Hyundai HY40CLM38 38cm / 15" 40V (2x20V) Cordless Lawnmower Review

1. Introduction - Where This Mower Fits in Hyundai's Range

If you've already looked at Hyundai's smaller HY20CLM33 - which I reviewed separately here - you'll know that Hyundai's CLM cordless range takes a different approach from their older petrol-focused HYM series. The CLM models are designed around brushless motors and dedicated battery systems, with a focus on practicality and value rather than premium aesthetics.

The HY40CLM38 sits a clear step above the HY20CLM33: a bigger 38cm cutting deck, a combined 40V system using two 20V batteries, a larger 36L grass bag, and a longer advertised runtime. At approximately £229.99, it occupies a competitive part of the market - above the basic beginner cordless bracket but well below the premium EGO or Husqvarna territory.

The question I wanted to answer in this review was specific: does the HY40CLM38 justify the jump from its smaller sibling, and is it genuinely capable of replacing a petrol mower for a medium-sized UK garden? Having tested both machines across multiple mowing sessions - in spring growth, after a week of rain, and during a dry spel, the answer is mostly yes. With some important caveats.

2. Full Specifications

 Hyundai HY40CLM38 38cm / 15" 40V (2x20V) Cordless Lawnmower Review

3. Motor, Power and the 40V Dual-Battery System

The brushless motor is the headline feature here, and it genuinely matters. Brushless motors run more efficiently than their brushed counterparts, generate less heat, and have a longer operational lifespan - considerably less wear over thousands of mowing hours compared to a brushed equivalent at this price point.

In practice, the 40V combined output gives the HY40CLM38 noticeably more grunt than the single 20V HY20CLM33. On established, dry turf cut to around 35mm, the machine moves through grass smoothly and confidently. Blade speed feels consistent; the motor doesn't labour noticeably until you push into genuinely thick or wet material.

Spring growth after a rainy week is where this mower gets a real test. On a mixed fine and coarse-bladed sward of around 200m², the mower managed without bogging down on lush spring grass at the 35mm cutting height. On the lower 25mm setting with dense turf, you notice the motor working harder and runtime shortens noticeably. This is true of most cordless mowers at this voltage,  it is not a criticism unique to the HY40CLM38, but worth factoring in if you are dealing with consistently dense or damp grass.

4. Runtime - The Honest Picture

Hyundai advertise up to 50 minutes. In real-world conditions on a medium-density lawn at a sensible cutting height of 35–45mm, real-world runtime of around 35–45 minutes was achieved before the battery indicator entered the red zone. That is honest enough for a mower in this class, and the advertised 50-minute figure is achievable in optimal dry conditions with well-maintained, shorter grass.

The key advantage of the dual-battery setup is that both batteries charge independently. Rather than waiting for one large battery to reach full charge, you can stagger the charging - or keep a spare pair charged if you are mowing multiple areas. For a garden of 200–250m², 40 minutes of real-world runtime at 38cm width should be enough to complete the job in a single pass.

5. Cutting Performance and Height Adjustment

The 38cm deck with five height positions spanning 25–65mm gives a practical range for UK conditions. The 25mm minimum produces a tight, even cut suitable for a decorative lawn in summer. The 65mm top setting is useful for a high rough-cut on overgrown areas or when you want to take as little off the top as possible during drought conditions.

Cut quality is clean. Grass collection efficiency into the 36L bag is good at normal heights — the airflow design pulls clippings through effectively, and the bag fills more slowly than its modest capacity might suggest. On longer, damper grass, the mulching mode (bag removed, mulch plug engaged) works well enough, though fine-chopped clippings can accumulate visibly if you push through really heavy material.

Rear discharge is available as a third option  useful for a quick rough-cut on an overgrown patch where collection is not the priority. Switching between modes took under 60 seconds in testing.

One genuine limitation on cutting close to edges: the double-wall plastic deck design means the blade does not extend quite to the very edge of the deck housing. This is common with polypropylene decks and leaves a small strip near walls and borders that will need finishing with a line trimmer - a minor but real additional step in the mowing routine.

6. Noise Level and Ease of Use

One of the standout practical benefits of a brushless cordless mower in this class is the noise output — or more precisely the lack of it. At typical operating distance, the HY40CLM38 is genuinely quiet, comfortably under 85 dB in normal use and well below the 95–100 dB output of a comparable petrol rotary. You can hold a normal conversation while mowing, which is not something you can say about a 139cc petrol machine.

For those with noise-sensitive neighbours, gardens in built-up areas, or a preference for early weekend mowing without guilt, this is a genuine and practical advantage rather than a marketing point.

Setup straight out of the box is minimal, fold out the handles, insert both batteries, fit the grass bag. No tools required, and assembly takes under ten minutes. Starting is a two-step process: insert the safety key, then squeeze the handle bail. It is intuitive, safe, and considerably more pleasant than yanking a pull-cord on a cold petrol engine in March.

Weight is approximately 14–15kg with both batteries fitted, which makes this noticeably heavier than the HY20CLM33 at 10.28kg. For most adults this is manageable for a 30–40 minute session. However, if you are mowing a sloping garden or need to carry the machine up steps to reach a raised lawn, the additional weight is tangible. There is no self-propulsion, it is a push mower, so on inclines you will feel that mass. On flat ground, manoeuvrability is good and the machine turns efficiently at headlands.

