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Dewalt 18V XRP Battery. 10Min Runtime?

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  • Dewalt 18V XRP Battery. 10Min Runtime?

    First off sorry for posting about dewalt tools on a rigid forum, I was going to post on the dewalt forum, but there was only 2 people viewing the entire forum.

    Anyways, yesterday I bought the dewalt DC411KA kit. It's an 18V Cut-off tool (4 1/2") with 2 18v XRP batteries, and accessories. I fully charged both XRP batteries last night, and the charger displayed a constant red light, meaning they charged successfully.

    Today at work I was removing old paint, and they only lasted 10 minutes each!!! What is the deal? I know it works the batteries pretty hard, but i should get AT LEAST half an hour to an hour right? I'm convinced the batteries are defective, but I just want to ask some people based on their experience.

    Thanks in advance.

    Oh and if the batteries are working just fine and this is normal, then good-bye dewalt, hello rigid

  • #2
    Re: Dewalt 18V XRP Battery. 10Min Runtime?

    I am a frequent user on the DEWALT site and would have been more than happy to answer your question over there!

    Comment


    • #3
      Re: Dewalt 18V XRP Battery. 10Min Runtime?

      Haha, it seemed like a nice forum but I was looking for a quick reply.

      So could you just answer my question here, or are you going to make me register and post it over there?

      Comment


      • #4
        Re: Dewalt 18V XRP Battery. 10Min Runtime?

        Can anyone help me out please? I've been searching google and various forums for the past two hours trying to get an estimate on the runtime of the battery.. I know there are many variables so just a general answer?

        Comment


        • #5
          Re: Dewalt 18V XRP Battery. 10Min Runtime?

          IT is the TOOL not the batteries.

          on my Dewalt 18 volt cut off tool it eats batteries, 10 Min's of run time is a lot on it, some times just cutting off 6 to 8 30d nails on post, the tool is what not what I had hoped for,
          It really can not take much of a grinding job, I think I read one person only getting one or two 1/2 re-bars cut with a cut off wheel per charge,

          IN your situation (job use) I do not know what kind of life one should get,

          it doesn't in my opinion even come close to a cored version,

          the stars in the reviews seem to be more encouraging than the statements, from amazon,
          http://www.amazon.com/Bare-Tool-DC41...R2NJSN5PFAPDCH

          only one review http://www.dealtime.com/xPO-Dewalt-D...h-Cut-Off-Tool many good things about but quoting the down side of the tools review here,(complete version of the review, http://www.dealtime.com/xPR-Dewalt-D...D-469796884100
          The down side is that the batteries quite honestly can be burned up in as little as five minutes. I'm sure it depends on the application, but I would have to keep five or six batteries in my bag often times to complete a project. As I said, I was usually using this tool for cutting through solid steel angle irons, and thus the quick battery expenditure. The cut off wheels, incidentally, helped. And learning the best technique for cutting also extended the life of a batter, but I'd often use one batter just to cut through one angle. That left me many times wishing for an electric version of the same tool, which I often borrowed from a nearby steelworker if one was available, after my batteries ran out!

          All in all, however, this is a very useful tool for what it's worth. Again, it's particularly valuable when you find yourself unable to plug in somewhere. But if you have any length of work, make sure you bring several spare batteries. The bag it comes with comes in very handy for all those spare batteries!
          On other tools I find the battery life more than acceptable for most things, but the cut off tool sucks the battery dry faster than any other tool that I have, on any task.
          Last edited by BHD; 03-17-2010, 01:16 AM.
          Push sticks/blocks Save Fingers
          ~~~~~~~~~~~~~~~~~~~
          "The true measure of a man is how he treats someone who can do him absolutely no good."
          attributed to Samuel Johnson
          ~~~~~~~~~~~~~~~~~~~
          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

          Comment


          • #6
            Re: Dewalt 18V XRP Battery. 10Min Runtime?

            Originally posted by kbud253 View Post
            First off sorry for posting about dewalt tools on a rigid forum, I was going to post on the dewalt forum, but there was only 2 people viewing the entire forum.

