Robotic lawn mowers save a hell of a lot of time and effort, and can help to keep your garden looking great without you having to do a thing.
Most robot lawn mowers come with a wire which you place around the perimeter of your lawn to tell the mower where to stop. The wire also acts to orient the mower, and help it to find its way back home for charging.
Sounds like a good thing, right? It is, there’s nothing wrong with a perimeter wire, and in fact, even though we have heard of some robotic lawn mowers that work without perimeter wires, they have some limitations (see below).
The consensus among owners seems to be that in the long run, it’s best to stick with the perimeter wire – at least for now.
Why? That’s what we’re about to discuss. But first, a quick explanation of how a robotic lawn mower works.
How do Robotic Lawn Mowers Work?
Many robotic lawn mowers work in a similar way to robotic vacuum cleaners; you set them off to do a job, and they map the areas they’ve been, and being careful of objects and hazards, keep going until the job is finished.
Most robotic lawn mowers need to know the area they’re cutting in, and this means having some sort of perimeter set up, such as a wire. The wire acts as a virtual fence containing it to the area that needs to be mowed.
The wire starts at the charging base runs along the perimeter of the garden back to the charging base.
The charging base therefore has 2 main purposes; to charge the mower and to send a low voltage signal along the wire.
Typically the robot mower will not function outside the perimeter wire – if for some reason it finds itself outside the perimeter (a cut wire maybe?) the mower will stop.
It should be mentioned, by the way, that the wire we’re talking about is the wire which comes with the mower, not just any old wire.
As for how they work, technically, a robot lawn mower knows that it’s on grass, as opposed to pathway, thanks to the sensors on the underside which detect things like moisture and density.
Why a Perimeter Wire is a Good Idea
We were going to do a pros and cons list of perimeter wires vs. no perimeter wires, but in reality, the advantages of having a robotic lawn mower with an installed perimeter wire far outweigh any reasons not to have one.
The main reason why having a perimeter wire for your robotic lawn mower is a good idea, is all about safety. With a wired system, you know exactly where the mower is going to cut, and that it will not leave the bounded area and either destroy your flowerbeds, or roll into the street to be hit by a car.
Why do some people not want to use a robotic lawn mower with a perimeter wire?
A couple of reasons: first could be that they think it’s unsightly to have a wire running around the edge of the lawn (although perimeter wires can be buried if required). It does require some effort to setup the wire initially, but no where near as much time as you will save by having the robot mow your lawn. It’s possible that your wire might be damaged, leaving your robotic lawn mower with no idea of where its boundaries are – it would then end up directionless.
Another reason for not wanting a perimeter wire is simply the idea of progress.
If there’s a wireless option, then why stick with the wired option? Wireless is favored in almost every other area of technology, after all, so why not push for it in our robotic lawn mowers? The truth, is that we are pushing for it, but there are still only limited options for robotic lawn mowers without perimeter wires.
But My Garden is Fully Enclosed By a Fence – Do I still Need The Wire?
There are some robotic lawn mowers that Your House Garden know about that can be set to mow without a perimeter wire, as long as your garden is completely enclosed by a fence.
The other important requirement (other than the full fence) is that there are not any objects below 4 inches in height throughout your lawn.
Any areas such as garden beds, pools or mulch beds will need to have a solid 4 inch high border.
LawnBott recommends that even if you meet these requirements, to be 100% certain that your LawnBott functions as advertised, that you still setup the perimeter wire (or consider the LawnBott Spyder LB1200 – see section below).
But we guess if you meet the requirements, and were interested in one of the robotic lawn mowers specified below anyway, then it could not hurt to try the mower without the perimeter wire initially to see how it behaves.
Just don’t forget to go into the menu to set the option to “run without perimeter wire” first.
The robot lawn mowers that can operate in this capacity are listed below (click the links to read more about them and find the prices on Amazon):
LawnBott LB200EL+ – could not find this on Amazon, so check with lawnbott directly if you are interested.
Which Robot Lawn Mowers Do Not Need Perimeter Wires – What is the Catch?
The first viable robot lawn mower that does not need a perimeter wire to operate is the LawnBott Spyder LB1200.
For this mower to work on your lawn certain (quite strict) criteria need to be met (see below). Also the key downside of this mower is that it needs to be charged indoors (average working time is 4 hours and average charge time is 2-3 hours).
The key criteria for the LawnBott Spyder LB1200 to work on your lawn are:
- total lawn size should be smaller than 5500 sq. feet
- No slopes greater than 25 degrees
- No curbs with sharp drop offs
- Lawn edging or borders must be a minimum of 5.5 inches
- Anything level with the lawn you do not want to mow (flowers etc.) should be protected by a 10inch barrier (either dirt, concrete, rocks i.e. anything that is not living)
- The mower will not work effectively if you lawn is dormant, sparse or very dry. The LawnBott Spyder LB1200 works by sensing moisture in the grass, which then activates the blades – if the grass is very dry the blades will not be activated
Experimental Options: GPS and Wireless
You can control your heating and television from your smartphone, so it makes sense that eventually you’d be able to control your lawnmower, as well.
There have been tests conducted with GPS mowers, but none are commercially available, and the only wireless option we’re aware of right now, is the (potential) upcoming offering from SmartMow.
What about Solar-Powered?
It’s a great question, and you’d imagine that a lawn mower, being an outdoor device, would be perfect for solar power, but in fact none of the major manufacturers has come up with a viable option yet.
This likely has to do with the fact that the batteries required to run a robotic lawn mower can’t yet be sustained with solar energy (or even to help sustain the battery charge while it works). In other words: It’s just not worth it.
All in all, it’s still the case for now that wired perimeter robotic lawnmowers are the way to go, and we’re ok with that. It is nice to think that, at least for now, humans get to set the boundaries for our robot friends.
Recommended reading: Best Robot Lawn Mower Reviews