Robot Lawn Mower Perimeter Wire Tips & Tricks

Based on the last few years of robotic lawn mower ownership, I have a number of trips, tricks and tools for setting up and maintaining my robot lawn mower perimeter wire, as well as some recommended products.

A key point to remember is that while some of these parts are compatible (pegs and connectors, for example) many of them are not. At the same time, for some of the more basic installation and maintenance tasks (extending the perimeter wire, for example) regular off-the-shelf third party components can be used.

Robot Lawn Mower Perimeter Wire Installation

The first tip is to be prepared to move the wire around after it has been installed. For this reason, I recommend laying the wire on top of the grass, rather than digging it in.

Figure 1 : Poor Return Wire Installation

My first attempt at laying the perimeter wire wasn't exactly a triumph (see Figure 1).

Our lawn mower is the excellent Husqvarna 105 / Flymo 1200 / Gardena R40Li, and I followed the instructions to the letter.

What I forgot, however, is that something the size of a robot mower doesn't easily pass through a gap in a fence.

In addition, the design of the mower actually gives you a way out -- in the form of the return wire (the blue line in Figure 1). How it works is this: the mower leaves the charging point (on the right) and mows the lawn at random.

When it runs out of power, it will look for the return wire, and follow it back to the charging station.

The trouble is, when installed as above, the mower will (a) rarely make it into the top-left, and (b) once it's there, it will run out of power looking for the return wire, which it almost never finds.

There are a few solutions to this. The simplest is to to carry the mower to the top-left, and then remembering to get if back again once it runs out of juice.

However, the saving grace comes from the mower's design.

Figure 2 : Better Return Wire Installation

Reading through the instructions it transpires that there is a way to get the robot to follow the return wire at the start of a mowing session.

This led to the solution in Figure 2. The black line shows the new location of the return wire, designed to help the mower find its way home.

At the same time, once set up correctly, the mower will, occasionally, start from the end of the return wire.

One last note: since I had already installed the blue wire, I didn't want to uninstall it, so I added a box that enables me to switch between the two. I'm cautious like that.

To achieve this, I used some kit from the following section.

Lawn Mower Perimeter Wire Maintenance

Although tough, perimeter wires can be broken. Especially if, like me, you've scrimped a bit and bought some lesser grade wire to extend the length of that which has been provided.

Figure 3: These are not the connectors you are looking for...

Here's a first hint: buy the wire that is recommended by the manufacturer. It's just better.

But, it's not indestructible, and so it helps to have a few bits of kit that can help you when the worst happens and someone cuts through it with a spade, or a rodent chews through it.

Or, more likely, one of the little terminal blocks that you used to connect two bits together fails.

These are not good connectors. They are not waterproof, and, over time, will fail you. In my case, it took about 18 months to 2 years before the first one failed. I've now replaced all of them.

The replacement connectors are hugely expensive. Luckily, I've found a place where you can get a selection of waterproof wire connectors for use on the perimeter wire, all very inexpensive.

My absolute favourite, though, is the damp-proof wire splice connector available through Amazon, pictured here in Figure 4.

Figure 4 : Better Wire Connectors

Firstly, they're not 100% waterproof, but I've found that this doesn't really affect them too much. Certainly not as much as a simple terminal connector.

They're also reasonably priced, and because you have to crimp them, they do hold better than some of the other solutions.

Finally, they're a 2-way and not a 3-way connector, so are less bulky when you have to partially bury them. The 3M ones that came with the mower tend to stick up and risk being sliced on the lowest blade setting.

With the connectors sorted out, there's just one item left: what happens when the lights go red?

Perimeter Wire Emergency Kit

The most common thing that happens is that one of the plugs at the back of the charging station pops out, breaks, fails, or otherwise needs replacing.

Figure 5 : Spade Connectors

Sometimes, it's enough just to push it back in. However, on occasion, they actually need to be replaced. Luckily, they're just spade connectors, and easily found on Amazon, for very little money.

In Figure 5, there's an example. For connecting to the Husqvarna / Flymo / Gardena base station, you'll only need the bit that crimps to the wire (perimeter / guide wire) and the other end 'plugs into' the base station.

