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  • Battery Comparison for 48V off grid system

    Hi all, I was wondering if someone could help me with a watt hour calculation on these two proposed sets of batteries:

    Original proposed set up was 16 Fullriver DC400-6 AGM Sealed 6V 415Ah Batteries. Two stings of 8 for the set up.

    Optional proposed set up is using Simpliphi PHI 3.4 48V battey. As I understand it 3 total.

    I have a good general understanding of the differences in the battery chemistry and different DOD recommendation for each type. What I'm having a hard time calculating with any level of confidence is the usable capacity of both set ups. If someone can point me in the right direction to figure that out I'd appreciate it.

    Any other comments or recommendations are always welcome.


    Reference links to the two batteries:
    https://www.wholesalesolar.com/cms/f...4017212128.pdf
    http://simpliphipower.com/product/phi-3-4-battery/


    Thank you!
    Last edited by Mike90250; 01-12-2018, 11:05 PM. Reason: removed icon

  • #2
    Well this sis easy peazy and a slam dunk.

    Capacity of any battery is Voltage x AH = Watt Hours

    So the AGM is 48 volts x 830 AH = 39,840 watt hours or 39.8 kWh

    The other is a rip off you should stay far away from. 24 volts x 134 AH = 3216 watt hours or 3.2 kWh. You cannot use 3 of them at 24 volts, only in groups of two. You would have to have 10 of the batteries to equal the AGM.

    No contest.
    MSEE, PE

    Comment


    • #3
      Hey Sunking, thanks for the response! That was a pretty easy calculation!

      On the Simplifi battery we were looking at the 48V version. Their specifications section shows the 48V with 67 AH and 3440 Watt Hours - which I guess the real # is 3216 Watt hours based off the calculation you provided. If I had three of those in series is that as simple as 3 x 3216 = 9648 watt hours?

      If so the AGM's at 50% DOD would give me a usable 19,920 watt hours which is still slightly more than double with taking the Simplifi batteries to 100% DOD.....

      Am I even close???
      Last edited by cgofish; 01-10-2018, 10:50 PM.

      Comment


      • #4
        In addition to the Simplifi, another LiFePO4 possibility is with the new Discover 48 V 6.6 kWhr Canbus capable batteries with integral BMS (Top balancing ???). They are designed to report S.O.C. to Schneider Conext and SMA systems and auto generator start which provides added levels of operating convenience and safety. They also provide battery monitors that link to the Canbus that display SOC.

        I have no idea if they are more economically attractive than the Simpli Phi but from what I have seen so far Discover is an impressive company, and they are local to us here in BC!

        I'm still leaning towards old tech 24 times 2 V tubular FLA cells (with a simple wave powered flapper valve column off the dock as an airlift pump for anti-acid stratification ??) for our island home's 48 V battery bank / XW system. We are also pondering FLA vs AGM vs LiFePO4, but perhaps things are changing faster than we all realize ....

        42-48-6650 Advanced Energy System Battery Specifications:

        http://discoveraes.com/wp-content/up...-44-Series.pdf

        Case Study:

        http://discoveraes.com/wp-content/up...eti-Island.pdf

        Anyone else familiar with these new batteries?

        - Solarislanders

        Comment


        • #5
          Originally posted by cgofish View Post
          Hey Sunking, thanks for the response! That was a pretty easy calculation!

          On the Simplifi battery we were looking at the 48V version. Their specifications section shows the 48V with 67 AH and 3440 Watt Hours - which I guess the real # is 3216 Watt hours based off the calculation you provided. If I had three of those in series is that as simple as 3 x 3216 = 9648 watt hours?

          If so the AGM's at 50% DOD would give me a usable 19,920 watt hours which is still slightly more than double with taking the Simplifi batteries to 100% DOD.....

          Am I even close???
          On the right track, just going the wrong direction. First you would not install the Simplifi LFP battery blocks in series as that would be roughly 150 volts. They would have to be wired in parallel. Just one catch, you would not want to install them in parallel. You would only be able to use one of them.

          Next in line is with AGM you can discharge them deeper than FLA batteries. You can take them down as far as 80% DOD which is exactly what a LFP battery can do. But you should never allow that to happen with either battery. You want to limit discharge to 20 to 30% per day on any battery type.

          As for the error you discovered in capacity, the Simplifi nominal battery voltage is slightly higher than the AGM lead acid. Lead Acid nominal is 48 volts and the LFP is 51ish volts. Try that and you get the 3440 wh. You are correct the watt hours add so if you had 3 x 3216 = 9648 wh.

