Cobra MX46S40V cordless lawn mower review

A cordless lawn mower that packs a punch – read our Cobra MX46S40V cordless lawn mower review

Cobra lawn mower review
(Image credit: Cobra)
Real Homes Verdict

Cobra’s top of the range cordless lawnmower is a serious piece of machinery that answers many of the concerns gardeners might have in moving to this new technology.

Reasons to buy
  • +


  • +

    Cuts evenly (and quickly)

  • +

    Long runtime thanks to its clever two-battery system

  • +

    Batteriesrel atively quick to recharge between cuts.

Reasons to avoid
  • -

    Heavy lawnmower which may not suit everyone

  • -

    Only necessary for a serious gardener

Why you can trust Real Homes Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Looking for an honest Cobra Lawn Mower review? Let’s face it, unless you’re a gardener of industrial scale, you won’t be looking for your second or third generation cordless lawn mower. By far the biggest market for the new cordless machines is in people upgrading (if that’s the right term – more of which in a minute) from either corded electric, petrol or, if you’re of a certain generation, push mowers.

This reviewer has tried a few cordless models out but is also transitioning from corded to cordless – and it’s worth saying from the off that the Cobra not only performed brilliantly but answered many of the concerns that those looking to swap technologies might have.

I tested the Cobra over several months, from regular late summer cutting to a recent, and much less enjoyable, first cut after winter (and about six months of no cuts at all). The Cobra was tested on our four lawns around our house, which vary in size and consist of subtly different issues, including heavily mossed lawns, softer soil types and, to use a distinctly unscientific term (but one that regular lawn mowers will understand) bounciness. The total lawn area is 675m².

For more reviews, as well as design ideas, head over to our garden ideas hub page.

Review summary

As a machine for making the transition to cordless technology seem easy - this is it. The Cobra was powerful, cut well and evenly (and quickly) and ran for ages on its clever two-battery system. Batteries were relatively quick to recharge between cuts.

A powerful machine which packs a significant punch, it has a wide cut width and could handle most of what our difficult lawn threw at it. It’s well-built and packed with features and, best of all, gave me the quickest and easiest cut I’ve ever had on these gardens. Everything from the additional cut width to the bigger basket and, of course, not having to worry about the cord all the time gave me the easiest lawn mowing experience I’ve had. It’s not the most easy to manipulate machine – a heavy lawnmower, it’s a serious solution fo the serious gardener.

Practicalities and features

Assembly from the box took around 30 minutes, and the Cobra is quick and intuitive to understand. There are three different grass gathering options, from the traditional (and easy to install/remove) rear basket to a couple of mulching outputs.

Handle height wasn’t the easiest to adjust, but the mower is pretty easy to get going and whilst not self-propelled does give an easy ride. There are seven easily adjustable cutting heights with – by some distance – the best quality adjusting handle I’ve used in 20 years of mowing lawns.

Battery life

The success of a cordless machine - and one so critical to the success of the weekend as a lawnmower – is the run time of the batteries. One of the main features of the Cobra is that it runs off two batteries so you’ll have loads of run time and in all but the biggest gardens have plenty of spare capacity.

The manufacturer claims that the Cobra is capable of 40 minutes of mowing on perfect lawn condition. On lawns that are more difficult than the standard we found the batteries lasted 75, but still ample time to complete 650m² of difficult lawn in just 35 minutes.

Cutting quality 

As regular lawn mowers will know, the key to a straightforward cut is not to cut too short. On a sensible setting of three (out of setting) our regular, weekly summer cuts were effective and fast – and helped to build strength in the grass itself.

The Cobra modulates its rotary cut speed based on the grass conditions and this works brilliantly almost all the time – our mower only cut out to any degree on the recent post-winter cut where, thanks to the excessively wet winter, we’ve had a lot of moss and the grass has become a lot more problematic.

Value for Money

The Cobra is an expensive piece of garden machinery and as such is positioned for owners of larger gardens for whom regular mowing with a corded or petrol mower is proving increasingly wearing.

It’s an investment rather than a quick solution for a single year but the pay off is clear – an easier cut, a quicker cut, and a machine that finally makes lawn mowing a straightforward and simpler task.

Corded vs cordless lawnmowers

Cordless technology has dominated the power tools market for years – and now it’s beginning to make sense for larger garden machines, too. Is it finally time to make the switch?

For anyone looking to invest in new garden machinery, the world has changed quite a bit in the last couple of years. Everywhere you look brands are launching cordless models - some, such as Karcher and Riobi, as a suite of different tools that share the same battery. But just because something is free of cable doesn’t necessarily make it free of trouble – so can cordless lawn mowers finally claim to be a viable solution?

The answer is – it depends what you buy, and it depends what type of lawn mowing action you’re into. The good news is that it is absolutely possible to buy a cordless lawn mower that can handle anything that a corded mower can and last long enough to mow even the largest lawns. And, of course, cordless mowers offer a range of additional benefits. So here are five home truths.

1. The tiny cordless mowers are good for very little...

If you’ve got a small, simple, flat lawn – perhaps no bigger than 25-40m² – you might just get away with finding the smaller cordless machines useful. For the most part, they don’t cut very well and the battery life is so poor that you might realistically get 20 minutes of cutting time off a single charge.

That said, they are extremely convenient, light and fast – the equivalent of running a vacuum cleaner on your lawn – but just don’t expect them to do very much.

2. Cordless can’t be beaten for convenience

Corded lawn mowing is a frustrating venture. Constantly repositioning the cable. Working out extension cords. Occasionally running over the cable. It slows things down and it’s a pain in the neck. With the right battery technology, cordless mowers give you a truly independent mowing experience and, thanks to the clean nature of batteries, there’s none of the mess involved in handling petrol engines.

3. You need to be organised

Clearly corded machines, with energy on tap, are not something that you need to plan ahead for. Cordless machines are different which means in practical terms that for those of us who mow on weekends we need to manage our batteries and charge them ready – because the recharge times are nowhere near the type of instant charge you might hope for.

4. The good ones are great

It’s a common myth that cordless technology is less powerful than corded. But generally speaking, with the additional power comes additional weight, which can make some of the top end, very powerful cordless machines quite heavy. For the most part this trade-off is worth it. The top of the range cordless mowers from the likes of Cobra are as good as any mower on the market for power, cutting quality and overall experience – and of course they come with the additional convenience of cordless.

5. So who is the perfect gardener to upgrade from corded to cordless?

Perhaps you’ve got a reasonably large size garden and your old corded mower has given you quite a few years of decent service. You don’t necessarily enjoy mowing the lawns and would rather save a lot of time on it yet still get good results. This is the sweet spot for a good quality cordless lawnmower buyer.

Looking for more gardening essentials?

Jason Orme
Jason Orme is the Editorial Director of and one of the UK's leading experts on renovation, extension and self build. He has built several homes for himself and advised 1,000s of others on the best ways to design and manage individual homes. He has worked with government to help shape housing policy, and is the author of The Self Build Dream.