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  • Battery University........

    I know, I know! You guys are getting tired of hearing from me. This site has some pretty cool stuff about LI battery technology though:
    http://www.batteryuniversity.com/parttwo-34.htm

  • #2
    Re: Battery University........

    Useful stuff ... focused lots on notebook batts versus high current draw. I just called Milwaukee to 're-verify' their L-I batt warranty and they state 1000 charge cycles (monitored by a chip in the Vxx batts) or 2 years (born-on date). That (1000) is double what the University info states, so things must be changing rapidly.

    I'm now pondering the many posts, talking about several years of Ni-Cad power tool batt usage, and perhaps 'revaluing' its current relevance. I also recall an article ... somewhere ? ... and the gist of it was that Ni-Cads handled heavy current draw situations better than Nickel Metal Hydride.

    I wonder how this will sort out as lots more field input gets reviewed comparing Ni-Cad and L-I. There are certainly lots of serious users out there who have high appreciation for their 'quality' (XPR, etc.) Ni-Cad batts.

    Tom B

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    • #3
      Re: Battery University........

      Talking about NIMH batteries, I've been using the AA's and AAA's for a couple of years now and the only problem is how fast they discharge. Now there is a Hybrid NIMH battery available, it holds it's charge for close to a year. All the benefits of a rechargable and alkaline battery. Getting back to the nicad vs lithium, I agree that in real life application we will have to wait and see how well they perform, but from all the information regarding the technonlgy of lithiums it would appear they will outperform the nicads. Too good to be true, a battery that holds a charge for a very long time, runs strong and has no memory? Imagine 1000 or more charging cycles? When it comes to my small NIMH and Lithium batteries, that means I can charge them once a week for twenty years! Is that theoretically possible? Why can't a lithium tool battery last for years if it can be charged 1000 or more times?

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      • #4
        Re: Battery University........

        Originally posted by doubtingtom View Post
        Useful stuff ... focused lots on notebook batts versus high current draw. I just called Milwaukee to 're-verify' their L-I batt warranty and they state 1000 charge cycles (monitored by a chip in the Vxx batts) or 2 years (born-on date). That (1000) is double what the University info states, so things must be changing rapidly.
        All the manufacturers make some rather outlandish claims about the cycle life of their batteries. Lithium ion averages maybe 400 to 500 full cycles. That means from the battery being fully drained to fully topped off. A half drained battery counts as half a cycle when it's topped off. Manufacturers can easily twist the numbers if they estimate people don't fully drain their batteries before recharging them. Makita is another one who makes some bold claims of 1400 cycles even though the Sony VT cells they use are specified to be 500 cycles. I would expect the Milwaukee batteries to realistically be somewhere in that range. Dewalt makes the boldest claim of 2000 cycles but their technolody is sufficiently different from the rest that its hard to tell exactly how long they last. Their cells run at lower voltage which is one of the key factors in drastically increasing the cycle life.

        The biggest drawback to lithium ion isn't the cycle life though. It's the natural deterioration of the cells. Most of them die when they simply can't hold much of a usefull charge any longer. They will loose about 20% of their capacity every year unless some very specific precautions are taken during long term storage. That said after 2 years, a Li-ion battery will hold about as much energy as a fresh NiCD so it's still not that bad. You are a lot more likely to have to dump the battery due to its yearly deterioration than reaching its cycle limit.

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        • #5
          Re: Battery University........