          None of the above is all that important. What is important is what you wallet thinks as it is the boss of everything. Your wallet would fire you if you used the LFP battery. Both the AGM and LFP have roughly the same cycle life and usable capacity, and here is what your wallet wants to know. Your wallet demands to know what is the $/wh cost. To figure that out take the cost of one unit, and calculate the $/wh cost. With just a quick search 1 unit of the Full River 6-volt 415 AH battery cost $510 each and yields 2490 watt hours. So $510/2490 = $ 0.20 - wh. I also found the 48 volt 3440 wh Simplifi 48 volt 67 AH unit for $3675, so $3675 / 3400 wh = $1.08-wh.
          Now I do not know what your wallet would say about that, but mine says you would be a damn fool to buy the LFP battery paying 500% more. What does your wallet say about that? It is a No-Brainer decision when you know the facts. Let your wallet do your thinking and not the piece of meat between your ears or legs.

          Do I have your attention yet? If so what about using say a Rolls S-550 a FLA 6-volt 428 AH battery. Unit cost is roughly $335. Here is why you should consider them, your wallet. Here is the deal the AGM and LFP battery warranty is 2 years. The Rolls is 7-years which means they should last at least 3 times longer. If you do the life cycle calculations using 25% DOD per day, the wh delivered cost of AGM is 400% higher than FLA, and LFP is 1200% higher than FLA. What does your wallet say about that?

          Look AGM has applications in solar, but you need to justify the higher cost. To do that requires 1 of the following conditions to be met:
          • Extreme cold environment of -40 degrees. At those temps eliminate LFP period.
          • Unusual mounting orientation like on their side.
          • Spills cannot be tolerated like on an aircraft which is why AGM was invented.
          • Very high charge and discharge rates.


          Last edited by Sunking; 01-12-2018, 01:07 PM.
          MSEE, PE

          Comment


          • #6
            Originally posted by Sunking View Post
            First you would not install the Simplifi LFP battery blocks in series as that would be roughly 150 volts. They would have to be wired in parallel. Just one catch, you would not want to install them in parallel. You would only be able to use one of them.
            Not correct, from the Simpliphi installation manual
            "PHI SMART-TECH BATTERIES ARE DESIGNED FOR PARALLEL OPERATION ONLY - DO NOT ARRANGE IN SERIES FOR INCREASED VOLTAGE"

            Next in line is with AGM you can discharge them deeper than FLA batteries. You can take them down as far as 80% DOD which is exactly what a LFP battery can do. But you should never allow that to happen with either battery. You want to limit discharge to 20 to 30% per day on any battery type.
            True for FLA batteries for long life, for LFP batteries 20%-30% cycles will give over 10,000 cycles, in an off-grid system this could be more than 30 years! I think it it would be better to run 50%-60% cycles on LFP batteries which will probably still give you around 20 years of life.

            Both the AGM and LFP have roughly the same cycle life and usable capacity,..
            Not correct, the Fullriver AGM brochure linked to by the OP give 1500 cycles @40%DOD, from the Simpliphi warranty you get 5000 cycles @100%DOD

            Here is the deal the AGM and LFP battery warranty is 2 years.
            Fullriver provide a 2 year replacement warranty and 7 year pro rata warranty. Simpliphi give a 10 year pro rata warranty.

            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


            • #7
              Originally posted by karrak View Post
              Not correct, from the Simpliphi installation manual
              "PHI SMART-TECH BATTERIES ARE DESIGNED FOR PARALLEL OPERATION ONLY - DO NOT ARRANGE IN SERIES FOR INCREASED VOLTAGE"
              I never said you cannot parallel them, I said you WOULD NOT WANT to parallel them. Big difference. If you parallel any modular battery (more than 1-cell in series), does not matter what type, you are going to significantly shorten cycle life. Proven fact Jack.


              Originally posted by karrak View Post
              True for FLA batteries for long life, for LFP batteries 20%-30% cycles will give over 10,000 cycles, in an off-grid system this could be more than 30 years! I think it it would be better to run 50%-60% cycles on LFP batteries which will probably still give you around 20 years of life.
              There is not one single LFP battery or any battery with 10,000 cycles in existence.

              20 - 30 year battery. 50 -60% cycles. Now that is some funny stuff, I don't care who you are. One cloudy day and you go dark.

              [Moderator note - removed irrelevant content]
              Last edited by sensij; 01-13-2018, 12:46 PM.
              MSEE, PE

              Comment


              • #8
                Originally posted by Sunking View Post
                I never said you cannot parallel them, I said you WOULD NOT WANT to parallel them. Big difference. If you parallel any modular battery (more than 1-cell in series), does not matter what type, you are going to significantly shorten cycle life. Proven fact Jack.
                I have started a new thread looking at this topic.

