40V Cordless 20" Lawn Mower w/ 4.0 Ah Battery

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20-Inch Cordless Twin Force Lawn Mower is rated 4.4 out of 5 by 71.
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  • Includes one 40V 4.0 Ah battery, 2.0 Ah battery and charger
  • 3 Year Limited Tool & Battery Warranty

Perfect for yards up to 1/2 acre, Greenworks 40V tools are lightweight, start instantly, and require virtually no maintenance – no gas, no oil, no mess – but still deliver gas-like power.

  • Innovative Smart Cut™ technology automatically increases the speed of the blade when more power is needed
  • Dual blades offer better cut quality, superior mulching and bagging capabilities
  • Hassle free push button start
  • 20" cutting deck
  • 5 position single lever height adjustment allows for a cutting height range of 1-3/4" to 3-3/8"
  • 2-in-1 capability allows you to mulch or rear bag
  • Hard top rear bag indicates when the bag is full and needs to be emptied
  • Includes one 40V 4.0 Ah battery, 2.0 Ah battery and charger
  • 3 Year Limited Tool & Battery Warranty
Rated 5 out of 5 by from Superb, lightweight and very convenient I bought the G-Max 40V Twin Force 20-Inch Cordless Lawn Mower in February. Fortunately (for me), my wife loves yard work and I bought the mower for her. Of course, I volunteer to help. She was absolutely certain she wanted a self propelled, gas-powered mower. After reading dozens of reviews on the G-Max 40V telling us how lightweight it is etc, etc. I convinced her to try it. We are both extremely happy with the purchase. It is really very light. The easiest handling mower we have ever had. This led us to purchase more G-Max tools - blower, hedge-trimmer and edger. Adding a couple batteries means we are always ready to go. Thanks for a great product.
Date published: 2017-05-27
Rated 5 out of 5 by from 4 Year Warranty HONORED! I bought this mower online through Amazon Prime: April 30, 2017! Worked flawlessly up until Sept. 7, 2029 when the #2 Motor burnt out! Contacted Customer Service! They wanted me to take it to a service center for repair 40 miles from my home? After an hour of back and forth my rep. Kathrine announced that Greenworks was to send me a bran new unit by mail! I am to ‘box-up’ the old unit and Greenworks will send a Courier to my home to retrieve it! To me, this is 100% HONORING their product warranty and the HIGHEST form of CUSTOMER Satisfaction one could possibly hope for! Thank you GreenWorks! You are a testament to what a company should be! BRAVO
Date published: 2019-09-11
Rated 1 out of 5 by from Barely strong enough to handle a moderately yard 1 year of awful mowing. Dont bother attempting to mow if it has rained within the past 4 days and hasn't been hot and sunny since then. (Unless bagging) the shrouds don't have a proper discharge port so the clippings get caked up in the shroud - until you stop, scoop out the clippings, make a few passes and repeat. It only took about 3 months before it started whirring loudly, constantly going into the boost mode and batteries went from 1x 4ah battery being able to handle my yard to now requiring 1x 4ah, 1 2ah and my 2.5ah. Stays out of the elements and stored in a workshop. Don't bother.
Date published: 2018-08-14
Rated 5 out of 5 by from It just works! I own multiple Greenworks Tools - Leaf blower, string trimmer and a twin force 40v lawn mower. Moved to a new home with bugger yard so upgraded to this one. To me, Greenworks is the Apple of lawn tools. There is a thoughtfulness of their products not found in many other brands. Be it the battery indicator on the handle or the soft closing of the battery cover or the turbo mode for thick grass, these subtle features just enrich your experience with the products. This mower gets the job done as claimed. The ability of add an additional battery is awesome as well.
Date published: 2020-04-18
Rated 5 out of 5 by from Four years old and still going I purchased my 40V G-Max mower four years ago, and this mower is phenomenal. Living in Arizona, I have to mow year round, and even after all of this time the mower is still going strong. The body has held up to our harsh summers, the batteries still deliver the performance needed (although I did add a third battery to the mix for the times when the grass is extremely thick), and I have never had a problem getting through my 1/4 acre of grass. The mower is extremely lightweight, and it is so quiet that I have no problem mowing early in the morning or later in the evening when the kids are asleep. I have occasionally had problems with the mower stalling out when mulching, but this is typically because of dull blades. I pull them off with ease, sharpen them, and get back to business. This has been one fantastic mower, and it doesn't seem to be slowing down even after four years of hard use.
Date published: 2017-09-17
Rated 4 out of 5 by from Great Battery Life and Cuts - Unsure w/Twin Blades I've had the Greenworks 40V Electric Mower for about a year now and am just getting started this summer with mowing. Last year, I was a bit skeptical on the twin blade system because in our area of the neighborhood we have several dandelion patches. The mower would cut through most of them, but didn't "ramp-up" when I needed the power. This year it seems better and I'm not sure if the mower is just broke-in (only used it about 3 times before the cold came) or if I am more familiar with how to get the best out of it. The blades are now one notch from the top and my lawn looks much better with longer grass. I'm pleased this year to the point that I now own the Greenworks 13" trimmer, a blower, and chainsaw. Lastly, the convenience is awesome with a push button start, no gas, no fumes, no oil changes, no spark plugs, and no cords to pull! Greenworks is doing great and I hope their products only continue to get better.
Date published: 2017-05-11
Rated 2 out of 5 by from Very light but poor cut quality I purchased this off Amazon less than a year ago and although the mower is quiet, light and easy to maneuver, I don't believe the two blade design is the best as it leave a lot of stands of grass sticking up and I need to do many second passes to get the lawn looking as it should. I wrote on my Amazon review that the power save feature (where the mower speeds up in thicker grass) should be manually triggered -- that would likely saved me from doing repeated second passes. I saw where Greenworks recommended to someone else on Amazon to raise the deck higher but that just means you need to lower it and again... make multiple passes. I would like to recommend this lawnmower but it takes me double the time to cut the lawn now and I know there are better options that can do it -- sadly I wasted $300+ on this ... lesson learned.
Date published: 2017-06-11
Rated 5 out of 5 by from LOVE THIS MOWER! My daughter purchased one of these mowers last fall and absolutely loves it. This spring when my husband and I were considering purchasing a new mower, we had a chance to try out our daugher's. After years of dealing with gas, oil, pulling the cord to get it started and the weight of a traditional mower, we purchased this mower for our yard. I absolutely love it! So easy to start and use. Not as heavy and so quiet our neighbor commented that he didn't even know I was mowing. I just make sure to keep the batteries charged and I'm ready to go. Will be replacing other gas powered yard equipment in the near future. Wonderful product. I asked for this mower for my Mother's Day gift and its the best gift yet.
Date published: 2018-05-27
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I'm in need of a replacement motor and have been looking for one on your website with no luck of locating one. I would like to no if this is a replacement part you offer or if there is another company you could refer me too? Thank you for your help.

