Picking a Robotic Mower

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MorpheusPA
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Picking a Robotic Mower

Post by MorpheusPA » August 2nd, 2021, 1:36 pm

Myrtle died after more than a decade of service. It was a good death. OK, it wasn't, but I'm going with the positive. Right now, I'm mowing it with a Toro, which is fine, but my time available is about to change.

So we're looking for a new robotic mower. I've been overestimating our lawn size a bit, mostly because it keeps shrinking due to the gardens increasing in size (2.5K and rising) and my setting it large to begin with. Call it 8,500 square feet.

We've narrowed it to two models:

Worx WR155--Capable of 1/2 Acre [21K square feet], 20V, 6 Ah battery). Batteries available at Home Depot (2 or 4 Ah versions), or can be ordered online or through Amazon. App gets pretty poor ratings, but they all do. Disc blade, lasts 2 months on 1/2 acre. Looks like I can sharpen it myself to last the whole season on 1/2 acre, or about 2 seasons on mine. Garage available. Onboard control pad. Can handle 20 degree (35%) slope (I have nothing worse than a five degree slope). Rain sensor.

Husqvarna 115H--Capable of 0.4 Acre [about 16K square feet], 2A battery. Specialty battery, more expensive and I couldn't find it easily. Can handle a 30% slope ('bout 17 degrees). Disc blade, same as the Worx. Garage available. Controllable through the app. Rain sensor.

Prices are practically identical.

Practical difference: That 2A battery on the Husqvarna means it'll have to run more often, recharge more often, and die three times faster, a problem I had with Myrtle's batteries (which, unfortunately, were lead-acid). If the battery replacement were one third the price, that wouldn't matter, but it isn't, it's about the same, and the battery management doesn't seem particularly intelligent (it doesn't do an 80-20 run because it simply can't). You'll get 300 to 500 full charges out of a lithium battery at full stroke and that's it.

Due to the battery difference (the Worx is seriously cheaper) and availability (Worx is everywhere) and the fact that we already have other Worx products (that impress us with their quality) and batteries (that we like) that could be popped into the mower if necessary for additional run time or in case of a battery death, we're leaning hard toward the Worx. While using our other batteries would mean killing a 2A or using our 2A batteries, it's a practical difference of knowing we're making the sacrifice rather than being forced into it. Battery replacement on the Worx is also a snap, and can be changed on the fly for multiple mows a day if you want, and the batteries charged safely in any Worx plug-in charger. Which we already have.

If anybody else has a good model they want to share, please feel free, or other considerations (like you got the Worx and don't like it for some reason). It's best to know before we do this...

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Re: Picking a Robotic Mower

Post by Masbustelo » August 4th, 2021, 6:17 am

How does one measure slope to determine the degree? Asking for a friend.

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Re: Picking a Robotic Mower

Post by ENVY23 » August 4th, 2021, 1:05 pm

I don’t know how they compare, but have you looked at the Stihl iMow robotic mowers?

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Re: Picking a Robotic Mower

Post by MorpheusPA » August 4th, 2021, 2:20 pm

Pull your lot plan from the city, it should be right on there. :-) Contouring should be on the thing with altitudes if the surveyor did their jobs right.

My north-south rise to run is 1 foot over 100 feet. East-west, it's closer to 3', with most of that in the swale, for a grand total of ten percent grade (five degrees or so) at maximum.

Barring that, just estimate it. Stand at the lowest point, eyeball or use a second person to measure the highest from where you're standing, and figure that vertical (A). Walk out the horizontal (B) or use a string and measure. That will give you A and B. With that, you can simply look up the degrees (alpha) of the grade, or calculate it:

alpha = arcsin(a / c)

Most things use percent of slope, but you can calculate that:

Degrees = arctan(slopepercent/100) [If you don't use the decimal point; if you do, just don't divide by 100]

Or, more simply, look it up: https://www.calcunation.com/calculator/ ... ersion.php

A 30% slope is just under 17 degrees (pretty steep), a 20% slope is 11 degrees. An almost-unnavigable 90% slope is still only 42 degrees. Slope percentages top at 45 degrees.

