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

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  • #31
    Originally posted by cracovian View Post
    It would be a shame to drop $5K on solar backup inverter stuff and then kill them quickly with my daily cycling.

    EDIT: Xantrex finally shut down after going through 1.69 kWh with the battery pack down to 10.9 volts. I'm charging it back at 2 amps now.
    Assuming they are using LiFePO4 cells which I think is likely, as long as you keep the cell voltages in the range 3.45V-3.10V/cell (13.8V-12.4V,~100%-20%SOC) under load or when being charged you should get good use out of them. LFP batteries are happy being deep cycled.

    The nominal energy storage of each of your 12V batteries is ~2.35kWh (13.08*180). So you got about 72% (1.69/2.35) of the rated capacity out of the battery. You said on your first post that the batteries were all reading 13.37V. If the batteries had been sitting without any use for a long period of time this voltage should equate to a battery over 90% full. If the 1.69kWh from the Xantrex is the output power you will have to add the inverter losses, might be as high as 15%-20% because of the low power draw.

    10.9V shutdown is fine, corresponds to ~2.7V/cell (10.9/4). Discharging at 100W (~.05C, 100*180/13.08) and cutting out at 10.9 would mean you would have somewhere around 5% left in the battery.

    Charging at 2A is going to take 90 hours to charge the battery.

    Simon

    Off-Grid LFP(LiFePO4) system since April 2013

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    • #32
      This is great, karrak - love the numbers and your analysis.

      I increased the charging amps and I'm back in business. I used the meter and the cells show 3.70, 3.60, 3.70, 3.70 (14.70 V) on that 1st of 8 packs now.

      I bought and I'm waiting for one of those cheap 3 in 1 RC testers/balancers for up to 6 cells.

      While they're good at detection and monitoring, will they actually balance my large packs when necessary? If not, how can I balance individual packs "manually" if I don't come up with anything more real-time and automatic?

      Also, I used the cheap(er) Schneider charger (designed for lead tech with 2,10,15 amp options) and it seems to be charging fine but did it go too high? Is is safe to use for now?

      EDIT: I've posted a photo of 1 of 4 without the case (held by duct tape, of course) and another 1 of 4 still in the case (front panel removed) that still has the BMS cables hooked up along with its plug. Aside from serial numbers and BYD Auto tags, there are no other markings on these batteries but they sure look tough and heavy
      Attached Files
      Last edited by cracovian; 08-22-2016, 07:44 PM.
      10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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      • #33
        Originally posted by cracovian View Post
        I increased the charging amps and I'm back in business. I used the meter and the cells show 3.70, 3.60, 3.70, 3.70 (14.70 V) on that 1st of 8 packs now.
        If the batteries are LFP those voltages are too high. You should keep the charge voltage below 3.6V/cell.

        Were those voltage at the end of charge? What have the voltages dropped back to a while after the charger was disconnected from the battery?

        I bought and I'm waiting for one of those cheap 3 in 1 RC testers/balancers for up to 6 cells.

        While they're good at detection and monitoring, will they actually balance my large packs when necessary? If not, how can I balance individual packs "manually" if I don't come up with anything more real-time and automatic?
        They might be able to keep the battery in balance, but will be unable or have difficulty getting the battery into balance due to the small balance current that they are capable of passing. Can you provide details of what devices you have bought.

        You can balance with a 1 ohm 5W power resistor. I will give you more details later. I am in a bit of a hurry.

        Also, I used the cheap(er) Schneider charger (designed for lead tech with 2,10,15 amp options) and it seems to be charging fine but did it go too high? Is is safe to use for now?
        It is not safe charging with this charger!! The charge voltage is too high. For long life you should limit the charge voltage to 3.45v/Cell ( 13.8V). I wouldn't do any more charging until you have someway to monitor the individual cell voltages while you are charging. If any of the batteries are out of balance the voltage of an individual cell can rise very quickly (within minutes) and damage that cell.


        EDIT: I've posted a photo of 1 of 4 without the case (held by duct tape, of course) and another 1 of 4 still in the case (front panel removed) that still has the BMS cables hooked up along with its plug. Aside from serial numbers and BYD Auto tags, there are no other markings on these batteries but they sure look tough and heavy
        Can you get any photos of the BMS circuit board. From the voltage you gave above it looks like that battery is in balance.

        Simon
        Last edited by karrak; 08-22-2016, 09:06 PM. Reason: Added info about not charging without cell monitoring
        Off-Grid LFP(LiFePO4) system since April 2013

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        • #34
          Keep following instructions from the internet and hooking up chargers at random is going to get you a visit from the battery police (aka Fire Department)

          Be very careful and double check informations from the internet, Never know who is on the other end

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          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

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          • #35
            Thanks, Mike! I PMed you my home address, so you can come over and explain/hook up my batteries in person

            Or are you really Mike... and not that Mika who just hooked up with Joe?
            10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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            • #36
              Originally posted by Mike90250 View Post
              Keep following instructions from the internet and hooking up chargers at random is going to get you a visit from the battery police (aka Fire Department)

              Be very careful and double check informations from the internet, Never know who is on the other end

              [ATTACH=CONFIG]n327358[/ATTACH]
              The more I deal with people, the more I like dogs.