            Anyways, yesterday I bought the dewalt DC411KA kit. It's an 18V Cut-off tool (4 1/2") with 2 18v XRP batteries, and accessories. I fully charged both XRP batteries last night, and the charger displayed a constant red light, meaning they charged successfully.

            Today at work I was removing old paint, and they only lasted 10 minutes each!!! What is the deal? I know it works the batteries pretty hard, but i should get AT LEAST half an hour to an hour right? I'm convinced the batteries are defective, but I just want to ask some people based on their experience.

            Thanks in advance.

            Oh and if the batteries are working just fine and this is normal, then good-bye dewalt, hello rigid
            Hi, I tested most cordless grinders and ALL do have very short runtime.

            My video: http://www.youtube.com/watch?v=g3zC-Tt4w8E

            DC410 cuts 14-20 pieces of 1/2 rebar with 1mm disc. DC411 is about 20% more efficient than DC410. Your runtime is correct. Battery is 2.4 Ah or 2.4 * 60 minutes = 144 A*minutes
            Now 144/10 = 14.4 Amperes - typical mean discharge current. So your runtime is correct. That's why I have a 36v model that has 2.5x runtime of a 18v model (more efficient at higher voltage). Neither the grinder nor the batteries are defective, you are using the wrong tool for your application. It's like mixing concrete with a kitchen mixer and complaining the motor is defective.

            DC411 is more efficient than Makita BGA452 and Milwaukee V28 (V28 has longer runtime because of bigger battery tho).

            Ridgid doesn't even make the grinder. If you really want to please Ridgid, buy a 18v Milwaukee grinder, it has exact same battery as Ridgid (inside). You will be even more disappointed as it is 9000 rpm, which translates into 1.4x less torque than DC411. They are all called "cut off tools" and not "grinders" by the manufacturers for that very reason.

            My comparison: http://toolhacker.com/2009/03/makita...ldess-grinder/
            Last edited by DRC-Wartex; 03-19-2010, 12:33 AM.

            Comment


            • #7
              Re: Dewalt 18V XRP Battery. 10Min Runtime?

              Originally posted by DRC-Wartex View Post
              Hi, I tested most cordless grinders and ALL do have very short runtime.

              My video: http://www.youtube.com/watch?v=g3zC-Tt4w8E

              DC410 cuts 14-20 pieces of 1/2 rebar with 1mm disc. DC411 is about 20% more efficient than DC410. Your runtime is correct. Battery is 2.4 Ah or 2.4 * 60 minutes = 144 A*minutes
              Now 144/10 = 14.4 Amperes - typical mean discharge current. So your runtime is correct. That's why I have a 36v model that has 2.5x runtime of a 18v model (more efficient at higher voltage). Neither the grinder nor the batteries are defective, you are using the wrong tool for your application. It's like mixing concrete with a kitchen mixer and complaining the motor is defective.

              DC411 is more efficient than Makita BGA452 and Milwaukee V28 (V28 has longer runtime because of bigger battery tho).

              Ridgid doesn't even make the grinder. If you really want to please Ridgid, buy a 18v Milwaukee grinder, it has exact same battery as Ridgid (inside). You will be even more disappointed as it is 9000 rpm, which translates into 1.4x less torque than DC411. They are all called "cut off tools" and not "grinders" by the manufacturers for that very reason.

              My comparison: http://toolhacker.com/2009/03/makita...ldess-grinder/
              explain the rpm to torque ratio thing to me because I dont understand. Is it the same reason the 14.4 impact drives faster and has more rpms? because the torque is lower? Is that directly related?

