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My Offgrid House & My Programable Solar BMS for any type of Lithium battery.

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  • My Offgrid House & My Programable Solar BMS for any type of Lithium battery.

    Deleted.

    To moderator please delete this treat see reasons at #81
    Last edited by electrodacus; 03-21-2014, 01:07 AM. Reason: Please delete this tread.

  • #2
    i'm off grid, and internet via android phone hotspot, so video is out.

    But your yellow box looks like a charge controller? Does it interface with individual BMS on each cell to provide proper balancing ? Or is there one box per cell ?

    Will this be getting UL rating, or will folks have to use it only in un-insured outbuildings ?

    The idea seems good, and it's a new, niche market that somebody has to start in.
    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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    • #3
      Originally posted by Mike90250 View Post
      i'm off grid, and internet via android phone hotspot, so video is out.

      But your yellow box looks like a charge controller? Does it interface with individual BMS on each cell to provide proper balancing ? Or is there one box per cell ?

      Will this be getting UL rating, or will folks have to use it only in un-insured outbuildings ?

      The idea seems good, and it's a new, niche market that somebody has to start in.
      I'm also offgrid with internet via android phone hotspot only 10GB/month and after that like is now just 256kb/s but I use a download add-on in Firefox so I can watch 144p not great but I have audio and good enough video to understand what is there
      Here is a image with a 3D render that i have done but the beta sample looks almost identical

      Is a charge controller with 40A charge and 80A discharge capabilities it has cell balancing there is a 10 pin connector that gets to each of the max 8 cell there are two ground pins out of those 10
      The balancing is passive and internal it can do up to 100mA/cell but that is more than enough since it can be programmed on how much time the balance is on.
      It will not be UL listed even if it can easily comply with since the main chip dose most of the magic the 32bit ARM microcontroller is there just to program the main chip, to display the measurement on the LCD and do data logging.
      It also have extremely low self power use only 25mW with the backlight OFF that is just 1mA with 8 cell 25V. With backlight on full is not much more 62mW
      I do not get why is this new since the lithium cells are safer and less expensive for energy storage.
      My LiFePO4 according to spec can get to about 20cent/kWh stored during lifetime that is a few times better that any Lead Acid that I know.
      They are inside no risk of hydrogen build-up.

      Comment


      • #4
        Originally posted by electrodacus View Post
        I do not get why is this new since the lithium cells are safer and less expensive for energy storage.
        My LiFePO4 according to spec can get to about 20cent/kWh stored during lifetime that is a few times better that any Lead Acid that I know.
        I would very much like to see the calculations behind that value, since it does not agree with what I have heard elsewhere, in terms of the comparison with Lead Acid.
        SunnyBoy 3000 US, 18 BP Solar 175B panels.

        Comment


        • #5
          Originally posted by electrodacus View Post
          I do not get why is this new since the lithium cells are safer and less expensive for energy storage.
          My LiFePO4 according to spec can get to about 20cent/kWh stored during lifetime that is a few times better that any Lead Acid that I know.
          They are inside no risk of hydrogen build-up.
          Put up data to back up your point! So far this is BS and stays that way until proven otherwise.

          1) Anyone claiming lithium is safer has to support that with data
          2) Anyone claiming lithium is cheaper has to support that with data
          3) H2 buildup is a bogeyman in about 99.99% of cases
          [SIGPIC][/SIGPIC]

          Comment


          • #6
            Originally posted by electrodacus View Post
            Is a charge controller with 40A charge and 80A discharge capabilities it has cell balancing there is a 10 pin connector that gets to each of the max 8 cell there are two ground pins out of those 10
            The balancing is passive and internal it can do up to 100mA/cell but that is more than enough since it can be programmed on how much time the balance is on.
            100 ma is all? Not very useful.

            Originally posted by electrodacus View Post
            I do not get why is this new since the lithium cells are safer and less expensive for energy storage.
            Who told you that? Lithium is currently 5 to 20 times higher than lead acid and why you do not see them in use.

            20 cent per Kwh my arse. Try 20 times more than that.
            MSEE, PE

            Comment


            • #7
              In another forum this was promoted as """-My-Programable-Solar-BMS-for-any-Lithium-cells-and-Supercapacitors """ ????
              As I said in that forum. That strip connector is really only good for about 20a at 24v. Its almost impossible to get good connections on cables thicker than #10. So cant see how it can be rated at 80a output capability.??

