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(8x12) 96V 180 Ah BYD lithium pack... Any useful applications?

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  • #76
    Originally posted by SunEagle View Post

    Ok. Now I am confused. If you had micros-inverters and a grid tie system all along how did you figure on using them to charge those batteries?

    Most of the Hybrid solar systems use the DC from the panels to either go to the grid tie inverter or to the battery charger. Then the software/hardware allows you to either use the grid or the batteries if the grid is down.
    As I suspected, read, and as a few experts explained earlier in the thread, an AC-coupled Outback inverter/charger ($2,500 - $6,000) can on its own use AC power from the main (timed, sensed, or triggered manually over internet during high solar output) and charge batteries accordingly. Cheaper SonnenBaterie compact systems coming this November will also have this capability out of the box where grid power is required to be present for any of this to work.

    I'm not really looking for a backup and isolating critical loads, only daily and regular cycling to even out my peaks and valleys while reducing costs of buying power back. All I'd like to do is to reroute some of my solar overproduction from the main to the 10 kWh+ batteries and releasing it back (replacing or supplementing power from the grid) to the main at close enough and specified rates to be consumed in real time (usually at night, peak TOU, or when charging my EV.)

    The main reason is that my net metering sucks, pays 4 cents/kWh, while what I buy costs me anywhere between 12 and 30 cents.

    EDIT: El cheapo idea I had was to plug into the 120 V outlet and remotely trigger my existing 48V Delta-Q charger to charge the battery bank in the 48 V configuration. An inverter of some kind is then needed to release that energy later, therefore, the discussion around the Chinese grid tied inverters and much more expensive AIMS that are nice on paper but unreliable with only 1-year warranty.
    Last edited by cracovian; 08-26-2016, 08:29 PM.
    10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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    • #77
      Originally posted by cracovian View Post

      As I suspected, read, and as a few experts explained earlier in the thread, an AC-coupled Outback inverter/charger can on its own use AC power from the main (timed, sensed, or triggered manually over internet during high solar output) and charge batteries accordingly. Cheaper SonnenBaterie compact systems coming this November will also have this capability out of the box where grid power is required to be present for any of this to work.

      I'm not really looking for a backup and isolating critical loads, only daily and regular cycling to even out my peaks and valleys. All I'd like to do is to reroute some of my solar overproduction from the main to the 10 kWh+ batteries and releasing it back (replacing or supplementing power from the grid) to the main at close enough and specified rates to be consumed in real time (usually at night, peak TOU, or when charging my EV.)

      The main reason is that my net metering sucks, pays 4 cents/kWh, while what I buy costs me anywhere between 12 and 30 cents.
      Ah. I understand better. And with free batteries I would also want to find a way to use them to capture excess power generated then to sell it for a few cents. Still it sometimes takes spending a few thousand to save a few hundred. Seems lopsided.

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      • #78
        So with Powerwall 2.0 that is $6,500 installed, has 14 kWh capacity, massive 5 kW (7 kW peak) output from the built-in inverter, does it mean there are no other viable options to look at now? This seems so ideal it's not even funny (crying for Sonnen, Enphase, and even Outback now just a little...)

        My only question would be whether it can be installed on my AC side of things to work with AC microinverter strings. Any insight into that?
        10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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        • #79
          Originally posted by cracovian View Post
          So with Powerwall 2.0 that is $6,500 installed, has 14 kWh capacity, massive 5 kW (7 kW peak) output from the built-in inverter, does it mean there are no other viable options to look at now? This seems so ideal it's not even funny (crying for Sonnen, Enphase, and even Outback now just a little...)

          My only question would be whether it can be installed on my AC side of things to work with AC microinverter strings. Any insight into that?
          Too soon to tell how the Powerwall 2.0 will work in a home with a micro-inverter pv system. The ink is still not dry yet on documents.

          IMO the new Powerwall 2.0 is nothing but more advertising hype by Tesla to gain additional capital for the Solar Power purchase.

          More than likely the battery system is still many months away from being a real commodity for purchase. Sure it will be beta tested but for anyone to just go purchase one will probably not happen until after 2017.

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          • #80
            Originally posted by cracovian View Post
            So with Powerwall 2.0 that is $6,500 installed, has 14 kWh capacity, massive 5 kW (7 kW peak) output from the built-in inverter, does it mean there are no other viable options to look at now?
            Installed does not equal installed.... By that I mean IF $6.5k is the installed price of the powerwall 2, that would be for a minimal install that does not do backup.

            To do backup you would need an auto transformer, disconnect, and a lot more wiring and labor to create the emergency panel.
            OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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            • #81
              The creature is alive! I've hooked up 4 packs (~7-8 kWh) in series for 48V so far and installed two outlets (along with wifi outlet adapters) on separate breakers for safe charging/discharging. One is connected to the QuiQ charger (1-1.2 kW but still trying to pick the best algorithm) and the other one to the 22-60V 87% efficient "grid tie microinverter" that feeds power back at 500-600W which is about the base load of my house. I put the Foscam there too, so I can see the voltage monitor and look around the setup I have down there. With Georgia Power paying only 3.5 cents/kWh now, I can divert some of my solar (10 KW AC) and use it at night when needed. Very cool.

