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  • Lithium Ion Fact or Fiction

    There is a lot of information on the internet touting Lithium Ion Batteries praises and a great deal of it is exaggerations, over statements and some flat out fabrication. You will even see some of that here on the forum. So lets separate fact from fiction.

    First up Lithium Ion Batteries is a generic description as there are dozens of chemistries. Yes I did use the word chemistry and the first myth to bust. Some would leave you to believe Li batteries do not involve chemical reactions and is pure Ion exchange. If that were true they would last forever. Fact is there are chemical reactions within the cell and like all batteries limit their life cycle. Li battery cycle life runs as low as 50 cycles and up to 1000-1500 cycles. Li batteries use organic electrolyte, and organic materials and solutions break down with heating, cooling, and aging.
    Before I identify the 4 major chemistries it is necessary to understand some terms. So here we go.

    State of Charge (SOC) An expression of the battery present capacity as a percentage from 0 to 100%. Regardless of battery chemistry the Open Circuit Voltage (OCV) is used to get a rough idea and is not accurate.

    Depth of Discharge (DoD) is opposite and inverse of SOC. If a battery has an SOC of 80%, then DOD will be 20%. They are inter-exchangeable.

    Open Circuit Voltage (OCV) is the voltage between the battery positive and negative terminals that is not connected to anything and has been allowed to rest.

    Nominal Voltage is normal referenced voltage of the cell, sometimes called normal. Example Lead Acid batteries are 2 volts. Li batteries range from 2.5 to 3.8 volts. Nominal voltage indicates Specific Power.

    Amp Hours is a mathematical expression of a battery given capacity. Amp Hours = Amps x Hours. From that equation we can also state Amps = Amp Hours / Hours, and Hours = Amp Hours / Amps. Example a 100 AH battery can supply 5 amps x 20 hours.

    C-Rate describes a battery discharge current time to normalize battery capacity. C-Rates vary vastly within types and chemistries. Where C = Battery Amp Hour Capacity. Example if you had a 100 AH battery and discharged it at 2C would be 200 amps and take 30 minutes. Under charge conditions you might see it expressed as C/2 and using the 100 AH example would be 50 amps and take 2 hours.

    Specific Energy Wh/kg. Nominal energy (watt hour) per unit of mass. Very important number to know. Lead Acid batteries range from 40 to 70Wh/kg, and Li ranges from 30 to 300wh/kg. Higher is generally better, but the higher the number, the more unstable and dangerous the battery. Thus why some Li batteries are extremely dangerous.

    Energy Density Wh/l determines energy (watt hours) per volume. Higher is better but like Specific Energy the higher the Energy Density, the more unstable and dangerous the battery is.

    Specific Power W/kg, not to be confused with Specific Energy. Is the Power in watts per mass.

    Power Density W/l Is power in watts per volume.

    Battery Watt Hour Capacity = Battery Nominal Voltage x Amp Hours

    Time to get to the 4 most commonly used Li battery chemistries. There are dozens, many have come and gone, and some have no practical use. I will start with the highest Specific Energy and work to the lowest.

    LCO LiCoO2 (ICR)

    Voltage = 3.6 volts, range 2.5 to 4.2 volts
    Specific Energy = 150 to 240 Wh/kg
    Charge C-Rate = 1C max, C/2 recommended. High charge rates shortens cylcle life
    Discharge C-Rate = 1C to 2C relatively low Specific Power
    Uses = Tesla EV & Power Wall, Tablets, Cell Phones, Lap Tops, and Cameras.
    Cycle Life = 500 typical.
    Cost = $0.60 to $1.00 per watt hour

    LCO are the bad boys of lithium ion batteries and give lithium Ion batteries a bad name. They are the reason they cannot be shipped on airplanes and no shipping company wants to handle them. Think Galaxy 6 fires, laptop fires, Hover Board fires, exploding batteries. So why have them? Simple it is the only way to have an EV get 300 miles per charge. They have the highest SPECIFIC ENERGY of any battery made with only moderate Specific Power aka C-Rate of roughly 2 to 3.

    They are used in Cell phones, lap tops, and only one EV manufacture dares to use them. That would be Tesla motors, and Tesla Power Wall. Both the current S-Series model and the Power Wall use the exact same cell made by Panasonic NCR18650B cell is unquestionable the cream of the crop of NCO cells. No better NCO cell exist. As stated they cannot be shipped by plane and not many overseas shipping carriers will handle them because they are too dangerous. Now you know why Tesla wanted to build the Giga Factory. They will manufacture the cells under license and royalty agreements from Panasonic.