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Re: Picking a Robotic Mower

Post by edslawn » August 4th, 2021, 7:28 pm

I've also seen a simple method with your smartphone. Get a 2x4 with a little length to it, download the app "simple inclinometer" on your smartphone, set the board on the grade, and put your phone on top of the board. I haven't done it, but it seems pretty straightforward. It seems like you could do the same with two stakes and a string to longer hills.


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Re: Picking a Robotic Mower

Post by MorpheusPA » August 4th, 2021, 8:56 pm

What's a smartphone? Although I guess I'm shortly to find out...

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Re: Picking a Robotic Mower

Post by northeastlawn » August 5th, 2021, 6:28 am

Morph your just showing off

About a dozen ways to do it, here is the easiest non smart phone way.

Take two stakes place them 10’ apart; then get a string line with a string level, tie the string between the two stakes and get the string level with the string level. Measure the height between the ground and the string at both stakes. Take both numbers and subtract them, then divide by 10. That’s your slope.

Slope is just rise / run, it does even need to be 10’, but that just makes the numbers easier. As a former surveyor I would just pull out my iPhone, put it on a long 2x4 and open the level app But I got a kick out of having someone calculate there slope from the contours on a site plan, it’s been a long time since I have done that.

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Re: Picking a Robotic Mower

Post by MorpheusPA » August 25th, 2021, 7:25 pm

We went with the Worx WR155, which is due for delivery on Friday. I'll spend the weekend fixing that up.

Interestingly, my new Samsung Galaxy phone has an interesting feature where it can directly measure the angle of any surface it's put on. It's native on the A12, so it should be available on any more advanced model.

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Re: Picking a Robotic Mower

Post by edslawn » August 26th, 2021, 8:17 am

MorpheusPA wrote:
August 25th, 2021, 7:25 pm
We went with the Worx WR155, which is due for delivery on Friday. I'll spend the weekend fixing that up.

Interestingly, my new Samsung Galaxy phone has an interesting feature where it can directly measure the angle of any surface it's put on. It's native on the A12, so it should be available on any more advanced model.
Looks like a nice little rig! Be sure to post updates and videos.

On a related note, I have robot vacuums on each floor of my house and love them. We have dogs and the robots help inbetween the human vacuuming.

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Re: Picking a Robotic Mower

Post by MorpheusPA » August 26th, 2021, 6:49 pm

One day remaining. I've already adjusted my schedule at work for 7:00 AM to 3:30 PM with the boss' blessing, so I'll zip home and start installing. I'll hopefully finish on Saturday.

I already downloaded the app, and I'm already stressing my A12--and already thinking I should have simply bitten the bullet and gotten the S21+ Ultra. Because the cellphone's camera is twice as good as my Canon. The S21 is about eight times as good as that.

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Re: Picking a Robotic Mower

Post by MorpheusPA » August 28th, 2021, 10:38 am

It arrived yesterday. I got home before 4 PM (my schedule currently being 7 to 3:30), opened it up, and started installation (I'd already reviewed the instructions online, made a ruler for myself even though one was in the box, and knew what to do). I cut the perimeter where the wire will go short so I can get the wire into the grass easily.

Then worked until it was too dark to see. The result being about seventy mosquito bites on my hands and 150 feet of the perimeter done. But I did the hardest part first, the curve around the gardens and an island around a tree.

Just shoot me. :-) There's about 450 feet to go, including an isolated zonal island of the Thuja. It's a close thing as to whether I run out of wire, but I still have plenty of Myrtle's wire left over, which will work just fine.

This mower has the entire lawn as one huge zone, so setup is a no-brainer unless you have an island to exempt which is larger than 36' by 36' that isn't something like your house. Which I do--the line of Thuja. Then you just have to ring it out with a zone barrier at some point around it where the line in the middle of the barrier to the property edge (about 2") might not get mowed. I'm hiding that behind the rose bush and I'll do it with the weed whacker if that happens. The WW is also a Worx and runs on another lithium battery by them. :-)

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Re: Picking a Robotic Mower

Post by edslawn » August 28th, 2021, 6:08 pm

Sounds great... can't wait to hear how it works

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Re: Picking a Robotic Mower

Post by MorpheusPA » August 28th, 2021, 8:16 pm

I ran out of wire. Turns out I did have lots of wire left, but I'm about sixty feet short. So I ordered more. It should be here mid-week. Since I need wire, I ordered more pegs as well and went heavy on pegging down the wire to avoid trip hazards on the perimeter.