              Another little known problem with lifepo4 cells is the charge discharge parameters are actually different between under 20ahr and above. I dont think this controller can look after that problem..
              100ma is only good for cells below 20ahr. ie if cell 200 ahr it would take far to long to keep that cell below the cut off point and the others to "catch up". You need about 2a of balance capability on big(above 100ahr cells) Its one of reasons we discovered why car manufacturers are just about all using small cells.
              We have had a 100a 12,24,48v charger under development for 6 months . And its not as easy as it seems to get great results with all size cells.And if from different manufacturers it gets even harder.
              For very small systems of about 50ahr its hard to beat a Pwm charger that has adjustable voltage set point. But you also really need a dedicated LV load cut off switch. Something else the promoted charger does not seem to have..?????

              Comment


              • #8
                WoW so may questions.

                I will try to address all without the quotes since it will get messy.

                If I missed your question please ask again.


                1) I see most of you ask about the price of Lithium vs Lead Acid (I will be doing a more detailed video about this) but here is a short example.

                I have a 24Vbattery made out of 8 LiFePO4 cells 20Ah from A123 System each cell was 30$ including shipping and one cell has 3.2V x 20Ah = 64Wh so price is 30$/64Wh about 0.5$/Wh
                This price is not what you need to compare batteries or calculate cost / KWh stored during the lifetime of the battery
                According to A123 System spec sheet the battery can last for 3000 cycles with a DOD (depth of discharge) of 100% not only that but the battery still has 90% of the original capacity after that.
                I will not include charge discharge efficiency not to complicate things but is good for this battery over 95%

                So now the calculation one single cell 64Wh x 3000cycles x DOD100% = 192kWh during the lifetime of the cell
                Then 30$/192kWh = 0.156$ I rounded this number to 20cent since I'm conservative and used DOD or 80%

                Hope you are happy with the calculations.
                If you know a Lead Acid with better characteristics please show a similar calculation based on spec from reputable manufacturer.

                Then there is the bad charge discharge efficiency of the Lead Acid especially at higher charge discharge rate the fact that it needs to be vented or outside where low temperature in winter will affect this even more.
                Then there is Lithium-ion used now in most electric cars that start to find their way on the DIY market those have a lifestyle lower around 600 to 1000cycles used as car battery where weight is an important factor and they are charged to 4.2V to get the max capacity
                For solar weight is not important so you can charge them at 3.92V. By doing this the capacity will only be 60% of the stated one but the life-cycle will increase 8x and so making this 5x less expensive for storage than charged at 4.2V


                2) russ ask about the safety of Lithium vs Lead Acid.

                There are many types of Lithium chemistry and based on the level of safety you want you can chose one of them.
                Best in the safety category is what I use LiFePO4 it has worse energy density so is not used that much in mobile applications but is great for stationary energy storage.
                LiPO is the worst is probably what you see exploding or burning when overcharged or mechanically stressed.
                Lithium-ion the most common you probably have one in your phone and laptop and is the main choice for electric vehicle manufacturers do to is high energy density and good life cycle.
                Is not as easy to back this up with numbers unless I'm a chemist.
                As for Hydrogen released especially during charging on Lead Acid that is a fact you need ventilation to the outside or you need to have them outside not an option for me in middle of Canada with long and cold winters.

                3) 100mA is more than useful even for large battery banks of a few hundred Ah. The way it is implemented allows to program not just a voltage threshold but also a time that this balance current is on so if I set this to 10h it will discharge the higher cell with 1Ah but is not the case. I do manual balancing on my main battery bank for now and is no more than 200mAh between the cells after about two months of daily use.

                4) About the current capabilities of the SBMS4080

                First I used the best MOSFETs available cost was not my concern they have a typical RDSon of less than 2mohm each there are 4 in parallel on discharge that is under 0.5mohm the current shunt is also just 0.25mohm so a total of under 4.8W in heat will be dissipated at full 80A discharge.
                Second the connectors have a spec of 20A each for Battery connection I use 4 and for discharge 4 the other two are for charge as you seen a total of 10 and are only used for the positive lead the negative is common and connected outside.

                5) There are over 30 parameters that can be programmed see the table that I attached.

                Hope this answerer most questions please ask anything else. I'm an electrical engineer a good one I like to think and a good person.

                Comment


                • #9
                  Thank you for providing such specific answers. Links to your sources would also be helpful.

                  As I know basically nothing about the relative merits of different battery technologies, I'm not qualified to evaluate your claims.