    LCO batteries require extensive battery management systems closely controlling temperature, charge rates, discharge rates, and most importantly voltage. They will not tolerate any over voltages or over charging. They are prone to thermal runaway, and are known to catch on fire while in storage doing nothing. Tesla vehicles and Power Wall use both cooling and heating to control these bad boys.

    I encourage you to look at the spec sheet and note Cycle Life claimed by the manufacture of the battery of 500 cycles. Than ask yourself if Tesla fabricated the Power Wall claim of 10,000 cycles. Anyone who tells you Li batteries have 10,000 cycles drank the Li Kool-Ade.

    NMC LiNiMNCoO2 (INR)

    Voltage = 3.7 volts, range 2.0 to 4.25 volts
    Specific Energy = 120 to 200 Wh/kg
    Charge C-Rate = Up to 3C recommended 1C
    Discharge C-Rate = 10C continuous, 20C burst.
    Uses = EV E-Bikes, Power Tools, Medical, Industrial, Scientific. Stoners, Renewable Energy Storage
    Cycle Life = 500 to 1000.
    Cost = $0.70 to $1.00 watt hour.

    NMC is the 2nd generation of Cobalt Manganese family with Nickle added to improve C-Rate. NMC is about the best chemistry in the Li battery line up. It has the high Specific Energy of Cobalt, the safety of Manganese, and with the addition of Nickle makes them a high C-Rate . There are the default battery of choice for EV used by Nisan, Chevy Volt, and BMW. Additionally they are the 1st choice for Stoners in Vape Pipes and E-Cigarettes. They are used extensively in industrial/science application and power tools.

    They require very little Battery Management. If matched cells are used no BMS is required other than cell monitoring and Low Voltage Cut-Off. As such makes them a fairly safe chemistry. Sony and LG make the two best cells on the market Most popular is the Sony VTC5A. Their high Specific Energy and Specific Power make them very useful for high demand applications requiring good cycle life and safety.

    LMO LiMn2O4 (IMR)

    Voltage = 3.7 volts, range 2.0 to 4.25 volts
    Specific Energy = 100 to 150 Wh/kg
    Charge C-Rate = 1C max, C/2 recommended
    Discharge C-Rate = 2C typical some up to 4C used in early Nissan Leaf
    Uses = Power Tools, Medical and electric drive trains
    Cycle Life = 100 to 400
    Cost = $0.80 to $1.20 watt hour.

    LMO are the first generation Manganese cells and still popular. They were used in the first generation Nissan Leaf. Eventually they will fade off to 8-Track land due to the 2nd generation NMC cells discussed above.

    As Manganese they are a fairly safe and require little battery management. The downside to them is they nave lower Specific Energy and Specific Power as compared to NMC, and fairly low cycle life. One of the most popular is cells is LGB1 18650.

    LFP LiFePO4 (IFR)

    Voltage = 3.2 TO 3.37 volts, range 2.0 to 3.6 volts
    Specific Energy = 80 TO 100Wh/kg
    Charge C-Rate = 1C max, C/2 recommended
    Discharge C-Rate = 3C to 30C depending on manufacture
    Uses = Power Tools, Medical and electric drive trains
    Cycle Life = 800 to 1500 depending on manufacture and DOD
    Cost = $0.45 to $5.00 watt hour. Ouch!


    When LFP was introduced into the market was touted as the Holy Grail of batteries and would dominate the battery market putting an end to all battery problems. Manufactures claimed them to be the safest and longest lived Li battery ever made which was true. However many manufactures went out of business or bankrupt like A123 Systems as the market was just not out there for them.

    So what happened? First issue is there lower 3.2 volt nominal voltage, which means they had low Specific Energy which killed the largest market they were targeted at EVs. Their Specific Energy is not much better than lead acid. So to get any significant mileage distance out of them would require too much battery weight. About the best they could do is 50 to 75 miles. Adding more batteries would be futile resulting in no net gain in mileage due to the extra weight. You just hit a brick wall. Higher voltage Cobalt variants have 2 to 3 times higher Specific Energy. Think of it this way. The Tesla 900 pound LCO battery would take 2700 pounds in LFP. That is more the curb weight of the Tesla Roadster. Lastly was cycle like is just disappointing. In short they were over hyped.