              Comment


              • #8
                Re: Dewalt 18V XRP Battery. 10Min Runtime?

                for a give amount of power, say horse power, it is made of RPM and torque,

                torque is the amount of power in the rotation, usually measured some distance out and amount of pressure it produces at that distance, say so many foot pounds, that would be X number of pounds of push at one foot away from the center of the shaft,
                (on a spinning object at one time this was measured with a brake type system),

                now say you have 10 pounds of pressure at one foot away from the shaft, and this object turns at one revolution per min, (any pressure greater than 10 pounds slows or stops the shaft,)

                no saw the shaft is turning at 100 rpm and still has 10 ft lbs on the shaft, you would have 100 times the over all power,

                so you read this engine puts out 100 horse power,

                and it is in a small car, and then you read a add for a farm tractor, and it has 100 horse power, how can that be,

                tractor can pull a 4 bottom plow 12 inches deep in soil, and the car could not pull the tractor down the road, but the car can race down the road at 100 mph, and the tractor at it best will do 18 mph and slows down on hills, the difference is torque and RPMs, they both have the same power, but the way that power is produced and used is different, the RPMs and the TORQUE is entirely different, the constant is the horse power, and the ratio between the rpms to torque is the variable.

                on a impact wrench, it is more like taking a wrench and a hammer and tapping on the end of the wrench, since one does not have equal horse power on the different hammer sizes, you can not just say yes the smaller wrenches turn faster with less torque,

                yes normally the smaller the drive size is the higher the RPM and less torque they produce,
                but also the smaller sizes do not have the over all power as a larger wrench,

                but the relation ship is there, you take a one 1" impact wrench, (bigger motor) but they drive the speed slower and the hammer inside the wrench is much heaver than in a small wrench, (I would think the relation ship of the hammer weight and the speed is more the relation ship, here which in turn has the correlation to the over all HP, but in this case the speed of rotation and weight of the hammer is made optimize) and then the HP of the tool is then designed to keep the speed and torque produced at the specification wanted,

                say for illustration you take a hammer and put a hinge on the handle and put the hing on a shaft, and hook it to your drill, and turn on the drill and spin the hammer around and around, now slowly move the spinning hammer over to a anvil edge, and let it strike it, and slip off depending on hammer size and speed you try to run the hammer there would be different efficiency of the strike, if you would try it with a smaller hammer or a shorter handle, you would get different results, possibly drive with drill of different speeds and powers may make a large differences as well,

                but for the most part the smaller the fastener your working on the high speed taps with a lite hammer is preferred than a few heavy whacks with a heavy hammer, now on a large fastener you will need the heaver whacks as there is more resistances and frictions, and you could tap on it all day with the lite hammer and never accomplish the goal, as you never over come the friction or resistances,

                (my explanation of impacts may have muddied the water for you and if it did I am sorry),

                but yes there is a relationship between the speed and the torque but on impacts your changing the over power as well, it is hard to compare even in tractors a 25 hp tractor to a 50 hp tractor to a 150 hp tractor, there made differently for different taskes and jobs, even tho there all tractors, (the 150 HP tractor would make a lousy tractor to mow a yard with where the 25hp tractor would make a nice unit for that),
                Last edited by BHD; 03-20-2010, 10:02 AM.
                Push sticks/blocks Save Fingers
                ~~~~~~~~~~~~~~~~~~~
                "The true measure of a man is how he treats someone who can do him absolutely no good."
                attributed to Samuel Johnson
                ~~~~~~~~~~~~~~~~~~~
                PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                Comment


                • #9
                  Re: Dewalt 18V XRP Battery. 10Min Runtime?

                  Originally posted by pesciwasp View Post
                  explain the rpm to torque ratio thing to me because I dont understand. Is it the same reason the 14.4 impact drives faster and has more rpms? because the torque is lower? Is that directly related?
                  I've got an even better explanation than BHD (his explanation is 100% correct but cumbersome): if you ever rode a bicycle, think of the gearing (sprockets). Your leg muscles can only produce certain maximum power. So when you start off, you use the biggest sprocket as it gives you the highest torque at the wheel, but slow speed. As you gain speed, you start switching to smaller sprocket, it gives you high speed at the wheel but much smaller torque. So for a given amount of power, torque and RPM are inversely proportional.

                  Depending on how the grinder/drill/impact etc is geared, you get either high torque and low RPM, or low torque and high RPM.

                  If the motor gear has 10 teeth and the grinder spindle gear has 100, you will get 1/10th of the speed on your spindle but 10x the torque of the motor.

                  Typical power tool motor runs 30k RPM, so if a grinder is running at 10k RPM, there is a 3:1 tooth ratio in the gearbox.

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