The Robotic Lawn Mower Perimeter Wire Revisited...

Fitting a perimeter wire often requires breaking and re-connecting individual cables together; and when you buy a robotic lawn mower, they come with a selection of appropriate connectors. These, however, are quickly used up, and especially if the wire breaks (which it will do), leading to a hunt for replacement connectors.

Perimeter Wire & Guide Wire Breakage

For robot mowers that use perimeter wires, there are usually two ways that the wires are used:

• as a boundary for the work area;
• to guide the mower to the charging unit.

While any wire break is irritating, breaks in the boundary wire present more of a headache than the guide wire, as it involves investigating the whole loop. The instructions for the Gardena 40Li / Flymo 1200R show that there are three connection points on the base: two for the boundary wire and one for the guide wire.

There's also a light on the base (where the mower 'docks' -- you need to take it out to see the light) which has several states. States related to the boundary and guide wires are:

• Green -- all okay;
• Blue flashing -- break in the boundary wire;
• Yellow flashing -- break in the guide wire.

Fixing the guide wire is easy enough, as you can trace it fairly easily (I made a plan of my own installation!), and splice the wires together.

Splice Clips

To do this, I use a splice clip, pictured here on the right, which costs about 2.5 EUR for 20 (less than 4 GBP) delivered, from online retailer Banggood.

These might not be water protected like the 3M ones that came with my Gardena 40Li, but they do the job adequately, and are a lot better than the 'sugar cube' type blocks that I was using previously, which tended to rust.

These clips can also be used to repair the boundary wire, once you know where the break is!

The instructions for doing this can be a bit confusing, but the diagrams in the user guide are pretty self-explanatory. However, since they require plugging a flying wire into the base unit, and then using it to test ever-increasing sections of the perimeter wire, I found using a terminal and spade connector made things easier.

I found these on Banggood at the same time as the splice clips (click here), for less than £2 per pack of 5. One of the 'spades'can be attached to the end of the flying wire, of which the other end is plugged into the base, in place of the regular other end of the boundary wire.

Terminal/Spade Crimp Clips

The t-connection bits end up on the boundary wire -- there being no way to take them off -- but are useful each time there's an issue.

As long as you remember (or write down) where they are, you can troubleshoot that much more easily, as well as 'shorting' between two points if you want to limit your robotic mower for some reason.

To do that, all you need is a bit of wire, the right length, with a spade at each end, and two points on the perimeter wire with a t-connector between which to put the flying wire. Now, when the mower approaches it, it will treat the new wire as if it is the boundary wire.

Simple!

...And Then the Wheels Came Off!

It sounds like the punchline to a bad joke, but what do you do when the wheels come off your Gardena robotic lawnmower? The answer is simple, if a little long-winded: go back to the retailer and ask them to order new ones...

The Problem

The Gardena 40Li, Flymo 1200R, and Husqvarna 305 all look remarkably similar. In fact, I'd put money on the fact that they're all made by the same company, to the same design, which I'm fairly confident is Husqvarna itself.

To my knowledge, all of these share the same kind of wheels: a plastic hub and a rubber tread.

And here's the problem. After nearly 2 years of unbroken service (aside from over-wintering), my Gardena 40Li's wheels have come off.

Actually, it's just the rubber tread that has become worn out, and I found it lying on the damp lawn, with the poor mower comically pirouetting with one tread-less wheel being dragged around by the other, rubberised one.

The solution ought to have been simple -- in this day and age, surely it's possible to order Husqvarna parts online? Unfortunately, it proved to be a bit more tricky than I'd thought.

Out With the Old Wheels

Without the rubber tyres, not only can the mower not mow efficiently, but it also can't dock itself for charging, since the designers decided that the best way to achieve this would be to reverse the mowers onto the outdoor charging stand.

This means that they have to spin around (always turning the same way) and by coincidence, it looks rather as if it's the outside wheel that has come off worse and eventually failed.

So, repair is out of the question. De-rubbering the wheels is out of the question. Perhaps there's a DIY solution (let me know in the comments thread!) but the most obvious option is to replace the rubber treads.

In With the New Wheels

However, it seems that someone on the design team has realised their error with the wheels, and rubber treads aren't available, but nice, shiny, moulded plastic (with treads) wheels are.

They cost me around 25 EUR from the dealer, for a pair, and took a while to arrive -- they were permanently out of stock at the central stockists -- but when they did, they proved easy to remove and replace.

If you look at yours, you'll see that there are three torque type screws to remove, per wheel, which can be a bit tricky, due to the angles, but it can be achieved without dismantling the mower itself. This may not be the case for the original Husqvarna 305, but the Flymo 1200R and Gardena 40Li succumb to the direct approach easily!

The new wheels came without screws or washers, so you'll want to keep those and not throw them away when you dismantle the old wheels.

Besides the blades, and the occasional accident with the perimeter wire, this is the first 'major' part of the mower I've had to replace in 2 years, which makes it an immediate improvement over the old Wolf Garden manual motor-mower I used before, which suffered wheel-failure (traction belt) in the first year, and needed to be annually maintained by the local dealer to keep it working properly!

The next thing I expect to go will be the battery; I'm not sure what the lifespan of these is supposed to be, but we've already noticed extending charge cycles, and diminishing mowing times. Of course, without an actual measurement/download facility, that's anecdotal, but to be expected.

Still, being able to change the wheels myself, and as easily as changing the blades (despite having to shop-order them) removes another of my initial concerns about owning a robotic mower.