    One market they did find is the Lead Acid drop in replacement. The nominal 3.2 volts is a perfect match for lead acid batteries market in even number of cells. Example 2S = 6.4 volts, 4S = 12.8 volts, 8S 25.6 volts and so on. If you have a lead acid battery charger, you can charge LFP cells. However other than being somewhat lighter in weight than Lead Acid batteries did not offer the user advantages unless weight is mission critical. The last and most significant reason LFP did not take off is they cost 3 to 10 times more than Lead Acid for a given capacity, and do not offer longer cycle life. Mid end Pb batteries have 2 to 3 times longer cycle life. So if there is nothing to gain, why would a consumer pay more?

    On the plus side LFP is the safest of all the Li batteries, and do not require much Battery Management. Although they do not have high Specific Energy, they do have very good Specific Power which again means higher C-Rates which make them good candidates for high discharge rate if weight and space is not an issue. So they have found their way into the power tool market, a few other high power demand applications, and energy storage from renewable energy like solar if you are willing to pay up for it and take chances with over discharges.

    Without question A123 Systems make the best and longest lasting LFP cells. There is no better LFP battery on the market. Cycle life is 800 to 1200 cycles depending of DOD. They come in cylindrical (18650 and 26650), Pouch, and Prismatic formats. Before you rush out and buy them save your pennies because these cells are the most expensive lithium battery out there They are 3.3 volt 1.1 AH and priced at roughly $4.50 for a 18650 format or $1.20-wH.

    For DIY solar there are the Chinese made Large Format Prismatic cells. There are 4 manufactures, and 3 of the 4 of them are remakes of now bankrupt Thundersky, and the forth is GBS. The 3 survivors after Thundesky bankruptcy is CALB, Winston, and Sinopoly. Of the 3 CALB is the best but is not saying much. In terms of quality, they rank dead last in performance, quality, and cycle life. About all they offer is the lowest price of $0.45-Wh or about 2 to 3 times higher than quality Pb batteries. So if you plan going this route, buyer beware.

    Well to wrap things up there are other Li Battery types out there. One in particular is LCO or Lithium Tiitanate. When this author first heard about them got really excited because this chemistry is capable of 5000 to 10,000 cycles. They are not readily available to the public and there are only 4 or 5 manufactures, Toshiba and Altairnano to name a 2 of them . The have two huge drawbacks. Nominal voltage is 2.4 volts making Specific Energy of roughly 40 to 50 wH/kg, the same as Pb batteries so there is no weight or size reduction. That eliminates them EVs. Second downside is cost of $5 to $8-wH. They are pretty much only available to NASA and military contractors. Both NASA and Military use them as NiCd replacement and used for liquid fuel rockets. There huge advantage is there extraordinary Specific Power of 3000 to 5000 W/kg. They can be charged at 5C (less than 15 minutes), and discharge at 30C (2 minutes). If they ever get the cost down can be a game changer in utility energy storage.
    Last edited by Sunking; 01-18-2018, 03:34 PM.
    MSEE, PE

  • #2
    FACT CHECK

    Originally posted by Sunking View Post
    They are used in Cell phones, lap tops, and only one EV manufacture dares to use them. That would be Tesla motors, and Tesla Power Wall. Both the current S-Series model and the Power Wall use the exact same cell made by Panasonic model NCR18650B. The Panasonic NCR18650B cell is unquestionable the cream of the crop of NCO clls. No better NCO cell exist. As stated they cannot be shipped by plane and not many overseas shipping carriers will handle them because they are too dangrous. Now you know why Tesla wanted to build the Giga Factory. They will manufacture the cells under license and royalty agreements from Panasonic.
    Not correct, from Wikipedia
    "As of June 2012, the battery pack [Tesla Model S battery pack] used modified Panasonic cells with nickel-cobalt-aluminum cathodes.Each cell was of the 18650 form factor (i.e., an 18 mm diameter, 65 mm height cylinder), similar to the Panasonic NCR18650B cell that has an energy density of 265 Wh/kg."


    Without question A123 Systems make the best and longest lasting LFP cells. There is no better LFP battery on the market. Cycle life is 800 to 1200 cycles depending of DOD.
    You are only a factor of 10 out. From here


    My cheap Chinese Winston LFP prismatics have clocked up over 1,700 20% cycles over a period of nearly five years with little or no change in performance.

