Best wire-free robot mower

Every robot mower needs to know where the lawn ends. Until recently that meant a wire pegged or buried around the whole perimeter, installed once and repaired forever. One machine in our registry does it without the wire, and the difference is worth more than any spec on the box.

The short answer

What the wire actually costs

A boundary wire is not expensive to buy. It is expensive in the things that happen afterwards.

• Install day. The wire follows the entire perimeter, plus an island loop around every bed, tree and pond. On a complicated lawn that is a full day's work before the mower cuts anything.
• Every aeration. Core aeration punches 3 inch holes; a pegged wire at the lawn edge is directly in the way. So is edging a bed, and so is any digging.
• Every layout change. Move a bed, add a path, take out a tree, and the boundary has to be re-laid rather than redrawn.
• Faults. A break stops the machine, and finding it means walking the perimeter with a meter.

A wire-free machine replaces all of that with a phone. What it does not replace is coverage, which is where the honest comparison starts.

Wire-free against wired

1. Segway Navimow i105N — no wire, and a computable duty cycle

Segway publishes both halves of the cycle: 60 minutes of running against 90 minutes of charging. Almost nobody in this category publishes both, and it is what lets you work out how much cutting actually happens.

Add 24 lb — light enough to carry to a shed single-handed — and a published 58 dB(A), and this is a machine designed around a small lawn and a quiet neighborhood.

The limits are published and hard: an eighth of an acre, 7.1 inches of cut per pass, and 16 degrees of slope. Segway also publishes no minimum sky-view requirement for the RTK positioning, which is the one thing we would want to know before putting it under trees.

#ad Check the Segway Navimow i105N Robot Mower price on Amazon — how we're funded.

2. Husqvarna Automower 450XH — the wire buys you ten times the lawn

An acre and a quarter, 270 minutes of mowing per charge, a 9.45 inch cut and GPS theft tracking. The boundary wire is the price of that scale, and on a large open lawn it is a price worth paying — a wire laid once around a simple perimeter is not the ordeal it is on a lawn full of islands.

Note the second slope figure before committing: 45% inside the installation but only 15% where the wire runs. A perimeter that climbs a bank rules the machine out regardless of how flat the middle is.

#ad Check the Husqvarna Automower 450XH price on Amazon — how we're funded.

Which one your lawn is asking for

1. Small, complicated, and you change the beds often: wire-free. The app boundary is the whole advantage.
2. Large, open, and settled: wired. The wire is a one-day job and the coverage is ten times greater.
3. Heavily wooded: neither, until Segway publishes a sky-view requirement. Satellite positioning under a canopy is the open question.

Installation detail for both approaches is in our robot mower setup guide.

What we cannot tell you

We have not installed either machine. Segway publishes no sky-view or satellite requirement, no boundary slope limit and no working-area derating for complex layouts. Husqvarna publishes no charge time for the 450XH, so its duty cycle cannot be computed the way the Navimow's can, and no noise figure for either Automower. Neither maker publishes how many square feet a single charge cuts, which is the figure that would let these two be compared directly rather than by working area.