Dewalt DCST990M1 40V MAX XR 4.0 Ah Lithium-Ion Brushless 15 in. String Trimmer

Model: dewndcst990m1
ratings        (31) Write A Review

We’re sorry, but this item is no longer available.

CA Residents
Prop 65 Warning
compliance warning icon
WARNING: Cancer and Reproductive Harm --
Dewalt DCST990M1 40V MAX XR 4.0 Ah Lithium-Ion Brushless 15 in. String Trimmer Model: dewndcst990m1

Product Features & specs :

Dewalt DCST990M1 40V MAX XR 4.0 Ah Lithium-Ion Brushless 15 in. String Trimmer

The 40V MAX String Trimmer features a patented gear drive design for amplified torque when powering through overgrowth. The bump feed head provides 15 in. of swath with DEWALT's 0.080 in. line (0.095 in. line is also compatible). The variable speed trigger offers precise power control as well as performance and runtime management with the Hi/Lo speed control switch.
  • 15 in. Cutting swath with 0.080 in. line (also accepts 0.095 in. line)
  • Patented gear drive design that powers through overgrowth
  • High-efficiency brushless motor maximizing run time and motor life
  • Variable trigger with hi/lo speed control for added power or extended runtime
  • Part of the 40V MAX system of Outdoor Power Equipment
What’s Included:
  • 40V MAX XR 4.0 Ah Lithium-Ion Brushless 15 in. String Trimmer - DCST990
  • 40V MAX 4.0 Ah Lithium-Ion Battery - DCB404
  • 40V MAX Lithium-Ion Battery Charger - DCB114
  • 0.080 in. Pre-wound Line in Spool
Power Source
UL Safety
CSA Safety
Wifi compatibility
Batteries Included
Battery Type
Starter Type
Case Included
Speed Settings
Bluetooth Compatibility
Battery Amp Hour
4 Ah
Motor Type
Blade Construction
Charge Time
1 Hour 30 Minutes
Charger Included
ETL Safety
Battery System
13 lbs.
Warranty Term
3 Year

Reviews :

4.5 / 5.0
31 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Would you recommend this product?
Yes (20)
No (2)
Powerful (18)
Easy To Use (9)
Lightweight (7)
Value (4)
Heavy (2)
Short Run Time (if applicable) (1)
Best Uses
Frequent Use (6)
Small Projects (5)
Large Projects (2)
Heavy Duty Requirements (1)
Works Great! No Fuel! Perfect!
This weed eater has been my best one yet. The spindle seems to hold more stuff then other models before. Battery life is sufficient and usually make it through the whole yard and both sides of my fence before needing charged again. I would definitely recommend to anyone wanting to stop using the obsolete gas models.
May 20, 2019
Originally posted at
Love it!!
Better than my gas trimmer.....that won’t start at all.
August 19, 2018
Originally posted at
Same story - motor grenaded in light use -
Light use for 39 months then it died, motor magnets grenaded
August 15, 2018
Originally posted at
Nice trimmer
This trimmer seems to work well. I have a fairly large yard and have used it four times. The battery just recently dropped to one green bar. Does not seem to cut as well as gas models. I think it is because the cutting line is a little week. May try it with the larger cutting line. The cutting line lasts a long time but is a little annoying to rewind. Other than that, the trimmer seems up to the job.
August 2, 2018
Originally posted at
Wow! What a string trimmer.
Let me start off by saying this string trimmer rocks. I live on a 1/4 acre lot in a 1000 square foot home. There's a lot of weeding that happens here. This trimmer will absolutely destroy grass 6 to 12 inches tall no problem. Battery life is about 30 mins or so depending on how thick the grass is. The unit is light and has super low vibration. 40 V Max XR brushless string trimmer is a no brainer. Its quiet, No mixing gas no gas fumes. A 4 year old could put 25 feet of line on the head of this trimmer in 10 min! Good job Dewalt.
July 15, 2018
Originally posted at
Would you recommend this product?
Easy To Use
needed string trimmer, no oil or gas, after reading all reviews of DeWalt cordless trimmers the choice was easy. The 40 volt. I was hoping it would be the 20 volt or 60 volt as I have many tools using those batteries , but ease of use and power all pointed to the 40 volt and I am very happy with it. Having got the 40 volt trimmer it will now be easier for me to get other 40 volt DeWalt yard tools.
June 14, 2018
over 2 years ago
Describe Yourself:
Avid Do-it-Yourselfer
I have been an avid gardener and this is the best trimmer I have ever used. It is so easy to use and I like the power generated on a battery operated trimmer.
April 17, 2018
Originally posted at
Would you recommend this product?
Easy To Use
Best Uses
Frequent Use
Best buy I have made in a long time
This machine has more power than any gas weed eater I have bought in the past. cutting mostly weeds and not grass. Use safety glasses as noted. Great to have a battery powered tool that negates all the problems with gas tools.
June 23, 2017
Describe Yourself:
Avid Do-it-Yourselfer
Would you recommend this product?
Easy To Use
Best Uses
Large Projects
Great weed wacker
This weed wacker is a beast plenty of power the dewalt line is strong and durable
May 22, 2017
Would you recommend this product?
Easy To Use
Best Uses
Small Projects
Very nice tool
I like how it cuts the weeds quickly. The battery only lasts about 30 minutes for me, but my body wants to quit before then, so it is fine. I just work until the battery drains and then go recharge it and take a break.
April 14, 2017
over 3 years ago
Describe Yourself:
Beginner- Casual Do-it-Yourselfer

Q & A :

Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 16 questions Browse 16 questions and 22 answers
how do you put new line on spool?????????????????
we have tried for over a half hour.
please help.
Michael on Jul 9, 2016
BEST ANSWER: Please contact Dewalt direct for technical support. You can reach them at 800-433-9258
Does it have shoulder strap ?
A shopper on Jul 8, 2018
BEST ANSWER: No, but I’ve heard of people rigging one up.
It is on the heavy side, but well balanced. I’ve never owned a gas trimmer, so I can’t compare but I’m very happy with my purchase... could almost cut down a tree!!!
Does it come with a charger for the battery?
A shopper on May 18, 2018
BEST ANSWER: Yes it comes with a charger.
Will the 20 volt work with the 40 volt
todd on Aug 2, 2016
BEST ANSWER: No, the two systems are not cross compatible
Where can I get a replacement spool of string
Oly on May 7, 2016
BEST ANSWER: Cpo does carry replacement spool of sting or this item.
Dewalt DWO1DT802 0.080 in. x 225 ft. String Trimmer Line $13.99
Dewalt DWO1DT801 0.080 in. x 50 ft. String Trimmer Line $6.99
Is the recon 40 volt dewalt string trimmer included in the free battery rebate program
Flapp on Apr 27, 2016
BEST ANSWER: No,Dewalt is not running a free battery promotion for the string trimmer.
how long of time in one continual use do the battery last ?
Unlucky on Dec 11, 2015
BEST ANSWER: The battery run time will range from 15-30 minutes based on usage
What is the expected life time of the battery for normal home usage?
RB on Jun 14, 2015
BEST ANSWER: The battery lasts about an hour.
Does DeWalt make an edger
PONCHO on Jun 5, 2015
BEST ANSWER: They make a trimmer but not an edger at this time.
How long does it take to recharge the battery? Also how long do these 40V batteries last?
Yard Diva on May 10, 2015
BEST ANSWER: This kit comes with a 45 minute charger. Theoretically, the battery will last 45-55 minutes. Practically, it depends on how hard you push the unit.