However, these connectors also form part of my Perimeter Wire Emergency Kit, and can be used with any of the popular makes.

It's worth mentioning that any robot lawn mower with a perimeter wire needs a way for you to locate a break in the wire.

Typically, this requires connecting a 'flying wire' to the base unit (charging station) and then connecting it at various points around the perimeter wire to see where the break occurs.

But this is very troublesome if you need to go around breaking the wire and connecting a 3-way block to the perimeter wire before plugging in the flying wire. 

Figure 6 : Self Stripping Connector

Much easier is to use the self stripping connector type, as shown in Figure 6.

All you need to do with these is place them around the perimeter wire (with flying wire connected) and gently press the cover closed just enough to make the connection, but not enough to seal the connector.

If you press too far, don't panic, just leave it where it is.

These connectors are so cheap that you can afford to leave them in place -- and if you mark where they are, the next time you need to investigate a break, you just need to march up with your spade connector on the end of the flying lead, and plug it in!

One last tip: the flying wire need not be the best quality, but is must be long enough to run to the most distant point on your perimeter cable, as measured from the charging station.

So, those are the current robot lawn mower perimeter wire tips and tricks, from a few years of robotic lawn mower ownership. Feel free to add your own solutions in the comments below!

Gardena Robotic Lawn Mower Review

We have owned the Gardena R40Li robotic lawn mower since I started this blog, back in 2013. In fact, one of the reasons I started the blog was to share my experiences and decision process, and as such now feels like the time is right to write a full Gardena robotic lawn mower review, having lived with the beast for three seasons.

For those who don't have time to read the full review, here are the bullet points. First, the good:

• The grass has never looked better;
• I got time back to do railway modelling instead;
• The whole experience has been almost pain-free.

Now, the not-so-good:

• Yes, it was expensive;
• Yes, parts fail (if you don't take care of it);
• Yes, moving the perimeter wire can be a pain.

The conclusion -- I would buy it again, but I'd take better care of it (i.e. clean it properly) and set it up a bit differently, probably getting in an expert to do that with me. After all, they did offer a free consultation!

Gardena Robotic Lawn Mower Installation

Installing the mower looked so easy on the DVD that came with it that I decided to go it alone, despite the kind offer to have someone come and help me install the perimeter wire (for free). One Sunday afternoon, instead of actually mowing with the old petrol-fired behemoth that it was to replace, I got stuck into the installation process.

The R40Li comes with it's own charging station, which sits on a perimeter wire, which stops the robot going off and mowing the tulips and neighbours drive when it should be doing the lawn. There's also a kind of follow-me cable that hooks up the mid-point of the perimeter wire to the charging station.

The idea is that, if the robot runs out of juice, it can find the wire, and subsequently find its way home. This is a system that works very well, but also has a dual use, as the wire can also be followed to a hard-to-reach part of the garden in case the mower is in danger of missing it due to a narrow entrance.

This is, in fact, something I regret not having done. 

Instead, my return loop is just a straight line. Having connected everything up and left it there for three years, I'm wary of upsetting the apple cart by relocating it, and probably the professional installer would have spotted my error straight away!

Other than that, once everything was in place, pinned down with the black plastic pegs and connected with waterproof 3M connectors (all supplied in the box), and plugged into my outside plug socket -- note, this is indispensible -- the mower charged up and was put to work.

It does take an afternoon of hammering little pegs in, testing electric circuits, and crossing fingers on occasion, but you can do it on your own. Just try to think it through a little bit more than I did!

Operation of the Gardena Robotic Lawn Mower

The mower runs on a daily programme, which can be varied through the slightly confusing on-board menu system. Be prepared to keep the instructions to hand for the first few weeks, as you'll be fine-tuning things like the time of day the mower should operate, and the number of times it follows the cable to the end before starting a run rather than just setting off in a random direction from the base.

And, the mower is governed by randomness.

It sets off when its charged, but pretty randomly, in a random direction, and changes that direction by a random amount whenever it hits an obstacle, or reaches the boundary perimeter wire.

