Robotic Lawn Mowers Full Story

Except for the new LawnBott 1200 Spider (*est. $1,400), robotic mowers require extensive initial setup -- laying wire around the areas to be mowed -- which can take several hours or up to a full day. Reviews suggest placing the perimeter wires somewhat tentatively at first, taking some time to experiment with the best placement. Several reviews note that the initial kits seldom include enough wire and pegs, but you can substitute regular 14-gauge THHN wire and even use large bobby pins for inexpensive pegs.

Reviews say that all the robotic mowers on the market do a pretty good job of mowing the lawn (though as with all mowers, you'll still need to trim the edges), so the main factors to consider in choosing a model are the size of your lawn and its maximum slope - as well as how much you're willing to pay for extra convenience. It's important to note that the maximum lawn area specified for each robotic lawn mower is the total area it can maintain all season, not just the area it can cut in one session or day.

Another consideration is your type of grass and how short you can cut it without exposing it to heat damage from the sun. The maximum cutting height varies among robotic mower models from as high as 3.25 inches for the Robomower RL850 (*Est. $1,800) and RL1000 (*Est. $2,000) - fine for most grass -- to as low as 2.36 inches for the Husqvarna Automower models - suitable only for fine thin grass in cool moist areas.. If you live in a hot area, experts say you really don't want to cut your lawn shorter than 3.25 inches to avoid sun damage to the grass.

Sound level can also be an important consideration. The LawnBott robotic mowers are quietest; reviews say they won't bother neighbors even if you mow in the evening or at night. Husqvarna mowers are nearly as quiet, but Friendly Robotics mowers are relatively loud. They're still not as loud as a gas mower, but if noise level matters to you, reviews say they're not your best choice.

Since you don't have to stay with the mower, its speed might not be a big deal, but because some robotic mowers are narrower than others, they take a longer time to cut the whole yard. Most robotic mowers are about 19.5 to 20.5 inches wide. Wider lawn mowers, such as the 26-inch Robomower RL1000, cover area fast but if your lawn has some narrow areas, they may not be able to fit. Both the LawnBott LB2100 Professional and the LB3200 Evolution are only 16.5 inches wide - a better choice for yards with lots of narrow spaces. As with all lawn mowers, you'll still have some trimming to do.

Robotic mower models

The Israeli company Friendly Robotics makes the robotic lawn mowers that are the most popular in the United States, and they have good safety features. Both the Friendly Robotics Robomower RL850 (*Est. $1,800) and RL1000 (*Est. $2,000) have been on the market for over four years, and have accumulated reasonably positive reviews from editors and owners. There's no reason to expect less from the new lighter, less expensive 2008 models, which add an alarm to the anti-theft security system. However, the new models are powered by motors with only about a third as much power as the RL850 and RL1000, and are meant to handle much smaller lawns.

The latest Robomower RM200 (*Est. $1,400) is the most basic entry-level robotic lawn mower currently available. It's designed to maintain very small yards up to 2,700 sq. ft. in size. You charge it indoors by plugging it into an outlet, and then carry the 39-pound mower to the starting point of the perimeter wire you've laid out. An optional remote control (*est. $70) lets you 'drive' it to the starting point rather than carrying it. This robotic mower incorporates a rain sensor, so it comes in out of the rain on its own (both to protect the grass, which shouldn't be mowed when wet, and to minimize the chances that it will bog down in wet ground). The mower itself, like all robotic mowers, is weatherproof. This model can handle slopes of up to 18 degrees.

The next step up, the Robomower RM400 (*Est. $1,800) , can mow up to 4,300 sq. ft. and comes with a charging station. It can be programmed to leave the station and do its job, then return - without any lifting or remote-control guidance. If your lawn has narrow areas of less than six-feet wide, however, you'll need to guide the robotic mower using the optional remote control. The mower is weatherproof but the charging station isn't, so it must be located in a dry place.

The older Robomower RL850 (*Est. $1,800) , like the RM200, plugs into an outlet and needs manual guidance at the start and end of its mowing session. It lacks a rain sensor, and of the three robotic mowers, is the one most apt to get stuck. It still gets top ranking in owner-written reviews at Amazon.com, however, probably because it's been available longer. The RL850 has knobby wheels for traction and can handle a lawn up to 10,700 sq. ft. - about a fourth of an acre -- but can only manage slopes of up to 15 degrees.

The Robomower RL1000 (*Est. $2,000) is the priciest Friendly Robotics mower, handling up to 17,200 sq. ft. (more than a third of an acre). This robotic mower comes with a charging station and, like the smaller, less powerful RM400, can be programmed to mow on a schedule. It leaves its charger without your guidance, does its mowing and returns to the charger. If you have defined more than a single area to mow, however, you'll need to guide it to the extra areas to get it started. Like the other Friendly Robotics mowers, it can also need manual guidance (by remote control) in areas narrower than 5.5 feet. It's best for flatter yards since it can only handle slopes of up to 15 degrees.

