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Lead Acid vs Lithium Iron Phosphate ( LFP; LiFePO4 )

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  • #16
    @sunking - yes I tend to agree ... I think you can buy some from OEM excess in the US also, but then a good BMS is needed...

    Altair nano also make a great technology - once again OEM/military only product.

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    • #17
      Expensive bms

      Have any of the people making all the endless statements that you need expensive BMS for LFP batteries ever actually obtained a few cells set them up with a simple solar charger and a simple BMS and seen what happens??? Or you all just go on making statements that you have never verified ???

      Have you all investigated the fact you dont have to buy ANY external BMS for some made up batteries at all ,as the BMS is built into the battery pack so you just connect them up and use them in a way very similar to how you would use lead acid batteries.

      Sure for cars using the batteries its a big issue as the very high charge and discharge rates

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      • #18
        Hi John,

        you are probably right for low current cycles, my BMS is for overcharge/over discharge cutout - it has some levelling but very weak circa 1A.

        It was also basically free with the battery pack - large format 100Ah cells for my home.

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        • #19
          Originally posted by steveg View Post
          - my 15kWh system was US$7000 ...
          Well yes you can get 15 Kwh for that buying a China Copy Cat LFP from Thundersky, but you are not going to get anywhere near the performance of a quality A123 System LFP. You may get 1000 cycles, maybe a bit more, but no where near the 10,000 cycles A123 Systems is guaranteeing.
          MSEE, PE

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          • #20
            @Sunking - yes but ...

            1) I am not cycling the batteries anywhere near 80% per day (every day)
            2) They are not Thundersky cells, Seiden Brand.
            3) Completely agree about A123 cells being *far* superior in cycles
            4) I will get 1500 cycles at 80% DOD as per manuf data with a guarantee

            At the end of that 1500 CyclesI will have 80% of the capacity left they arent a throwaway ... just less capacity

            1500/365.25 = 4 years assuming a 80% discharge every day, which is not the case - also aging of the cells I factored capacity degrade over 5 years regardless 20-30% ... so I have 7-9kWh capacity life after 5 years by my calc - of course I will have to run the experiment to see if I am right.

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            • #21
              Steve like I said I think in the very near future LFP will make its mark on the Renewable Energy sector and I fully support it. However I design the systems and the economics are not there yet to sell them. Most of my clients are very very large telephone companies, and when we build a remote cellular site, they demand a 10 year battery with 6 to 10 day reserve capacity period. I cannot make the dollars work out to go with Lithium.

              In a home system it is getting close, certainly much closer than say just 1 year ago. But using the inexpensive copy cat LFP batteries, we are looking at 50-cents per watt hour compared to 14 cents for a top of the line 10 year Surrette battery.

              So as an example using the LFP we can cut the reserve capacity from 5 days to 3 days to equal the same equivalent as a FLA battery of 2.5 days real reserve capacity. So keeping the math simple basing 1 Kwh per day in a LFP battery you need a 3 Kwh capacity, and 5 for FLA. So the initial cost are straight forward. LFP = $.50 x 3000 wh = $1500 vs FLA = $.14 x 5000 wh = $700. So as you can see the LFP is still 100% more than FLA. But here is the real kicker for me and my clients that inexpensive copy cat LFP does not come from a reputable manufacture with a rock solid warranty and will need replaced in about 5 years. I can spec the Surrette with a 10 year warranty and it will last 10 years.

              I know the comparison is not apples to apples comparison as I used the cheapest LFP battery against the best FLA battery. If I had used something like A123 Systems and the numbers would be staggering at 6 times the cost for the same 10 year life cycle

              So until that economy changes with LFP, IMO FLA will rule the RE markets.
              MSEE, PE

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              • #22
                Certainly - if you need warranties for Telco installs then the numbers dont stack up vs the risk - but for folks like me who are doing their own system it makes perfect sense.

