operation involves, which generators support it, and what to consider when choosing between two smaller units and one larger generator.
» MORE: Compare the full Outbax inverter generator range
What Running Two Generators in Parallel Actually Means
Parallel operation links two compatible inverter generators through dedicated parallel outlets and a purpose-built cable, so the pair behaves as one supply.
The Gentrax GTX4200 Pro Inverter Generator lists parallel outlets as a control-panel component and lays out the sequence. Connect the cable, start both generators separately, wait for a green output light on both, then connect your appliance. Shutting down runs in reverse: disconnect the appliance, stop both engines, then disconnect the cable. The manual is explicit: never connect or disconnect the cable while the engines are running.
Three rules in that section matter more than most buyers realise.
Same model only: parallel running applies to two units of the same model fitted with the parallel function. Connecting a generator in parallel with mains electricity or with a different generator is prohibited.
Ninety per cent, not one hundred: the parallel rated output is 90% of the two generators’ combined rated output. Two units rated at 3.5kW each supply 6.3kW of continuous power, not 7kW.
Economy switches move together: the economy control on both units has to be switched on or off at the same time.
Here’s what one of our customers said about the Gentrax GTX4200 Pro Generator:
“Fantastic product especially if you are a woman who just needs the basics. This is a top quality easy to operate machine. And it’s pretty. I love how it looks.”
Most Inverter Generators Cannot Be Paralleled at All
This is where the marketing and documentation parts of the company diverge. Across current Gentrax manuals, only one model documents a parallel function.
The GS-6500IE manual covering the GTX6600 instructs owners to avoid connecting the generator in parallel with any other generator, and the GSI-950 manual for the GT800 Pro carries the identical line. The GSI-BXBE manual for the GT2000 and the GSX-CEDD manual for the GTX3500 list every control, socket, and outlet on the unit, and neither list includes a parallel outlet.
| Model (manual code) | Max output | Rated output | Fuel tank | Parallel function in the manual |
|---|---|---|---|---|
| Gentrax GT2000 (GSI-BXBE) | 2.0kW | 1.7kW | 4.1L | No parallel outlet listed |
| Gentrax GTX3500 (GSX-CEDD) | 3.5kW | 3.2kW | 7.5L | No parallel outlet listed |
| Gentrax GTX4200 Pro (GS-4000IE) | 4.2kW* | 3.5kW* | 8.8L | Parallel outlets fitted, cable required |
| Gentrax GTX6600 (GS-6500IE) | 6.6kW | 6.0kW | 18.5L | Manual advises against parallel use |
Figures from the Gentrax owner manuals. *Output figures for the GTX4200 Pro are from the Outbax product listing. Specifications change, so check the manual supplied with your unit.
The takeaway is simple. If you already own a generator and you are thinking about a twin, open the components page of your manual before you spend a cent. No parallel outlet means no parallel option, and the conversation moves to sizing a single unit properly.
» MORE: Browse 2kW inverter generators
Here’s what one of our customers said about the Gentrax GTX6600 Generator:
“Works well, starts super easy every time. I just bought a second one!! :)”
Size on Rated Output, Not the Headline Number
Every inverter generator has two output figures, and they aren’t interchangeable. Maximum output is a brief surge figure. Rated output, sometimes called continuous output, is what the unit holds hour after hour. The Gentrax manuals are blunt about which one governs: the total load must sit within the rated power, and exceeding the rated load will damage the unit or shorten its life and will invalidate the guarantee.
Air conditioners complicate that, because a compressor draws far more current at start-up than it does once running, commonly two to three times the running figure. Read the compliance plate on your own unit rather than trusting a general number.
Three details from the manuals change how you size and run the generator.
Switch economy mode off before the compressor starts: both the GS-4000IE and GS-6500IE manuals say to turn off the economy control for devices with a large starting current, such as compressors and submersible pumps. Turn it back on once the compressor settles.
Expect the overload light at start-up: when an electric motor starts, the red overload indicator and the green output indicator can light together for about four seconds, which the manuals describe as normal. If the red light stays on, reduce the load and press the output reset.
Allow for the break-in period: a new Gentrax unit has a break-in period of about 25 hours, during which the manual says not to exceed 75% of rated capacity. On a 3.2kW rated generator, that is roughly 2.4kW, and an oil change falls due at the end of it.
» MORE: Read the Outbax generator buying guide
Where a Parallel Pair Wins, and Where One Larger Unit Wins
The trade-off comes down to how you load, store and service the equipment.
The Case for Two Smaller Units
A lighter single lift: the Gentrax GT2000 weighs 18.5kg. The GTX3500 weighs 37.5 kg, and the GTX6600 weighs 89kg, a unit you roll on its wheels rather than lift into a boot. If loading a generator on your own is the limiting factor, two small units solve a problem extra output cannot.
Output that scales with the day: run one unit for the fridge, lights, and chargers, and start the second only when the air conditioner goes on.
A spare engine: if one unit will not start in a remote spot, you still have power for the essentials.
The Case for One Larger Unit
All the output, none of the derating: no 90% rule, no matching-model requirement, and no special cable to lose.
One tank and one service schedule: the GTX6600 holds 18.5L and the manual quotes 4 hours 30 minutes at full load. A pair means two tanks, two oil changes, two air filters and two spark plugs.
More noise, not less: two engines running side by side produce more sound at the same distance than one. Outbax lists the GTX4200 Pro and the GTX6600 at 62 dB at seven metres, and the GT2000 at 60 dB, so a pair isn’t the quiet option in a park with a limit.
Five Checks to Make Before You Buy Either Setup
Confirm the parallel function in the manual, not the marketing. Look for parallel outlets on the components page and a parallel procedure in the operation section, then confirm the cable is available for your exact model.
Compare rated outputs, not headline figures. Line up your shortlist by continuous output, then add headroom for the air conditioner start-up load.
Check the noise figure and the distance behind it. Gentrax units are quoted at seven metres, so a figure measured elsewhere is not comparable. Parks and reserves set their own limits and quiet hours, so confirm with the operator or land manager.
Look for the Regulatory Compliance Mark. The GSI-BXBE and GSX-CEDD manuals carry the RCM statement and reference the Electrical Equipment Safety System. It separates compliant stock from grey imports, and it matters for warranty.
Read the safety section before the first start. Never run a generator in an enclosed or unventilated space, including a tent or the caravan itself, because exhaust fumes cause carbon monoxide poisoning. Keep it at least one metre clear of buildings and equipment, never against canvas or plastic, earth it, refuel only with the engine stopped and cool, and never run it in rain. The manuals also prohibit connecting it to any other electrical source.
» MORE: Find model-specific generator parts and accessories
Match the Setup to the Way You Actually Travel
If the air conditioner is why you are shopping, a single unit sized on rated output with sensible headroom is the simpler answer, and across most of the Gentrax range it is the only answer the manual permits. A parallel pair earns its place in one situation: you want the lightest possible single lift, you are buying two identical units with the parallel function, and you accept two engines to run and service.
Work out your rated load, open the manual, then choose. The Outbax team can talk through your appliance list if you want a second opinion on the numbers.