7. Build Quality and the Plastic Deck — An Honest Assessment

The machine's deck is polypropylene rather than steel, which is the main structural conversation point. Polypropylene decks have improved considerably over the last decade - they do not rust, they are lighter, and a quality moulding can last many seasons with normal use. Hyundai's moulding here feels solid; there is no flex or creaking in normal operation.

That said, a polypropylene deck will not survive an encounter with a buried stone or concrete edge the way a steel deck would. If your garden has hidden obstacles, rough terrain edges, or you are inclined to clip paving kerbs, a steel-decked machine would be a wiser long-term investment.

The handle feels sturdy and folds down cleanly for storage. The height adjustment lever moves through its five positions with a satisfying click. The grass bag clips on and off without tools in a few seconds, which matters during a session when the bag needs emptying mid-lawn. The folded footprint is compact enough for most garden sheds.

8. HY40CLM38 vs HY20CLM33 — Is the Step-Up Worth It?

Having spent time with both machines, the step-up is clear in some areas and less meaningful in others. Here is how they compare directly:

The HY20CLM33 is a genuinely capable machine for smaller gardens, see our full review here. It is lighter, cheaper, and easier to store. If your lawn is under 150m², the smaller model will serve you well and saves you £90.

The HY40CLM38 earns its price premium on gardens from 150m² upwards, primarily through the wider deck and the longer runtime from the dual battery setup. The extra 5cm of cutting width sounds minor but on a rectangular lawn can reduce mowing passes by 10–15%, which adds up meaningfully. For a 250m² garden, the HY20CLM33 might complete the job but at the limit of its battery,  the HY40CLM38 has genuine headroom. The trade-off is the heavier weight, which is noticeable for older users or those carrying the machine over steps.

9. Who Should Buy the HY40CLM38?

10. Pros & Cons

11. How It Compares — Competitor Analysis

vs Greenworks GD40LM35K2X (~£179–£199)

Greenworks are one of the strongest competitors in the 40V cordless space. Their dual-battery 35cm model is slightly narrower than the Hyundai and comes with smaller 2.0Ah batteries — meaning significantly less total runtime. The Greenworks build quality is solid and UK support is established, but the Hyundai wins on raw battery capacity: 2 × 4.0Ah versus 2 × 2.0Ah is a real-world mowing time difference that matters on a 200m²+ garden.

vs EGO LM1701E (~£349–£399)

The EGO is the premium benchmark at this deck size. It is a 56V machine with a wider 42cm deck, better overall build quality, and more power — but at roughly £120–£170 more than the HY40CLM38. If you have a large garden and want a long-term investment, the EGO is genuinely superior. For a 200m² domestic lawn on a sensible budget, the Hyundai is the more proportionate choice and the specification gap does not justify the price difference for most users.

vs Makita DLM380 (~£280–£350 with batteries)

Makita's equivalent runs on two 18V LXT batteries and benefits from the vast Makita 18V ecosystem, if you already own Makita tools, battery interoperability adds real value. For those starting from scratch, the Hyundai undercuts Makita substantially on initial outlay and includes batteries in the box. The Makita's trump card is ecosystem breadth; the Hyundai's is purchase price and batteries-included value.

12. Maintenance and Running Costs

One of the practical advantages of a brushless cordless mower over a petrol equivalent is the near-zero maintenance requirement. No oil to check, no air filter to clean, no spark plug to replace, no fuel to stabilise before winter storage. Running costs are pence per session in electricity rather than the £5–10 per session in petrol and oil you would expect from a comparable petrol rotary.

13. Detailed Score Breakdown

15. Our Verdict

The Hyundai HY40CLM38 is a solid, practical cordless lawnmower that gets the fundamentals right: a brushless motor, meaningful battery capacity across its two 4.0Ah cells, a sensible 38cm cutting width, and three cutting modes from the box. For a homeowner with a medium-sized UK garden wanting to move away from petrol without spending £400 or more, it is a genuinely good option.

It is not without compromise. The plastic deck, absence of self-propulsion, the requirement for both batteries to be fitted, and a slightly modest bag capacity are genuine limitations rather than cosmetic concerns. But at approximately £230 with two batteries and a charger included, Hyundai are offering significantly better value than many brand-name alternatives at a similar price, particularly when compared to the Makita DLM380 which costs more and requires batteries to be purchased separately.

If your lawn is 150–300m², you mow on flat ground, and you are buying into cordless for the first time or upgrading from the smaller HY20CLM33, the HY40CLM38 deserves a serious look. Step up to EGO if your garden demands more. Drop down to the HY20CLM33 if your garden is compact and you want to save £90 and several kilograms of carry weight.

Review based on hands-on testing across multiple mowing sessions 2026 on a mixed fine and coarse-bladed sward of approximately 200m². Specifications confirmed from Hyundai Power Equipment documentation and B&Q product listing. Price ~£229.99 correct at B&Q at time of publication, May 2026. This review contains affiliate links - Garden-Review may earn a commission if you purchase through these links, at no extra cost to you. Our editorial opinions are always independent. Jim Fellows is a garden machinery specialist at Garden-Review with over 15 years of hands-on experience testing and reviewing outdoor power equipment across residential and professional settings.