              Sometimes the elegance of simplicity is not obvious, but a picture is indeed sometimes worth a thousand words. WOOF !

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              • #37
                As financially-unreasonable when it comes to solar, EVs, and green energy as I am, I'm still debating if AC-coupling is really worth it (in my case, with free batteries, and the Flexpower Outback set.)

                What I think I could do for now is hook the batteries up in the 48V configuration and use the 48V Delta-Q charger (I also have a 72V version) that I have to charge the batteries with the some kind of (manual) remote trigger when it's sunny and solar is overabundant.

                I would love to be able to trickle charge my LEAF (up to 1.44 kW at 120 volts) overnight but that requires a 48 Volt inverter and those are quite pricy and don't seem to be reliable from the reviews I've seen. Any recommendations?

                I could also get another higher current 12V Xantrex but then I would need to switch the batteries from the 48V combination to all parallel every time I charge the car.

                Also, any simple and cheaper way to unload the energy into my electrical panel at night once they're charged with Delta-Q?

                What does everyone think?
                Last edited by cracovian; 08-24-2016, 03:58 PM.
                10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                • #38
                  Originally posted by cracovian View Post
                  What does everyone think?
                  Since you ask, IMO only, it reads to me like you're a bit obsessed, but I'm not a shrink.

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                  • #39
                    Originally posted by cracovian View Post
                    I would love to be able to trickle charge my LEAF (up to 1.44 kW at 120 volts) overnight but that requires a 48 Volt inverter and those are quite pricy and don't seem to be reliable from the reviews I've seen. Any recommendations?
                    Really not a job for any Inverter to have a heavy continuous load on them, like a battery charger. Not exactly what the designers had in mind. Anyway you are looking in the wrong place for good 48 volt rectifiers. Look in the Salvage Telecom market. There you will find Industrial grade 48 volt Inverters up to 1 to 5 Kw.and beyond.

                    Last edited by Sunking; 08-24-2016, 04:04 PM.
                    MSEE, PE

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                    • #40
                      Originally posted by J.P.M. View Post

                      Since you ask, IMO only, it reads to me like you're a bit obsessed, but I'm not a shrink.
                      Why do you have to go personal, man? I have the free (quite decent) batts sitting in my garage, I have tons of solar, bad net metering, TOU, and I have an EV.

                      I could drop $5K to save a few cents but it doesn't make too much sense for on-grid.

                      If you have a problem then GTFO or I can too.
                      10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                      • #41
                        Originally posted by J.P.M. View Post

                        Since you ask, IMO only, it reads to me like you're a bit obsessed, but I'm not a shrink.
                        Belittle much?

                        Thanks for all of your help, btw. Very useful.
                        10 x LG300 ACe, 24 x M250 (9.84 kW DC)

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                        • #42
                          Originally posted by cracovian View Post

                          Belittle much?

                          Thanks for all of your help, btw. Very useful.
                          We try. Ya' like our service - tell your friends.

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                          • #43
                            Originally posted by cracovian View Post

                            Why do you have to go personal, man? I have the free (quite decent) batts sitting in my garage, I have tons of solar, bad net metering, TOU, and I have an EV.

                            I could drop $5K to save a few cents but it doesn't make too much sense for on-grid.

                            If you have a problem then GTFO or I can too.
                            Yet you want to cheat the POCO out of a few cents by illegally using your batteries to charge your EV.

                            If you have the money to purchase solar and and EV then go with a grid tie system and do it safely and legally. Just forget about the stupid batteries before you get hurt.

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                            • #44
                              Originally posted by SunEagle View Post
                              Yet you want to cheat the POCO out of a few cents by illegally using your batteries to charge your EV.
                              I don't think that's cheating OR illegal, provided the power does not go through the grid on its way to the EV. (It's also not the most efficient use of a PV array, but it's his money to waste.)

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                              • #45
                                Originally posted by cracovian View Post

                                Why do you have to go personal, man? I have the free (quite decent) batts sitting in my garage, I have tons of solar, bad net metering, TOU, and I have an EV.

                                I could drop $5K to save a few cents but it doesn't make too much sense for on-grid.

                                If you have a problem then GTFO or I can too.
                                It was joke. See the font ? But on a serious note, if I pose a question such as "What does everyone think ? ", I wouldn't bitch about the responses I got, as much as I'd be careful what I ask for.

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