                  However, I think you will observe that some of the people on this forum are very conservative about adopting new technologies, and will want to see several years of experience with this in the field before they believe your cost and performance claims. I think this is understandable, given that putting in a new system can be a 20-30 year commitment.
                  16x TenK 410W modules + 14x TenK 500W inverters

                  Comment


                  • #10
                    Originally posted by pleppik View Post
                    However, I think you will observe that some of the people on this forum are very conservative about adopting new technologies, and will want to see several years of experience with this in the field before they believe your cost and performance claims. I think this is understandable, given that putting in a new system can be a 20-30 year commitment.
                    Not to mention that 90% plus of such things go down the toilet for any number of reasons
                    [SIGPIC][/SIGPIC]

                    Comment


                    • #11
                      You are in fantasy land saying LFP has 3000 cycles. More like 300 to 600 cycles.
                      MSEE, PE

                      Comment


                      • #12
                        Originally posted by pleppik View Post
                        Thank you for providing such specific answers. Links to your sources would also be helpful.

                        As I know basically nothing about the relative merits of different battery technologies, I'm not qualified to evaluate your claims.

                        However, I think you will observe that some of the people on this forum are very conservative about adopting new technologies, and will want to see several years of experience with this in the field before they believe your cost and performance claims. I think this is understandable, given that putting in a new system can be a 20-30 year commitment.

                        By links to my sources are you referring to the A123 System 20Ah LiFePO4 datasheet ? If so then here is a link
                        http://www.raceyard.de/tl_files/News...Data-Sheet.pdf
                        There are well done tests on this battery and other batteries that I have on my youtube channel
                        https://www.youtube.com/user/electrodacus

                        Well Solar panels have more than 20 to 30 years on the field already and at the current cost of under 1$/watt they are extremely affordable at my location they get down to under 3cent/kWh if I consider 25year of service life that is the reason I will buy more solar panels and heat my house directly with solar PV no battery involved Energy will be stored in the form of heat in my thermally insulated slab about 100kWh of capacity at a delta of 10 degree Celsius.
                        Energy storage in battery is still expensive at 20cent/kWh but not that much that is problem for an offgrid house.
                        I purchased all my solar equipment including batteries for about the same money I will have paid on the least expensive connection to the grid.
                        I lived in an apartment before and power consumption was a bit high tere about 250kWh/month for that the bill was exactly 50$ so 20cent/kWh if you include taxes and everything.
                        Now I use around 60 to 100kWh/month offgrid at an equivalent cost of around 30cent/kWh most of that is the battery but is acceptable for me since I did not pay for the connection fee to the grid that alone will have been more than the cost of equipment.

                        I do not see any reason at the moment for anyone to disconnect from the grid an use battery to store energy but if you build a new house with no option to grid or expensive to connect then solar is a good alternative.

                        As for the SBMS4080 that I build is not that expensive at around 160$ US including shipping and it can protect batteries worth at least an order of magnitude more.
                        It can also be used for other applications like solar bicycles, scooters, UPS, power tools or anywhere a Lithium battery is needed up to 8 cell or Supercapacitors but those will be even a more debated topic.

                        Comment


                        • #13
                          Originally posted by Sunking View Post
                          You are in fantasy land saying LFP has 3000 cycles. More like 300 to 600 cycles.
                          Check the replay above this with the link to the A123 System datasheet. Or you do not trust A123 System to provide accurate informations?

                          Comment


                          • #14
                            Originally posted by electrodacus View Post
                            Or you do not trust A123 System to provide accurate informations?
                            A123 does not exist. No third party data long term testing to back up claims. At best LFP is a 500 to 1500 cycle product that is available today. Granted I think LFP wil be improved, still not ready nor any cost advantage. That is why you do not see any for RE applications.
                            MSEE, PE

                            Comment


                            • #15
                              Originally posted by Sunking View Post
                              A123 does not exist. No third party data long term testing to back up claims. At best LFP is a 500 to 1500 cycle product that is available today. Granted I think LFP wil be improved, still not ready nor any cost advantage. That is why you do not see any for RE applications.
                              How is not A123 System an existing company. How then I got my A123 System cells made in USA and from my tests they are exactly as specified except for the life cycle that will require me to destroy at least one cell and a few months of testing at 1C charge discharge rate.
                              Then what about the proven Lithium-ion they are from much larger companies I even seen some Nissan Leaf batteries at better price than the A123.
                              And what about the 3.9V instead of 4.2V charging of the Lithium-ion that increases the life cycle 8x while reducing the capacity with only 40%

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