    Simon

    Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
    BMS - Homemade Battery logger github.com/simat/BatteryMonitor/wiki
    Latronics 4kW Inverter, homemade MPPT controller
    Off-Grid LFP(LiFePO4) system since April 2013

    Comment


    • #3
      Originally posted by karrak View Post
      FACT CHECK


      Not correct, from Wikipedia
      "As of June 2012, the battery pack [Tesla Model S battery pack] used modified Panasonic cells with nickel-cobalt-aluminum cathodes.Each cell was of the 18650 form factor (i.e., an 18 mm diameter, 65 mm height cylinder), similar to the Panasonic NCR18650B cell that has an energy density of 265 Wh/kg."
      You obviously did not look at the Spec Sheet. Tesla uses the NCR18650BE which is the latest version of NCR18650B. Only changes are 100 mah more energy (3400 mah) and slightly higher Specific Energy. You can buy the cells if you want for about $5 to $7 each. Sober up and go look for yourself. Same cell 500 cycles. The cells are the raw unprotected version. That is why they have two long paragraphs warning the buyer how dangerous the raw cells are.



      Originally posted by karrak View Post
      You are only a factor of 10 out. [/IMG2]
      No I did not. Did you actually look at the spec sheet I posted. Do you know the difference between a SPEC SHEET and a BLOG pumping hype? The whole purpose of the thread is to separate Fact from Fiction, and maybe save some folks a lot of money. I did not make it up, just FACTS. Your link is a BLOG made by unverified source......... You would have to be pretty stoned to believe 20,000 cycles. At 300 cycles per year would be 66 years. Who the heck do you think you are fooling with your fabrications? Have another snort or two.

      Here is your FACT CHECK. A123 SYSTEMS ANR26650M1B DATA SHEET. Count the cycles Karrak one at a time until you sober up 1, 2, 3, 4,5, 6, 7, 8, 9, 10 .... 1000. That is a Fact Check Jack. No go away and quit embarrassing yourself.

      Originally posted by karrak View Post
      My cheap Chinese Winston LFP prismatics have clocked up over 1,700 20% cycles over a period of nearly five years with little or no change in performance.
      There you go again. Your own charge/discharge graphs you have posted here many times is screaming at you the batteries are done. Problem is you do not know how to read charge/discharge graph. The Internal Resistance has tripled. You bought your own Chi-Com junk without any warranty or a clue. You are a pretender making things up.

      I knew you would take the rope and hang yourself with it.
      Last edited by Sunking; 01-19-2018, 06:39 PM.
      MSEE, PE

      Comment


      • #4
        Oh no, here we go again.

        Comment


        • #5
          Grab some popcorn and have a seat.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

          Comment


          • #6
            Originally posted by karrak View Post
            FACT CHECK


            Not correct, from Wikipedia
            "As of June 2012, the battery pack [Tesla Model S battery pack] used modified Panasonic cells with nickel-cobalt-aluminum cathodes.Each cell was of the 18650 form factor (i.e., an 18 mm diameter, 65 mm height cylinder), similar to the Panasonic NCR18650B cell that has an energy density of 265 Wh/kg."



            You are only a factor of 10 out. From here


            My cheap Chinese Winston LFP prismatics have clocked up over 1,700 20% cycles over a period of nearly five years with little or no change in performance.

            Simon

            Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
            BMS - Homemade Battery logger github.com/simat/BatteryMonitor/wiki
            Latronics 4kW Inverter, homemade MPPT controller
            After looking at/reading the text at the source of that chart, looks to me like it comes from something that's mostly advertising hype. I'd need a less biased and more authoritative/recognized source before I'd believe what that chart is showing.

            Such claims as made need something more serious behind them than advert hype, which is all that chart looks to be from.

            Hype is worth about as much as the fuel value of the paper it's printed on. Got anything from peer reviewed scientific/engineering literature that will take some serious scrutiny?

            Comment


            • #7
              Originally posted by Sunking View Post

              No I did not. Did you actually look at the spec sheet I posted. Do you know the difference between a SPEC SHEET and a BLOG pumping hype? The whole purpose of the thread is to separate Fact from Fiction, and maybe save some folks a lot of money. I did not make it up, just FACTS. Your link is a BLOG made by unverified source......... You would have to be pretty stoned to believe 20,000 cycles. At 300 cycles per year would be 66 years. Who the heck do you think you are fooling with your fabrications? Have another snort or two.
              For starters the blog I linked to is A123's official blog, just look at the URL.