From 11 AM to 5, I ringed the property. So from the 150' point to about foot 750. I underestimated a bit--I have a bit over 800 feet of perimeter once the Thuja are included. So nine hours total so far, with around 2 to go. Figure once you get into the swing of things, a hundred feet an hour isn't a problem. Faster if you rush it and have extra pegs. I don't suggest rushing.

But I also installed the (optional) garage for the robot, which was a snap. It says it's easy enough for a child to install. I went looking for a child. I found my husband instead, who was quite helpful.

The cell phone even came in handy. I had it playing Stradella, then Mozart, then a bit of Haydn as I got tired and my ability to pay attention to anything complicated started to fade.

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Re: Picking a Robotic Mower

Post by MorpheusPA » September 2nd, 2021, 8:26 pm

The new wire got here, I finished installation, and lit him up.

https://vimeo.com/manage/videos/596879999

If you note, the sound of the crickets is louder than the mower, which I'm standing directly over. It ran for about 2.5 hours on its first charge, complicated by the fact that I need to adjust the front line (it got stuck three times and alerted me through the app) and skidded a bit (the soil is absolutely soaked from Ida).

I'll finish adjustments tomorrow, which should be less than an hour. The programmed mowing cycle is already in, daily except for Wednesday and Thursday, which just fell out that way.

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Re: Picking a Robotic Mower

Post by edslawn » September 2nd, 2021, 8:49 pm

Very cool! I'm sure you will get it dialed in.

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Re: Picking a Robotic Mower

Post by Masbustelo » September 3rd, 2021, 1:52 pm

Nice video. I totally like the concept.

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Re: Picking a Robotic Mower

Post by MorpheusPA » September 3rd, 2021, 6:40 pm

I moved the front wire back a bit (the Township reworked our front line and borked it completely, dropping it such that the curb is 3" above the ground. Otis, which won the final name contest, was getting stuck).

He's out mowing now. Undoubtedly there will be minor adjustments with the wire, probably out front again where the pitch is awful and slides right into that curb line, but I'll work with that as needed.

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Re: Picking a Robotic Mower

Post by RTM » September 4th, 2021, 3:56 pm

There is a new kid on the block - the segway navimow. It uses gps vs wires for boundaries. Looks like it handles slopes up to 40 degree. However, max height for a cut is a mere 6 inches.

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Re: Picking a Robotic Mower

Post by MorpheusPA » September 5th, 2021, 11:36 am

"The Navimow H500E is for lawns with an area of up to 5,400 square feet and will cost around $1,400, which certainly isn’t cheap."

They seem to be on the more expensive side and don't have a release date or firm pricing just yet. The comparable Worx model is $999. I actually like the wire--this morning, Otis slid outside of it in the dew and warned me immediately via the app. It told me what I already knew--I have to repair that front line I've been needing to repair for the last nine years.

So I did that. In the rain, of course, but that meant Otis had already gone back home to sit and rest and experience a rain delay.

Image

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Re: Picking a Robotic Mower

Post by RTM » September 7th, 2021, 12:14 pm

Yes, definitely, the navimow is pricey.

Just wanted to correct something that I wrote that was based on news articles. The Nanimow can handle a 45% slope (24ish degrees, NOT 40 degrees as I read in an article).
RTM wrote:
September 4th, 2021, 3:56 pm
There is a new kid on the block - the segway navimow. It uses gps vs wires for boundaries. Looks like it handles slopes up to 40 degree. However, max height for a cut is a mere 6 inches.
Morph, glad your happy with your Worx. RIP Myrtle.

I am in the market for the first time, but getting my feet wet right now and I appreciated your DD above. I will not get the Navimow primarily due to the max cut height.

In addition to the Worx, I am considering the Greenworks Optimow 50 High Robotic Lawn Mower (1/2 acre, 4 inch highest cut, 4.0 Ah Battery, rain sensor, 35% slope, comes with a "garage," but it clocks in at $1,599.99 USD). Not in a hurry. Going to look for sales going into Winter up north.

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