Asked by: AcSl8ter
Hello AcSl8ter, Currently this part is out of stock. Please contact us at 1-888-909-6757 (1-888-90WORKS) and we will gladly assist you with this. *Please be advised due to the current pandemic COVID-19 we are experiencing delays and longer than normal wait times. Thank you for your patience and understanding.*
Answered by: GW Customer Agent
Date published: 2020-06-29

Do you sell replacement wheels for this model?

Asked by: MikeN
Hello MikeN, You can use the part number from your manual to order parts from our third party parts site here: https://greenworks.ordertree.com/
Answered by: GreenWorks Support
Date published: 2020-06-24

What is the number for a replacement grass catcher

Asked by: wrenn
Hello wrenn, Thank you for your question. If you have an item number (located in the manual) you can order from our third-party part site here: https://greenworks.ordertree.com/ Replacement parts can also be ordered directly from GreenWorks kindly contact us at 1-888-909-6757 (1-888-90WORKS).
Answered by: GW Customer Agent
Date published: 2020-06-11

I purchased my mower from Amazon 2 years ago. The bearings on one of the motors are bad. Would this be covered under warranty? Or, are repair parts available?

Asked by: MYLEE
Hello MYLEE, We do offer a limited 4-year manufacturer's warranty. You can also purchase replacement parts here: https://greenworks.ordertree.com/ For warranty assistance, please contact us at 1-888-909-6757 or by email to info@greenworkstools.com. Please note we are currently experiencing delays due to the current pandemic COVID-19. We apologize and thank you for your patience and understanding.
Answered by: GWT Customer Support
Date published: 2020-06-10

Batteries are charged and mower will not start.

Asked by: Teddie
Hello Teddie, Please make sure the unit is started in the correct sequence. If the start up is done any other way the unit will not turn on. Make sure to push and hold the safety start up button first, then pull up the bail lever, once the unit starts you can release the safety button and continue to hold onto the bail handle. Please see the video guide below: https://www.youtube.com/watch?v=HJMj4ha5pWs
Answered by: GWT Customer Support
Date published: 2020-06-09

How to remove the batteries

Asked by: Stinson
Hello Stinson, You should be able to hold the battery lock latch down and firmly grasp the battery and pull upwards. Here's a video guide that may help: https://www.youtube.com/watch?v=eWMTVj6LldE
Answered by: GWT Customer Support
Date published: 2020-06-09

My battery won't stay charged

Asked by: Lori V
Hello Lori V, We are sorry to hear about the experience you have encountered with this battery. Here are a few suggestions to check out. 1) Ensure that the charger is working. When the charger is plugged in you should see a solid red light on the left to indicate power. When the battery is inserted, the right light should also ignite solid red to indicate that it is charging. If this light on the right is not igniting or is flashing red, this may indicate an issue and we would be interested in hearing more about this. 2) Ensure that the battery has been fully inserted into the charger. Sometimes this requires a firm push into place to make sure that it has been properly seated. 3) Try resetting the charger. To do this, simply unplug it for approximately 10 minutes and then plug it back in and try reinserting the battery. If the charger has been plugged in for extended periods of time, this can sometimes cause the charger to malfunction. If you have tried these suggestions and are still experiencing an issue, please kindly contact us at 1-888-909-6757 (1-888-90WORKS) or by email on info@greenworkstools.com
Answered by: GW Customer Agent
Date published: 2020-06-05

Are you supposed to run mower with both batteries inserted?

Asked by: El88
Hello El88, No, the unit does not require both batteries to run.
Answered by: GWT Customer Support
Date published: 2020-06-04
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Deck Size:
20 Inch
Deck Material:
Deck Type:
Cutting Heights:
5 Position
Max. Cutting Height:
3 3/8 Inch
Min. Cutting Height:
1 3/4 Inch
Front Wheels:
7 Inch
Rear Wheels:
10 Inch
Vertical Storage:
Smart Cut Technology:
Discharge Features:
Tool Warranty:
3 Year
Battery Warranty:
3 year
Battery Capacity:
Battery Capacity 2:
Replacement Charger:
Replacement Battery:
29472, 29462
Replacement Mower Blades:
  • (1) 40V Cordless 20" Lawn Mower
  • (1) Grass Collection Bag
  • (1) 4.0 Ah Battery
  • (1) 2.0 Ah Battery
  • (1) Battery Charger
  • (1) Owner's Manual
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