The Robomower RL1000 is now equipped with a rain sensor. Several owners reviewing earlier versions complain about the RL1000 getting stuck in wet ground, so the rain sensor should be a significant improvement. We also found quite a few complaints about difficulty keeping the lead-acid batteries in good shape over the off-season. Otherwise, reviews are quite positive about this model, which is the most popular robotic mower in the United States.

LawnBott robotic mowers, made by the Italian company Zucchetti Ambrogio, are the quietest robotic mowers available. They use more sophisticated technology and continue to develop high-end features; internet software updates are free. All the LawnBott mowers work without any manual assistance and automatically return to their base station whenever they need recharging. Then when recharged, they go back out to finish the work.

The LawnBott transmitter is very specific so it's much less apt than the Robomowers to get confused by other wireless devices. The LawnBott mowers can detect the difference between grass and air, so they automatically lower blade speed when traveling across a paved area or an area where the grass has already been cut. This conserves battery power and lets them cover larger areas. When a LawnBott robotic mower encounters heavy grass that's harder to cut, it automatically changes its mowing pattern into a tight spiral, mowing harder till the resistance lessens.

The entry-level model, the LawnBott LB2100 Professional (*est. $1,950) is the robotic mower that reviewer Kerry Clabaugh of Bamabots.com identifies as the most cost-effective choice over a seven-year period - at a savings of about $250 a year compared with the Friendly Robotics RL1000. His figures take into account ordinary maintenance costs (like new blades) as well as estimated repairs. Based on years of experience as a retailer, he also picks the LawnBott LB2100 Professional as the model with the best repair record.

The LB2100 is the only LawnBott that uses lead-acid batteries rather than more environmentally-friendly lithium-ion batteries, and it handles only slopes up to 12 degrees. You can upgrade to lithium-ion batteries (*est. $300), which halves the weight and enables this model to handle slopes up to 27 degrees. Even with the standard batteries, the LB2100 weighs only half as much as the Robomower RL1000 and costs less, yet can handle nearly twice as large a lawn - about three-fourths of an acre. You can program it to handle three separate areas, first mowing one, then recharging itself, then mowing the next, etc.

The LawnBott LB3200 (*Est. $2,500) comes with spiked wheels. It's lighter since it uses lithium-ion batteries as the standard, and doesn't depend on you to do the programming. Instead, you tell it the results you want - the height at which you want to keep the grass - and it continually reprograms itself to achieve those results. It not only times its mowing schedule to keep the grass as you prefer, but changes its mowing pattern to a tight spiral when it encounters a tough patch. You can almost double its range to 1.25 acres by adding another lithium-ion battery (*est. $300) or by buying it with two batteries to start with, as the LawnBott LB3200 Plus (*est. $2,750). Both are appropriate for hillier lawns of up to 27 degrees.

In one review, the LawnBott LB3200 is deemed dangerous because the blades take several seconds to stop when someone lifts it up at an angle. At the time of our report, we didn't find any comments in forums that agreed with this criticism, since robotic mowers have an excellent safety record and are designed to be operated from a distance. Anytime a LawnBott mower bumps into anything, it backs off immediately and changes direction.

However, as noted earlier, LawnBott and Zuchetti are working with the Consumer Product Safety Commission to add extra safety features to the LB3200 and the LB2100. A software-programmed magnetic switch shuts off the blades if the mower tilts rapidly or to a certain angle. In addition, a blade guard will prevent injury even if the user manages to run over a foot. The blade guard is shaped like a bowl so it also increases the mowers' mulching power. The handle used to lift the mower will be touch-sensitive so it shuts off the blades as soon as someone touches it.

This touch-sensitive handle is already designed into the newer top-of-the-line LawnBott LB3500 (*est. $3,250). The model has already been approved by the CPSC. According to Kerry Claybaugh, the LawnBott LB3500 has 360-degree bumper sensors that can tell the difference between animate and inanimate objects - so it backs away from a tree or fence, but shuts off its blades when it bumps into an animal or person.

The LB3500 robotic mower can handle lawns as big as 38,000 square feet and slopes of up to 30 degrees. You can add two more lithium-ion batteries to extend the range still further, or choose the four-battery Super LB3500 (*est. $3,840), which can mow at least two acres. LawnBott even makes a fifth battery for the LB3500 to extend the area to three acres. You can set any version of the LB3500 to mow four separate areas, all on its own. It can handle slopes up to 30 degrees, partly because it comes with extra-wide tires, but the Bamabots.com review says traction isn't ideal without the optional spiked wheels (*est. $60).