Hyundai HY3750i: 3000W Petrol Inverter Generator

The Hyundai HY3750i is a petrol inverter generator with a continuous output of 3000W, a maximum output of 3300W and a 230V pure sine wave supply, built to run household essentials during a power cut¹. It has two 13A BS sockets, a 7.5L fuel tank and a recoil start, and the distributor gives a run time of 14 hours at 10% load¹. It is no longer sold new: the distributor's product page listed it as sold out when checked on 25 October 2026¹. This page is therefore for households who already own one, or who are considering a secondhand machine and want to know what it is, what it can do and how to use it safely.

What it suits is modest, steady loads: the distributor describes the output as enough to run a combination of lighting, a fridge, device chargers, a television and small appliances¹. That is the shape of a typical outage, and it is where an inverter generator earns its place. The inverter produces a pure sine wave, which is the smooth kind of mains supply electronic equipment expects, and inverter machines are generally lighter and more compact than conventional generators¹. It is not a whole-house machine, and it must never be run indoors.

What the HY3750i is and what it can run

The HY3750i is an open-framed inverter generator powered by a 208cc four-stroke, air-cooled, single-cylinder petrol engine¹. It is a single-phase machine producing 230V at 50Hz, which is the standard UK domestic supply, so ordinary household appliances plug straight in¹. The two 13A BS sockets on the control panel take standard UK three-pin plugs¹.

The distinction that matters for a household is between continuous and maximum output. Continuous output is what the machine can supply hour after hour: 3000W¹. Maximum output is the short burst it can deliver, 3300W, which is what covers the surge when a motor starts¹. A fridge compressor, for example, draws far more in its first second than while running. If you are unsure how a particular appliance's surge compares with these figures, the guide to watts, watt-hours and surge explains the arithmetic.

In practice, the distributor's own description is a useful guide to what the machine is for: lighting, a fridge, device chargers, a television and small appliances, run as a combination¹. Add up the running watts of everything you want on at once and keep the total under 3000W, leaving headroom for surges. The guide to deciding what to keep running helps you choose the order.

Specifications

The table below sets out the distributor's published figures for the HY3750i. Where a specification is not listed, it is not given here.

Two of these figures are given differently on the distributor's own page. The run time is given as 14 hours in one place and 5.8 hours in another, and the noise level as 72 dBA in one place and 66 dB(A) in another; the two figures disagree and neither has been ruled on. Treat both as indicative and check the manual that came with your machine. The 14-hour figure is at 10% load, which is a light load: at half load the fuel consumption figure of about 1.29 L/hr implies a much shorter run on a 7.5L tank¹.

Run time and fuel use

Run time depends almost entirely on load. The distributor gives 14 hours at 10% load and approximately 1.29 litres per hour at 50% load¹. Those two figures describe very different ways of using the machine: a few lights and a phone charger will last most of a day, while a fridge, television and small appliances together will empty the tank far sooner. The guide to how long a generator runs on a tank sets out how to estimate your own figure.

The HY3750i has no eco mode: the distributor lists ECO Mode as No¹. The engine therefore runs at a set speed regardless of what is plugged in, so unplugging a appliance does not save fuel while the machine is running. The practical response is to run it in blocks: start it, run what you need, then switch it off. That also reduces noise and hours against the warranty.

For comparison, other makers publish their own figures on their own machines. One maker lists a 5L tank running about 6 hours at 500W on a different model³, and Honda's buying guide describes a medium generator as giving up to three hours running time⁴. These are not HY3750i figures and are given only to show how much run time varies with tank size and load.

Starting, fuelling and oil

The HY3750i starts by recoil: a pull cord, with no electric starter¹. Honda's guide describes recoil start as manual engine start, and notes that some generators offer electric and recoil start together⁴; the HY3750i is the manual kind only. Before pulling the cord, read the manual that came with the machine and follow its starting sequence.

It runs on petrol and takes SAE 10W30 engine oil, with an oil capacity of 600ml¹. Check the oil level before each use and top up as the manual directs. The box contains the generator, adjustment tools and the user manual¹; no oil or fuel is listed, so both are bought separately.