          Originally posted by Frankiarmz View Post
          Talking about NIMH batteries, I've been using the AA's and AAA's for a couple of years now and the only problem is how fast they discharge. Now there is a Hybrid NIMH battery available, it holds it's charge for close to a year. All the benefits of a rechargable and alkaline battery. Getting back to the nicad vs lithium, I agree that in real life application we will have to wait and see how well they perform, but from all the information regarding the technonlgy of lithiums it would appear they will outperform the nicads. Too good to be true, a battery that holds a charge for a very long time, runs strong and has no memory? Imagine 1000 or more charging cycles? When it comes to my small NIMH and Lithium batteries, that means I can charge them once a week for twenty years! Is that theoretically possible? Why can't a lithium tool battery last for years if it can be charged 1000 or more times?
          The article referenced and many others I have read regarding Lithium Ion batteries states that due to oxidation the battery eventually loses its ability to take a charge until it reaches a point where it is no longer usable. Most articles state this happens in 2-3 years depending on use condtions etc.
          ........................"Aging of lithium-ion is an issue that is often ignored. A lithium-ion battery in use typically lasts between 2-3 years. The capacity loss manifests itself in increased internal resistance caused by oxidation. Eventually, the cell resistance reaches a point where the pack can no longer deliver the stored energy although the battery may still have ample charge. For this reason, an aged battery can be kept longer in applications that draw low current as opposed to a function that demands heavy loads. Increasing internal resistance with cycle life and age is typical for cobalt-based lithium-ion, a system that is used for cell phones, cameras and laptops because of high energy density. The lower energy dense manganese-based lithium-ion, also known as spinel, maintains the internal resistance through its life but loses capacity due to chemical decompositions. Spinel is primarily used for power tools."
          Soooooooooooo one of the reasons I chose Ridgid for LI tools is with the hope that they will replace these expensive little buggers under the LSA when the oxidation demon strikes.

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          • #6
            Re: Battery University........

            When I first started this thread I wanted to take everyone right to Lithium Ion since thats our current hot button. That is somewhat of a diservice to this site as the particular section shown from that address gives the impression that all the info is sort of laptop computer oriented. Nothing could be further from the truth. Click here to start at the beginning and note the index in parts 1 and 2. Most of this was written 4-5 years ago and reflects the state of the art at that time. Certainly the basic physics remains valid....Ray
            http://www.batteryuniversity.com/index.htm
            Last edited by roadrashray; 10-17-2007, 03:44 PM.

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            • #7
              Re: Battery University........

              Well this is another disappointing fact of life I just became aware of! Your posts put me on track to doing some Internet research about Lithium batteries and the two to three year lifespan along with problems like "deep discharge" and the necessity for smart batteries to prevent discharge below a certain point were things I was completely unaware of. I can understand your reasoning with the Ridgid LTW and hope they honor the battery situation. Do you think there will be some kind of consumer outcry if after two or three years lithium battery owners will have to fork over another couple hundred or so dollars to replace their two useless lithium batteries? The article I read on problems with lithiums said that nicads and NIMH's were tougher and I was wondering if hybrid NIMH's would be a better answer for longer life tool batteries.

              Comment


              • #8
                Re: Battery University........

                Don't be too quick to think li-ion will just die prematurely. Lithium ion batteries still tend to have similar lifespans to any older technology. They can easily last 4 or 5 years, sometimes even more. Milage will vary depending on many factors but just keep in mind almost everything now a days runs on li-ion. Your laptops, cel phones, ipods, you name it. If its rechargeable chances are its lithium ion. The technology is pretty well proven. Remember Nickel based batteries also suffer capacity loss and don't hold charge after a few years either. You actually shouldn't be able to deep discharge a lithium ion battery. The built in monitoring circuitry will cut power if it gets too low. You can deep discharge a nickel battery and damage it though.

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                • #9
                  Re: Battery University........

                  Battery technology is moving along at a very fast pace and a lot of this web information is not keeping up with it.

                  There are many different Lithium battery technologies. Some of newer technologies have greatly improved the cycle life, reduced the risk of fires, improved the shelf life, and allowed the cells to be discharged much lower without damage.

                  I have had a Lithium Ion RC battery in my basement for 2 years. When I pulled it out it had 75% of it's original charge. I recharged it and it's capacity was 80% after two years. This is older technology. There is better technology today.

                  This battery probably benefited from my cool basement. Lithium Ion battery life is greatly reduced at higher temperatures. To increase their life, store them at cooler temperatures and try to not leave them in your car where temperatures can reach 160 degrees on a summer day.

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