              Attached Files
              10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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              • #82
                Great to see that you are using these batteries. I am wondering if you are monitoring the individual cell voltages?

                Simon

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

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                • #83
                  Hi Simon! I'm using your earlier responses as my battery voltage bible and will try to stay within the 50-55 Volt band for the entire pack.

                  Individual cells were all within .1 Volts to begin with but the TB6-B charger is getting delivered today and I will charge/top off each of the 32 cells individually with its LiFePO4 profile over the next few days.

                  I might check them from time to time but how often should I really? Also, I noticed that when the pack is getting full during charging, the voltage will read over 60 Volts but when disconnected from the charger, it drops into the high 50s right away. Is this normal? What's the absolute max during charging? And, no, not really planning to go that high ever again once the other 4 are connected for extra capacity. I'm just wondering about that spread and how wide it normally is or should be.
                  Last edited by cracovian; 02-09-2017, 09:37 AM.
                  10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                  • #84
                    Originally posted by cracovian View Post
                    Individual cells were all within .1 Volts to begin with but the TB6-B charger is getting delivered today and I will charge/top off each of the 32 cells individually with its LiFePO4 profile over the next few days.
                    Are you going to do each cell individually or in groups of 4 or 6?

                    I might check them from time to time but how often should I really? Also, I noticed that when the pack is getting full during charging, the voltage will read over 60 Volts but when disconnected from the charger, it drops into the high 50s right away. Is this normal? What's the absolute max during charging?
                    60 Volts is too high!, it corresponds to 3.75V/cell. The maximum voltage you should take any cell to is 3.65V/cell (58.4V). For long life you shouldn't charge to more than 3.5V/cell (56.0V) and preferably 3.45V/cell (55.2V) and let the current taper off to C/20-C/50 (C equals the battery capacity in Ah) When you have finished charging you should drop to a float voltage of around 3.35V/cell (53.6V). If you charge to 60V I would expect the voltage to drop rapidly and then more slowly to around the mid 50 volts.

                    The time to check the balance is at the end of charging. I would do it every charge until you are confident on how the balance varies and then less frequently.

                    And, no, not really planning to go that high ever again once the other 4 are connected for extra capacity. I'm just wondering about that spread and how wide it normally is or should be.
                    I am not to sure what you mean here?

                    Just so I have got things straight, you are currently using the QuiQ charger to charge the 48V battery? Which model have you got and is this what you will be using in the long run?

                    Simon

                    Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
                    BMS - Homemade Battery logger github.com/simat/BatteryMonitor
                    Latronics 4kW Inverter, homemade MPPT controller
                    Last edited by karrak; 02-09-2017, 10:38 AM.
                    Off-Grid LFP(LiFePO4) system since April 2013

                    Comment


                    • #85
                      Originally posted by cracovian View Post
                      Hi Simon! I'm using your earlier responses as my battery voltage bible and will try to stay within the 50-55 Volt band for the entire pack.

                      Individual cells were all within .1 Volts to begin with but the TB6-B charger is getting delivered today and I will charge/top off each of the 32 cells individually with its LiFePO4 profile over the next few days.

                      I might check them from time to time but how often should I really? Also, I noticed that when the pack is getting full during charging, the voltage will read over 60 Volts but when disconnected from the charger, it drops into the high 50s right away. Is this normal? What's the absolute max during charging? And, no, not really planning to go that high ever again once the other 4 are connected for extra capacity. I'm just wondering about that spread and how wide it normally is or should be.
                      DANGER DANGER ( Thank you again Karrak for guiding another neophyte into FIRE LAND )

                      You should be doing the engineering planning BEFORE you connect the batteries, not wondering why "over 60" and then "50s" when the system is Live.
                      Do you have a BMS that monitors each cell, or have you Top or Bottom Balanced each cell individually. Note that charging each cell individually is going to remove any Top or Bottom Balance you have done,

                      Sadly Cracovian, I am not an expert in Li batteries. I AM an electronics engineer, and live off grid with a NiFe battery bank, Any advice you receive from Karrak is likely to be flawed as he is not a scientist or a battery professional.. ( and he's going to Banned Land shortly when I finish here )

                      I advise you to solicit the harsh advice of Sunking (who, like anyone, makes typos) and to read about your specific flavor of Li battery in the Battery university, to determine voltage setpoints, to get your gear set up properly before it burns up. About a week ago, I saw a burned bank of 3 packs of Li batteries used off grid, and the owner wanted me to advise how to do it right, and I've refused, it's over my head to be able to "do it all".


                      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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                      • #86
                        Crac what make and model LFP battery are you using? I am to lazy to back track 3 pages.
                        MSEE, PE

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                        • #87
                          They're older BYD auto batteries that were (lightly) used in a corporate battery backup system a couple of years ago. BYD has used LiFePO4, so I can only assume that's what it is. There are no other specific markings.