              The number of cycles you get out of a battery is very dependent on the conditions you cycle them under. This is true for any battery, hammer an LA battery and you might get 100 cycles out of it, treat it gently and you might get 1,000 or more cycles, a tenfold increase. Exactly the same is true for lithium ion batteries. The >1,000 cycles figure in the A123 18650 spec sheet is at a discharge current of 5C!. This forum is all about offgrid and RV systems where the peak maximum discharge current will in most cases be less than 1C and definitely less than 2C and the average discharge current will be less than 0.1C. Under these circumstances you could expect up to 10,000 cycles. This is backed up by A123's own graph that I posted.

              There you go again. Your own charge/discharge graphs you have posted here many times is screaming at you the batteries are done. Problem is you do not know how to read charge/discharge graph. The Internal Resistance has tripled. You bought your own Chi-Com junk without any warranty or a clue. You are a pretender making things up.
              What you don't understand is that using the very oversimplified and inaccurate battery model that you use of just a voltage source in series with a resistor is that the value of the resistance is not constant and varies depending on the amount of current. You cannot infer from those graphs what the the resistance will be at a higher discharge rate like 0.6C.

              Just recently I measured the voltage drop of my whole battery under a ~0.6C load and got an impedance/resistance of ~5mOhms, this includes the resistance of the interconnectors. Guess what, the voltage drop was exactly the same when my battery was new nearly five years ago, so the impedance/resistance hasn't changed. This matches the data from these graphs, look at the lower right hand graph.
              LiIonstorage.jpg



              Simon

              Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
              BMS - Homemade Battery logger github.com/simat/BatteryMonitor/wiki
              Latronics 4kW Inverter, homemade MPPT controller
              Last edited by karrak; 01-21-2018, 12:47 AM.
              Off-Grid LFP(LiFePO4) system since April 2013

              Comment


              • #8
                Originally posted by karrak View Post
                What you don't understand is that using the very oversimplified and inaccurate battery model that you use of just a voltage source in series with a resistor is that the value of the resistance is not constant and varies depending on the amount of current. You cannot infer from those graphs what the the resistance will be at a higher discharge rate like 0.6C.
                I am not the one that does not understand. Resistance does not change with load current Temperature and Age yes, but not change with Discharge Rate. Simple physics. Heck you do not even know the difference between impedance and resistance.

                5 milli-ohms is an outright lie. You may not know it but any of us who know something about batteries know you are full of it and making it up. The resistance of your cell is just under 4 milli-ohms, and 4 in parallel is 1 milli-ohms` and 8 in series is 8 milli-ohms not counting connector and cable resistances which wil be about the same if properly designed. . Your are so BUSTED. Heck a Trojan T-105 has 3 milli-ohms at 6-volts with more than twice the capacity. At .6C (54 amps) as you claim across 4 mill-ohms is .216 volts for a single cell. At 8S is 1.7 volts or 9% voltage drop.

                Battery Internal Resistance is calculated using Delta Voltage / Delta Current. Since you are not an engineer and a pretender I don't expect you to know or understand anything especially Differential Calculus. Its above your pay grade and education level. Delta Voltage / Delta Current uses more than one plot, it use multiple points and in the case of a battery at low and high discharge rates. That makes it very accurate.
                Last edited by Sunking; 01-21-2018, 05:33 PM.
                MSEE, PE

                Comment


                • #9
                  Originally posted by karrak View Post
                  For starters the blog I linked to is A123's official blog, just look at the URL.
                  Are you that gullible? Look up right now at the ceiling.

























                  See the word "Gullible" printed on your ceiling?

                  I do not use Blogs, lies, or exaggerations. That is your thing. Do you think people are that stupid? In one hand I provide the manufacture spec for the exact same battery you are crowing about. Clearly states around 1000 cycles. Now you are gullible enough to print a BLOG that claims 20,000 cycles, and expect people to believe you?

                  That was the whole purpose of this thread is to separate "Fact from Fiction"
                  Last edited by Sunking; 01-21-2018, 02:44 PM.
                  MSEE, PE

                  Comment


                  • #10
                    Heh, and we're back to square one from years ago.