Never run a petrol generator indoors, in a garage, in a shed or in any enclosed or partly enclosed space, even with the door open. The guide to generator safety covers carbon monoxide, fuel and electric shock in full, and carbon monoxide warning signs explains what to look for.

Size, weight and noise

The HY3750i weighs 26kg net¹. The distributor states that a conventional generator of similar output typically weighs around 45kg, which is the advantage inverter design buys¹. Machine Mart's guidance makes the same point in general terms, describing inverter generators as generally lighter and more compact than conventional generators². The packaged weight is 28.5kg, so allow for that when collecting one¹.

The assembled dimensions are 435 x 380 x 470mm (H x W x L)¹. It needs a level, firm surface outdoors, with space around it for air and exhaust, and a route for the lead back into the house that does not run through a doorway people use.

Noise is the other practical limit. The distributor gives 72 dBA at 7m, with a second figure of 66 dB(A) elsewhere on the same page; the two figures disagree¹. Either way it is a machine neighbours will hear, particularly in the evening. The guide to generator noise and neighbours covers timing and placement. Running it in blocks, as the absence of eco mode already encourages, limits the disturbance as well as the fuel.

Safety in use

The HY3750i produces a 230V supply from two 13A sockets¹. The guide to extension leads and overloading explains how to add up what is plugged in.

Keep the machine dry. Do not run it in rain without protection that still allows the exhaust and cooling air to escape, and never bring it inside to keep it dry. The guide to running a generator in the rain covers safe practice.

Store petrol only as the law and your insurer allow, in a suitable container, away from the house and never in a hallway or under a stairs. The guide to storing petrol at home sets out the limits.

Warranty, support and what comes in the box

The distributor gives the HY3750i a warranty of 3 years for home use, 1 year commercial and 90 days hire, with a maximum of 1,000 hours¹. The hours limit matters: the digital display shows running hours, so you can track your own use against it¹. Keep the proof of purchase, because the warranty runs from the original date of purchase.

Other makers structure their cover in comparable ways, which helps set expectations. Champion's domestic warranty runs to three years, with parts and labour in year one and parts only in years two and three, or 1,000 hours, whichever comes first⁶. That is Champion's term for its own machines, not Hyundai's, but it shows the shape of a typical generator warranty: a time limit and an hours limit, whichever arrives first.

The box contains the Hyundai inverter generator, adjustment tools and the user manual¹. Nothing else is listed. If you buy secondhand, ask for all three, and check the serial number with the distributor. The distributor's product page is the place to start for the manual, parts and warranty enquiries¹.

The digital display shows output voltage, frequency and running hours at a glance¹. Use it to confirm the machine is holding 230V and 50Hz before plugging in sensitive equipment, and to log hours. It is a readout, not a substitute for the manual.

Where the HY3750i fits among backup options

A petrol inverter generator like the HY3750i sits at one end of the backup spectrum: it makes its own power from fuel, so it can run for as long as you have petrol, but it needs outdoor siting, fuel storage and engine maintenance. A battery power station sits at the other: silent, indoor-safe and no fuel, but limited by its stored capacity and recharged from the mains or solar. The comparison of a power station or a petrol generator sets the two side by side, and the guide to inverter or open-frame generators explains the difference in construction and noise.

Within the petrol field, the HY3750i's 3000W continuous output puts it above the smallest inverter sets and below the larger ones. If you are sizing a machine from scratch, the guide to what size generator you need works through the load calculation. If you already own a HY3750i, the backup power section covers the wider planning: what to keep running, how to store the machine between outages, and how to check it before winter.

For households who want to keep a gas boiler running, a generator can do it only through a proper connection to the house wiring, never by an improvised lead; the guide to running a boiler in a power cut explains why. And for anyone weighing a secondhand HY3750i against a new machine of another make, the honest answer is that the HY3750i is a capable 3000W inverter set whose support depends on the distributor, and whose age and hours should be checked before you buy.