Repairing the perimeter wire is also part of the ongoing operation and maintenance of these kinds of robotic mower, and it is a bit of hassle. Here's a tip: make sure you keep a long piece of single-core wire handy for troubleshooting, and don't bury the wire intentionally; just let the grass grow over it, or cover it with thin paving stones that are absolutely level with respect to the lawn.

The reason for this is that fault finding requires connecting one end of the cable to the base unit, and then hooking the other end to various points on the perimeter until you get a green light.

After the first few times, it gets a lot easier; but for that first time -- make sure you have wire handy, as well as a knife to scrape a little plastic off the perimeter wire, a crocodile clip to connect the wire to the perimeter cable, and some electrical tape to fix it up after...

Parts that Failed on the Lawn Mower

The first item in this category -- blades -- isn't really failure. You need to change the blades every so often.

Tell tail signs that the blades need replacing are:

• Wobbling mower caused by uneven weight distribution (one might be broken);
• Unusual noise;
• Grass tips going brown (unevenly cut; more torn than cleanly cropped).

Luckily, removing them is child's play; but don't let a child near them because they're sharp! They just unscrew from the underside, and the packs of replacement blades come with new screws and full instructions.

Then, the wheels came off. Actually, that's not true. What happened was the rubber came off, and the wheels stopped gripping (this was after 3 seasons use, with no over-wintering). The replacements have a solid, moulded tread, so they'll last for the rest of the product's lifetime.

Also this year, the dampers broke. The rubber perished, and they stopped preventing the outer bumper from bashing against the collision detection system, as discussed here.

Other than these few points, which encourage me to take much better care of the mower (i.e. cleaning it and overwintering it properly), the last three seasons have been trouble-free.

Summary - Should You Buy a Gardena R40Li Robotic Lawn Mower?

Here's the thing -- I can't answer that, because I have no idea whether your lawn qualifies. However, if you hate following your mechanical mower around a pretty standard lawn, then I'd certainly consider it.

The Gardena R40Li Bumps Up Against A Problem...

So, having swapped out the rubber-tread wheels for nice, new shiny plastic ones (see: And Then, The Wheels Came Off!) the next bits that have failed are the two rear rubber dampers. These are going to need replacing, but first, let's take a moment to look at the symptoms and probable cause.

Before we do that, I'd encourage anyone that has the Gardena r40Li, Flymo 1200R or Husqvarna 305 to download the following exploded parts diagram from the Gardena web site:

• http://www.gardena.com/ddoc/GARI/GARI2012_AAaa/GARI2012_AAaa__R40Li.pdf

And, whilst you're perusing it, and probably going "Ah, that's what that bit is!" at the same time, remember that we've had the r40Li since 2013, and this is only the second repair that we've had to do. Yes, I've changed the blades a couple of times per season -- thanks to the kids, the grass is littered with twigs -- but this is only the second major bit of work I've had to do.

This is despite the fact that I'm not the best at cleaning, or winterising the robot mower, which is where I suspect the cause of the current problems lie.

The Odd Symptoms of Bumper Failure

On the face of it, I should have realised straight away that something was amiss.

The mower would stop, mid-mow, for no reason, and then reverse. Then, it would turn and head off  in a direction, before stopping again, reversing, turning and trying to get going in a number of different directions before giving up.

Having turned itself off, a restart listed a "collision detection failure" a few times, before I twigged that maybe this wasn't simply a question of the mower getting stuck in a corner.

So, I picked it up.

When I did so, grasping the cover, including bumpers -- look at the diagram, p.13 -- and the chassis listed alarmingly. Normally it bobs around, suspended, as I now know, on four rubber dampers, that give it flexibility and allow for the bumper to detect collisions.

Now, with one broken, it registers a permanent list to one side, and the inevitable bumper failure with it.

What Caused the Rubber to Perish?

Both the rear dampers have perished. Possible causes that spring to mind are:

• snails (and I'm not kidding: they eat the post!);
• cold (changes in temperature attacks rubber like nothing else);
• bumping into objects.

