Dewalt DCST990H1 40V Max Cordless 15″ Outdoor String Trimmer – First Look


DeWALT may not be first to the plate every time, but when they do it is a quality tested product.  When they announced a new outdoor power equipment line last year I was a bit skeptical.  We have seen lithium hit the home market with good success but for the professional?  .

We finally have these tools in our hands and the weather isn’t cooperating with us.  However we got a good chance to give the string trimmer a try.  This trimmer says pro all over it, from the quality build to the near perfect ergonomics and balance. The tool is available in 2 battery combinations  The DCST990H1 comes with a  6.0 AH battery and the DCST990M1 with a 4.0 AH battery.  It weighs in at 13.9 lbs which is heavier than some gas trimmers but the good balance helps detract from that.  The standard dual line bump feed takes standard 0.080″ line, it is relatively easy to restring.  It has a metal gear case that will stand up to abuse of being used in a commercial application.

Briefly using the trimmer we noticed it had a lot of power.  You cannot tell the difference between this and gas when it comes to power.  Electric has more torque than gas and it shows in this application.  It has a low and a high switch which runs at 5600 or 6600 rpm.  The trigger is variable so you can dial in any speed you want. The only downfall I can see compared to gas is run time.  We haven’t had a chance to test run time yet, but I know the professional demands it.  The 6.0 Ah battery should be a huge help and with 2 or 3 batteries on hand you can get all day run time. it took roughly an hour to charge the 4.0 battery.  The 6.0 AH battery will take longer, I would like to see faster charge times. We will re-visit this soon when we have some time with it out in the field.


  1. Man this one looks awesome and I do need a new blower but damn I don’t know if I need another battery platform 🙁

  2. Nice review guys, especially with nothing growing outside. I don’t believe many professional landscapers cutting lawns all day would find this tool a replacement for gas powered trimmers. Just too heavy and uses only 0.08 inch string. Nowhere can I find the run-time listed, but can guess it’s not acceptable for professional use.

    I see this tool useful for the homeowner that doesn’t want to deal with gas powered trimmers, and dislikes dragging a cord around.

  3. looks close to buying stihl cordless ..see if this arrives at local home depot or
    stihl older gas model is heavy ..close to dewalt…no more chasing expensive hard to find ultra
    oil for stihl…want one,now for mowing small yard, be perfect for me..

  4. Hey dan, do you know if that battery would fit in dewalts 36v circular saw, it would be great to have some higher amp hour batteries for it, the one it came with is only 2 amp hours but it still lasts half a day of heavy use.

  5. Awesome power!. I personally really power tools, particularly DEWALT tools – superb quality and fair pricing for what you get. This strimmer is so very easy to use, had it charged in less than an hour and was out cutting for 2 hours. I cut thick heavy brush and grass clumps with no problem at all. Even after the 2 hours the srimmer still had a lot of power remaining..

  6. Looks nice, but a bit heavy. I have a small yard so it may not matter to me. I’m also looking to upgrade to battery or gas. My electric trimmer/edger has done me well but I want the easy of movement around the front & back yard. This is another platform that I need to consider. Laters TIA

  7. Just used mine today. Absolutely love it! The blower is great too! On demand power. Simple shut down and fire right back up.

  8. It works great I have a .3 acre yard but I maintain an area across the street frome me I have a fence so I do weed eating for at least an acre and it will do it I have the blower as well and that is the best thing and the only thing I don’t like is the head of the unit it is weak and where do u get a replacement it will break For sure but it is all worth it I really want the hedge trimmers and I will get it soon they need a chainsaw like echo has and it may work. Get it you won’t b disappointed I have an echo gas trimmer and I reach for this it is lighter and quiet

  9. I have owned this for about a month and a half. I have a heavily landscaped 1/3 acre yard. The battery (6amp) has plenty of power left at the end of trimming and edging the whole property. I liked this so much that I bought the Dewalt 40v blower. Then lowes offered a mail in rebate for a free battery. So now I have three batteries which is plenty. I am so happy to never have to mess with gas weed-eaters (I have run through three husqvarnas).

    A few notes:

    Don’t underestimate the convenience of trigger starting. You can weed-eat/edge a few feet and set it down… leave it for an hour a day or two seconds. you never need to worry about a temperamental engine.

    This Dewalt has allot of power, but I don’t think it can match the higher end weed eaters (Husqvarna, stihle, etc.)

    I recommend a backup battery to reduce load on batteries and for ease of mind.

    I can not see this unit being used by pros… If the batteries were $20/piece rather than $200 than maybe.

  10. I absolutely love this. I admit I’m a black and yellow fan and do own their 20v line but this is a great product and with my larger (2/3 acre) yard, I’m very happy I stepped up to the 40V. I considered going with a different brand to give a different manufacturer a shot but my brother runs a lawn crew and absolutely swears by the 40v dewalt. He does go through 4 or 5 batteries a day but for a busy lawn crew, that is a small price to pay for NEVER having engine problems. Great product and an excellent review video guys.

  11. Thanks for sharing this very informative product review. A friend got this from eBay and unfortunately ditched it after a couple of months.


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