                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


                • #9
                  Originally posted by karrak View Post
                  I have started a new thread looking at this topic.

                  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
                  You must like getting beat up.

                  MSEE, PE

                  Comment


                  • #10
                    This is Harold.
                    I am designing my own solar system right now and will use either the 9.5 kwh LG Chem Li-ion battery or the Pika energy island with 10.5 kwh.
                    To me those batteries have the longest warranty and the most discharge charge cycles.
                    I have 14 panels Panasonic or LG.
                    What are the expert thinking about this ???
                    Greetings, Harold

                    Comment


                    • #11
                      Originally posted by hbrand View Post
                      This is Harold.
                      I am designing my own solar system right now and will use either the 9.5 kwh LG Chem Li-ion battery or the Pika energy island with 10.5 kwh.
                      To me those batteries have the longest warranty and the most discharge charge cycles.
                      I have 14 panels Panasonic or LG.
                      What are the expert thinking about this ???
                      Greetings, Harold
                      What are your loads ? (itemized in watt hours, please)
                      Last edited by Mike90250; 01-14-2018, 09:31 PM.
                      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

                      Comment


                      • #12
                        Originally posted by Mike90250 View Post

                        What are your loads ? (itemized in watt hours, please)
                        Average monthly use is 390KWH

                        Comment


                        • #13
                          Originally posted by hbrand View Post
                          I am designing my own solar system right now and will use either the 9.5 kwh LG Chem Li-ion battery or the Pika energy island with 10.5 kwh.
                          To me those batteries have the longest warranty and the most discharge charge cycles.
                          I have 14 panels Panasonic or LG.
                          What are the expert thinking about this ???
                          Greetings, Harold
                          First you are hijacking someone else thread.

                          To start with there is no such thing as 9.5 kWh of panels. I assume you mean 9500 watts of solar panels aka 9.5 Kw based on 14 Panasonic or LG panels. 9500 watts on a off-grid battery system is a huge system that is going to require two very expensive 80 amp charge controllers operating into a 48 volt battery. 24 volts 4 controllers and 12 volts if you are a fool will be 8 controllers.

                          Selecting Lithium batteries is the exact opposite of what you asked for. The longest warranty and cycles are Flooded Lead Acid batteries at 1/3 the cost.

                          Lastly there is this..

                          Average monthly use is 390KWH
                          That would mean you use 390 kWh / 30 days = 13 Kwh each day. That is an insane amount of power for a battery system. To do that with FLA batteries requires a $13,000, 4000 pound battery you will be replacing every 5 years. Use LFP and you are looking at a $18,000, 2000 pound battery you replace every 3 to 4 years.

                          MSEE, PE

                          Comment


                          • #14
                            Originally posted by Sunking View Post
                            To start with there is no such thing as 9.5 kWh of panels. I assume you mean 9500 watts of solar panels aka 9.5 Kw based on 14 Panasonic or LG panels. 9500 watts on a off-grid battery system is a huge system that is going to require two very expensive 80 amp charge controllers operating into a 48 volt battery. 24 volts 4 controllers and 12 volts if you are a fool will be 8 controllers.
                            As usual you are not reading what the OP said. The OP said he has 14 panels (probably around 300W ea) and was looking at at the 9.5kWh LG battery or the 10.5kWh Panasonic battery


                            That would mean you use 390 kWh / 30 days = 13 Kwh each day. That is an insane amount of power for a battery system. To do that with FLA batteries requires a $13,000, 4000 pound battery you will be replacing every 5 years. Use LFP and you are looking at a $18,000, 2000 pound battery you replace every 3 to 4 years.
                            Please explain how steveg manages to use about the same amount of power each day with his LFP battery based off grid system as the OP intends to and that it nearly 8 years old? This post gives details about his system and its 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


                            • #15
                              Originally posted by karrak View Post
                              As usual you are not reading what the OP said. The OP said he has 14 panels (probably around 300W ea) and was looking at at the 9.5kWh LG battery or the 10.5kWh Panasonic battery




                              Please explain how steveg manages to use about the same amount of power each day with his LFP battery based off grid system as the OP intends to and that it nearly 8 years old? This post gives details about his system and its 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
                              While some people may be able to generate power for a long time and get many cycles out of their batteries, I would say it is only a small % that will ever reach an 8 year life span with their batteries.

                              On top of that it is easy to make a statement in an open forum without needing to provide the facts to back it up.

                              I am not saying you or "steveg" are not telling the truth but a number of people come here and do like to embellish the "facts".

                              Comment

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