                    Sad that A123 posted that chart, even though they did mention that this was in lab conditions. Hey, didn't Prof. Jeffrey Dahn go through this already talking about doing repetitive "sausage factory" cycling and how that is not a reliable indication of cycle life?

                    At any rate, all the charts and so forth are good, but yet again, we are comparing apples-to-oranges leaving out the suitablity for our application. That is, high end motive-power / starting LFP, vs the lower performance standard LFP prismatics which are just fine for our solar power use. (when appropriately sized for current draw).

                    Much like comparing SLI lead-acid batteries to deep-cycle lead acid. The point being that yes, A123 LFP cylindricals are GREAT lfp, but that is total overkill for our solar application. Basically, if you were to build a bank out of these, you would be paying greatly for a capability you'll never use in your low-draw solar application.

                    Once again, we can prove cycles to ourselves if we want to rather cheaply. Heck, you don't even need to get prismatics for a simple test, but you can do some testing on a much smaller scale with relatively quality small cylindricals.

                    Huh? Grab 4 Tenergy (or other quality manufacturers NEW cells) 26650 size (about 3.3ah) cells and wire them up in series for a 12v battery. Use ones that have tabs on them. Or, put them into a "sled" if they have no tabs. If you have a small variable power supply, and know how to use it, then you can easily use the KISS method of individually charging each cell, and later charging as a pack and do your cycling with a small load. Use a 10 watt solar panel and a pwm controller with no temp comp. Know your load vs time, or use an inexpensive LVD. Powerwerx ITS-12 might be usable for that, which I use on the small stuff. Reminder - A123 capabilities would certainly be usable, but a waste of capability *for our application*.

                    Now you can run your own tests and prove it to yourself. But don't use it as a jumpstarter or motorcycle SLI battery. Leave that for A123 or other high-current cells. Use these off the shelf standard LFP cylindricals to emulate the lower end prismatics of the line. Ie, for our application, any high-end prismatics that manufacturers offer in their lines are once again a waste of capability and money for our application. Use a low-current load to last for 8 to 12 hours daily, and run your tests.

                    Prediction: You'll get bored with it, albeit getting in some good practice, and probably switch to the larger GBS, Calb, etc prismatics.

                    STILL, despite the chemistry, one has to do their power-budget homework, otherwise you are stuck with trying to get rid of an inappropriately sized bank, and nobody in their right mind should buy LFP used.
                    Last edited by PNjunction; 01-22-2018, 04:59 PM.

                    Comment


                    • #11
                      Originally posted by PNjunction View Post
                      At any rate, all the charts and so forth are good, but yet again, we are comparing apples-to-oranges leaving out the suitability for our application. That is, high end motive-power / starting LFP, vs the lower performance standard LFP prismatics which are just fine for our solar power use. (when appropriately sized for current draw).
                      Form Factor does not change anything. Jeffery and his group or any company who wants their battery tested requires a Button Battery the size of a watch or hearing aid battery. It has to be that way for their automated equipment. Motive power is not really high drain. Common sense should tell you that. When was the last time you seen an EV doing 350 mph to discharge its battery in 1 hour aka 1C-Rate? Tesla runs at C/7 top C/6 and the cells they use are not rated for high C-Rate application. At most at 2C if you floor it. Besides no EV manufacture would use LFP cells, their Energy Density sucks. As for charging if using for solar is going to be a higher charge rate than FLA because you can use a slightly smaller battery if you were to use LFP.

                      My whole epoint is lithium is not ready for home solar systems. They cannot compete with Pb in either price or cycle life. Last piece of critical thinking is if LFP did what some pretenders claim in terms of cycle life is ask yourself one simple question. Why won't they provide a warranty longer than 1-year vs 3, 5, 7, and 10 years for Pb? The Chi-Coms only offer a sharp stick in the eye for their prismatic cells.

                      As for lab test go. You are right not real life conditions. They are in pristine lab conditions using accelerated time compression to eliminate aging losses that cannot be duplicated in a lab. It takes time which LFP batteries have not passed that test or even been around long enough. PB has over 100 years of documented history. Buyer beware.
                      MSEE, PE

                      Comment


                      • #12
                        Originally posted by PNjunction View Post
                        Heh, and we're back to square one from years ago.
                        Not quite, we now have real data on a number of real LFP based off grid systems that are coming up to 5 years old and older.