                          I "saved" them from recycling for free, so I'm not sweating too much. I can drain almost 2 kWh out of each pack (16 kWh in total), so trickling 500W each night will allow me to keep them in that 50-55 Volt band.

                          Karrak has been very helpful, not making useless jokes like others, and his advice has been in line with the recently-posted LiFePO4 sticky in another section, I can only speak to that and I'm not sure what you're talking about ban-wise.
                          10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                          • #88
                            Originally posted by cracovian View Post
                            I might check them from time to time but how often should I really? Also, I noticed that when the pack is getting full during charging, the voltage will read over 60 Volts but when disconnected from the charger, it drops into the high 50s right away. Is this normal? What's the absolute max during charging? .
                            Not sure how to answer this because you have not confirmed the battery type. What I will say is if they are in fact LFP you should never charge higher than 57.6 volts, but I would never recommend a voltage that high. To charge LFP to 100 % requires 3.6 volts per cell, but you should never charge to 100%.

                            I do not know what your charger is capable of doing. Having said that back the voltage off to 55.2 volts or 3.45 volts per cell and let them float. That will give you roughly 90% SOC and maximise battery life. Never let the pack voltage dip below 48 volts or any cell to dip below 2.6 volts.

                            Are you monitoring cell voltages or pack voltage?

                            To answer your question if you charged to 60 volts you were playing with Russian Roulette with a loaded gun. Yes the voltage would drop from 60 volts down to around 57.6 volts quickly. 60 volts was to high and eventually would likely start a fire. With any Lithium battery you want to stay away from the knee curves at the top and bottom. If you look at charge/discharge curves for LFP batteries those knees occur at 2.9 and 3.5 volts. So you run them at 3 to 3.45 volts.
                            Last edited by Sunking; 02-09-2017, 11:58 AM.
                            MSEE, PE

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                            • #89
                              Thanks for your help, Sunking! I'm monitoring the entire pack but I'm planning to check on individual cells occasionally.

                              I just added 4 kWh this morning and while charging, the displayed voltage read 56.32 V. Based on your advice I turned it off and it read 54.31 V two minutes later and it keeps dropping ever more slightly - down to 54.24 now and settling. That's over 2 Volts (.125 per cell) of difference right away, so is this normal? Which number should I be concerned about?
                              10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                              • #90
                                What you are seeing is normal for any battery type. Again I am not sure what battery type you really have. If it is LFP and you were seeing 56.32 volts corresponds to 3.52 volts per cell which is still OK but to high for my comfort.

                                Here is the deal. LFP batteries are compatible with Lead Acid battery chargers. Unfortunately the same mentality is used to charge LFP. What I mean is the industry uses a Pb mentality to charge LFP batteries to 100% SOC. There is no reason to do that with LFP batteries. With lead acid batteries (Pb) you must charge them to 100% and hold them at 100% to maximise the battery life. However doing that with LFP batteries (charge them to 100%) shortens the cycle life. Additionally charging LFP batteries to 100% requires Vampire Boards aka BMS. What the Vampire Boards do is Turn On when a cell reaches 100% SOC and bleed it so it does not charge anymore while lower cells catch up and waits for all Vampire Boards to turn on and terminate the charge. There is no need to do all that. In fact the Vampire Boards are the leading cause of LFP battery failures. There is no reason to do that.

                                If you were to look at say Genasun Charge Controllers made for all Lithium battery types, are very simple Float Chargers. You have to specify what type of Lithium Battery you are using. For LFP take note of the voltage they use. It is 14.2 volts or 3.55 volts, not 14.4 or 3.6 volts per cell for 100%. You can also specify a lower voltage when you order them. The logic they are using is to stop short of 100% SOC, and then hold or FLOAT.. Example let's say your battery pack reaches 14.2 volts at noon. The batteries saturate and stop charging. From that point going forward any power you demand comes from the panels, and not the battery. The battery is saved until it gets dark. If you used the industry mentality you would charge to 3.6 volts, and have to terminate the charger. If that happens by noon, you are on battery power the rest of the day not utilizing solar power. All that does is wear out your battery faster cutting cycle life in half.

                                EV manufactures do not fall into that trap. They will not allow you to fully charge or discharge the batteries. Most EV's only charge the battery up to 90% and cutoff at 10%. Others like Telsa do not even go that high and low. It is the only way they can offer such long warranties.

                                Once LFP batteries are balanced, they do not go out of balance much as long as there is no parasitic loads. My racing golf cart is going on 8 months and is still balanced. Once I detect imbalance I will take action. Many DIY EV builders do not use a BMS and getting much longer battery life than those who do use BMS and charge to 100%.

                                So try this. Set your charger to 55.2 volts and let it charge the batteries until charge current STOPS. Then measure the voltage of each battery. As long as they read no lower than 3.4 or higher than 3.5 volts you are good. If not balance the batteries.
                                MSEE, PE

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