That last one is pertinent, as although the perimeter wire went in three years ago, we're still moving it around to get the best edge cutting possible. Thus, the mower spends a lot of time bumping into stone edges because the perimeter wire is just a little too close to the coping stones...

On the other hand, the amount of dead grass that I pulled out also hints that maybe that also had something to do with it.

Either way, my advice would be to:

• clean,
• winterise,
• avoid snails,
• place the perimeter wire a good distance away from any coping stones...

For readers with the same issue, the parts are numbers 574 46 91-02, and they cost around 7.50 EUR each plus delivery. Much less than the wheels; and I'll let you know how I get on swapping them out with the damaged ones.

The verdict? Still recommended!

Is This Just The Most Expensive Anti-Mole & Auto-Mulching Device Ever?

It's been a while (3 years) since I received the best time-saving gift ever, in my opinion.

Had I listened to the naysayers, my friends and colleagues included, I would have been gearing myself up for a life spent hunting for perimeter wire breaks, changing spinning blades, unclogging the mechanism, replacing batteries, fixing electrical shorts, etc. etc.

In fact, the Husqvarna (sold also under the Gardena and Flymo brands) robotic lawnmower that I have has required less corrective maintenance than the old walk behind Briggs & Stratton powered mower that I still haven't had the heart to throw away.

That mower had issues ranging from a continuous problem with the traction drive belt (it's a heavy thing, and having it pull itself was a very desirable feature!) to a blade that was nearly impossible to take off, sharpen, and once put back never spun evenly, threatening to tear the engine off the plastic chassis!

Next to these issues, replacing the wheels when one began to fall apart, and regular blade replacement fade into the background, and both tasks are extraordinarily easy to complete. No expensive over-wintering costs, either, or replacing the engine oil, or any other of the messy jobs that you usually associate with lawn mower ownership.

However; there are a few things that I've noticed in the last three years, and are worth pointing out.

No More Moles!

The first thing that comes to mind goes back to a comment to a comment that I made back in 2014: to do with rodents eating the wire. At the time, one of my readers had pointed out that his Honda robotic lawnmower was suffering because foxes were eating through the guide wire.

My answer was to bury it deeper, thereby protecting it from ground level interference, but not from moles, which I also assumed would find the wire from time to time.

How wrong can you be?

It turns out (and this is just anecdotal - if anyone can back it up I'd be interested to hear their stories) that the number of moles in the lawn area, as evidenced by the (lack of) molehills has dropped to pretty much zero.

We used to have an issue with moles, and in the past I'd even installed one of those mole stop devices which send a subterranean pulse to warn the little blighters off, but it broke and never got replaced. 

Needless to say, the moles came back.

With the robotic lawnmower installed, however, they seem to have gone away again. I know they're in the area, because the field has been attacked, as have the neighbours' lawns (albeit to a lesser extent than before), but within our perimeter wire -- nothing.

There's a couple of explanations I can think of:

• the irregular noise of the mower mowing creates vibrations (like the mole stop devices) that scare them away, or;
• the electric fields made by the perimeter wire and guide wire are keeping the moles at bay.

Either way, the lawn looks better for not having any mole hills, and being greener thanks to the continuous mulching that tales place thanks to the mower's regular operation and small cutting length.

The Grass is Greener on All Sides

Just a small note here, but we have noticed an improvement (and being smart after the fact I wish I'd taken photos!) in the quality of the lawns. They are greener and more lush, presumably down to the mulching.

My walk-behind mower actually had a mulching blade fitted because I'm pretty lazy and didn't want to have to (a) empty the grass box somewhere, and (b) dispose of the grass. So, I just let the blade spin, reduce the grass clippings to dust, and let them fall where they were.

However, for this to be effective you need to mow the lawn every few days in the summer; especially because, a bit like hair, if you cut it regularly and take care of it, a lawn tends to grow faster!

Did I mention that I was lazy?

I'll admit it: to the cynic, this sounds like an expensive anti-mole and auto-mulching device, but the net effect is a healthier lawn that looks great.

My next project is to fit a couple of cameras so you can see it in action: you might even get to see it scare off a cat!