                        Sad that A123 posted that chart, even though they did mention that this was in lab conditions. Hey, didn't Prof. Jeffrey Dahn go through this already talking about doing repetitive "sausage factory" cycling and how that is not a reliable indication of cycle life?

                        At any rate, all the charts and so forth are good, but yet again, we are comparing apples-to-oranges leaving out the suitablity for our application. That is, high end motive-power / starting LFP, vs the lower performance standard LFP prismatics which are just fine for our solar power use. (when appropriately sized for current draw).

                        Much like comparing SLI lead-acid batteries to deep-cycle lead acid. The point being that yes, A123 LFP cylindricals are GREAT lfp, but that is total overkill for our solar application. Basically, if you were to build a bank out of these, you would be paying greatly for a capability you'll never use in your low-draw solar application.
                        Couldn't agree more. If the tests are done with low charge and discharge rates they might give you an indication of what to expect in an off grid system.

                        The gold standard is data from real live off grid systems. My battery with its fairly easy life of only cycling around ~2.2kWh (~22% of its capacity through it each day) with a maximum discharge rate of ~0.6C and maximum charge rates of ~0.11C has little if any loss of capacity or performance over a five year period. On the other extreme is the off grid system built by Gordon who posts on the Energy Matters forum. His CALB 21kWh LFP battery gets down to 50%DOD in cool weather and 80%DOD in hot weather and lives in a hot tin shed. His system is used to run his house and a trout farm. On Sunday he used 50kWh of energy! His system is five years old and he thinks he has lost around 10% of the batteries initial capacity in that time. These are only two examples of many off grid systems based on 'cheap' Chinese LFP batteries that are all telling the same story.

                        Simon

                        Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
                        BMS - Homemade Battery logger github.com/simat/BatteryMonitor/wiki
                        Latronics 4kW Inverter, homemade MPPT controller
                        Last edited by karrak; 01-23-2018, 11:02 AM.
                        Off-Grid LFP(LiFePO4) system since April 2013

                        Comment


                        • #13
                          Originally posted by Sunking View Post
                          Besides no EV manufacture would use LFP cells, their Energy Density sucks.
                          Ever heard of BYD?

                          Why won't they provide a warranty longer than 1-year vs 3, 5, 7, and 10 years for Pb? The Chi-Coms only offer a sharp stick in the eye for their prismatic cells.
                          Probably because they are unsure what percentage of people who will use their batteries are idiots who will damage their batteries by abusing them. There are a number of suppliers of LFP batteries who offer warranties up to ten years. These batteries all have inbuilt BMSs or have to be used with a BMS to make sure that they are consumer proof.

                          As for lab test go. You are right not real life conditions. They are in pristine lab conditions using accelerated time compression to eliminate aging losses that cannot be duplicated in a lab. It takes time which LFP batteries have not passed that test or even been around long enough. PB has over 100 years of documented history. Buyer beware.
                          I wonder if the same was said when the horse was being replaced by steam engines, ICE and the electric motor. Heck the horse had only be around for thousands of years.
                          Last edited by karrak; 01-23-2018, 10:55 AM.
                          Off-Grid LFP(LiFePO4) system since April 2013

                          Comment


                          • #14
                            Originally posted by karrak View Post
                            Probably because they are unsure what percentage of people who will use their batteries are idiots who will damage their batteries by abusing them.
                            If so, are they more unsure than other battery providers of their customer's intelligence, or do they believe more idiots are buying their product ?
                            Last edited by J.P.M.; 01-23-2018, 12:27 PM.

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                            • #15
                              Karrak you should be a politician because you are a pathological liar. Proved it many times.your equipment because you got caught in a BOLD FACE LIE. In fact I caught you and hung you with your own rope in post 8.

                              Let me refresh your memory. you claim to have 32 x 90 AH Winston Thunder Turds arranged in 8S4P and measured 5 mili-oms internal resistance which is IMPOSSIBLE Look back at post 8 where I busted you.

                              5 milli-ohms is an outright lie. You may not know it but any of us who know something about batteries know you are full of it and making it up. The resistance of your cell is just under 4 milli-ohms, and 4 in parallel is 1 milli-ohms` and 8 in series is 8 milli-ohms not counting connector and cable resistances which will be about the same if properly designed. . Your are so BUSTED.
                              You have lied so much you cannot keep your own lies straight.
                              Last edited by Sunking; 01-23-2018, 03:24 PM.
                              MSEE, PE

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