                All I can say is my LFP was *LESS* than the 1040Ah 10yr warranty PbA that I started looking at 12kNZD vs 20kNZD ... 835NZD 1040Ah 2V cell 835*24=20k

                Local reputable dealer.
                http://www.aasolar.co.nz/Price-List.html#batteries

                My 300Ah pack is equal (close enough) to this in terms of usable day to day power (30%DOD for PbA) - yes you can run out your PbA 1000Ah but my calculations mean that I increase my PV rack to cope - on the darkest day we have had in winter I get 2->3kWh into my system, panels run at around 10% of their rated value peak on those days.

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                • #23
                  Oh yes - sorry forgot to add - this is AGM and not FLA, but it seems they were not readily available when I did my research.

                  I worked through - NiFe, PbA, NiMh then LFP then back to NiFe with extra panels to cope with the terrible charge efficiency (65%) then decided that if I had enough panels then you dont need so much in 'reserve' so a LFP pack worked our the best bang for my buck.

                  I can always add a wind gen - and I do have a generator

                  Anyway I have made my technical choice and I am happy to answer questions on how it is working out.

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                  • #24
                    Originally posted by john p View Post
                    .... Have you all investigated the fact you dont have to buy ANY external BMS for some made up batteries at all ,as the BMS is built into the battery pack so you just connect them up and use them in a way very similar to how you would use lead acid batteries......

                    Got any vendors for that ?? I'm looking at replaceing a 48V 400A Pb battery bank by the end of next summer (it currently manages to run a fridge all night).

                    And what fails first, the intergal BMS, or the cells ? Which ever fails, the wife will not like it with no lights.
                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

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                    • #25
                      Hi Mike,

                      How many kWh for that?

                      say it's 5kWh ...

                      5000/51.2=98Ah at 70% DOD that's 140Ah LFP pack - I would recommend talking to this guy - mention Steve from New Zealand.

                      Chris Zhang [sales02@chinabatterycenter.com]

                      Should be US$2300 (+FGT+TAX) roughly for 100Ah 48V(16 cell) with a BMS built in.

                      I have 48 of these cells in my setup.

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                      • #26
                        MIKE90250 here is the Australian website but I believe they also have an American manufacturing plant and dealers ,,, The batteries are made up in 12,24,48 and 144v I think.. they just look like normal big deepcycle batteries
                        http://lithbattoz.com.au/?page=about-us

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                        • #27
                          John which model number? I know of this company.
                          MSEE, PE

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                          • #28
                            Sunking and others .. the web site has changed(not for the better) and now just shows one batch of manufactured batteries.and very little detailed info .. But I remember they were available in 12v 24v and 48v even 144v But dont know the present position ..

                            I have never used one of there complete batteries only the individual cells. Ive used 160 of then for almost 3 years(read my other posts on this thread) no problems so far.. But did destroy a sample one in one day by discharging it down to 2 volts..I now warn everybody never go below 2.5v. As no warranty if you damage it that way.. Ifound they are harmless even thoug been told some bad things about them ,, I cut my dead one open with a hacksaw on the kitchen table.. it survived ok.

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                            • #29
                              Ok John was just curios as I am familiar with them as I checked them out when upgrading my golf cart. However I am not aware of any of their packs with built in BMS. Not saying they do not offer one, I just do not know of one with them.

                              What i do know about them is they tailor their product line to the Electric Vehicle industry. So all of their products i know about are high current charge and discharge rates and require an external BMS
                              MSEE, PE

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                              • #30
                                Sunking if you look at the website it shows a picture of one of the batteries that just loOks like a normal 12v battery.. they really do have the BMS built in I have seen one opened up it was a 48v one,, The BMS circuit board sits on top of the cells with "regulators" to each cell..

                                They make 2 ranges of batteries one range more suitable as starting batteries the other more suitable as"storage" "

                                THEY SELL TO ANYONE WITH MONEY..

                                You are welcome to spend money in Australia.

                                aS I said I bought seperate cells just in case one fails. As they installed in the Philippines.. easier to replace one defective cell than try bring back a complete 20kg battery..

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