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Does my MPPT SCC and 120V charger choice make sense for my LiFeMnPO4 batteries?

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  • #16
    FWIW I had a minute so i just took a look and the Victron Connect 2.3 software on my laptop that interacts with the 75/15 controller does allow a time limit to be set for the absorption stage if needed, in 1 minute increments 0 to 12:00 hours. The software also has a nice 30 day history that is pretty complete including lots of harvest stats and how much time spent each day in all 3 stages, error codes reported (if any), etc.

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    • #17
      Originally posted by LETitROLL View Post
      FWIW I had a minute so i just took a look and the Victron Connect 2.3 software on my laptop that interacts with the 75/15 controller does allow a time limit to be set for the absorption stage if needed, in 1 minute increments 0 to 12:00 hours. The software also has a nice 30 day history that is pretty complete including lots of harvest stats and how much time spent each day in all 3 stages, error codes reported (if any), etc.
      OK let's KISS it. Keep It Simple Stupid.

      If in fact you can set Absorb time from 0 minutes to 12 hours gives you some options to work with and be comfortable. Charging LFP batteries is super simple. Anyway here are 2 good options to consider with your GBS batteries.

      1. Set Bulk/Absorb to 13.8 volts, and FLOAT to 13.6 volts. Set Absorb time to 30 minutes initially. This method is going to require you to observe charge current for a week or so. What is going on is your Controller will stay into Constant Current phase until the battery voltage reaches about 13.8 volts, then at that point is Constant Voltage or Absorb stage begins. The charge current will start to taper off as the batteries Saturate to 13.8 volts. Ideally you would want to Terminate Absorb when the current tapers to 5% of C. Example if the cells are rated 100 AH, then 5 amps. Well your Solar Charger does not do that, it uses time. So what you have to play with it to find that amount of time it takes until you see the current taper down to around 5%. Don't sweat bullets trying to nail 5%, just do not let it go to 0 amps which would be 100% charged, you want to avoid that. Using this method gets to to mid/high 90's% SOC which is pushing your luck a bit. Once the timer times out the voltage switches to a lower FLOAT voltage of 13.6 volts and your batteries FLOAT while your panels supply power to loads until sunset.

      2. Is my favorite because it is the no fuss or worry method. Just set Bulk/Absorb to 13.8 volts, ZERO minutes Absorb, and Float to 13.6 volts. Works exactly like above, except as soon as the Controller detects the charge current starts to Taper Off will lower the voltage to 13.6 volts and the batteries will Float. Like above the panels will provide power to the loads until sunset.

      The difference between the two options is option 1 gets to to mid/high 90% SOC and option 2 gets you to high 80, low 90's% SOC. Option 1 does come with some risk if and when the batteries ever become unbalanced. So be on the lookout for any one cell going to 3.6 volts. Ideally you want them at 3.45 floating.

      Now I must warn you so pay attention. You have to perform an Initial Bulk Balance of the cells before putting them into service. When they arrive they will be around 40 to 60% SOC. Here is the problem. If say have one cell at 60% SOC and one down around 40%, you can easily destroy the cell with 60% SOC on the very first charge cycle. If will be charged up well before the lower cells. That is why you keep an eye on individual cell voltages and be on the lookout for one going to 3.6 volts before all the others. At the end of a charge cycle you want to see no cell lower than 3.4 volts and no cell above 3.5 volts. They should all be around 3.45 volts ideally.

      So you are going to have to figure out how to Balance them when they arrive. You start by connecting them all in Parallel and walk away over night. At that point they are Midle Balanced and fairly well balanced, but there are two more options of Top and Bottom Balanced. So do your homework and figure out what you are going to do.
      Last edited by Sunking; 03-12-2017, 05:02 PM.
      MSEE, PE

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      • #18
        and no BMS needed correct? just keep cells in the proper range, after initial balancing, and check them from time to time for balance? Have a LVD set to make sure they dont get run down too far.

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        • #19
          Originally posted by LETitROLL View Post
          and no BMS needed correct? just keep cells in the proper range, after initial balancing, and check them from time to time for balance? Have a LVD set to make sure they dont get run down too far.
          Not for a 4S system. Lithium batteries do not go out of balance like other types. They age and lose capacity, so you have to keep an eye on them. They just need to be balanced initially.

          Yep set your Inverter up to shut down at 12 volts or 3 volts per cell. LFP batteries are drained at 2.5 volts. and if they go below 2 volts they will be damaged. Well hell with 4S that is 8 volts. If the Inverter is set to trip ar 12 volts is a heck of a lot of cushion. At 3.0 volts is roughly 10% SOC and at 4S is 12 volts. Even if the Inverter LVD is set to 10.5 volts is OK.

          When you get up to 16S and beyond is when you at least want some cell monitoring.
          MSEE, PE

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          • #20
            Originally posted by LETitROLL View Post
            FWIW I had a minute so i just took a look and the Victron Connect 2.3 software on my laptop that interacts with the 75/15 controller does allow a time limit to be set for the absorption stage if needed, in 1 minute increments 0 to 12:00 hours. The software also has a nice 30 day history that is pretty complete including lots of harvest stats and how much time spent each day in all 3 stages, error codes reported (if any), etc.
            That is great to know, thank you! I see no reason to buy a more expensive charge controller.

            And SunKing, thanks again for the recommendations. You did a great job explaining what happens under each of the scenarios, so I will probably try option 1 as a learning exercise but have option 2 in my back pocket as well.

            I will be using a BMS, seems like a cheap insurance policy in case something else goes awry. It will have low voltage cutoff, high voltage cutout and top-end shunt-type cell balancing. I will be able to see the voltage of each of the 4 cells, so my plan is to watch it when I charge it and if there is a large cell inbalance I will stop and do a bottom balance. Bottom balancing looks really straight-forward, I am just not sure how I would do it without spending $280 on a CellPro Powerlab 8 (which seems to be how everyone does it.)

            Shot of the GBS battery BMS display (on the cell voltage screen):


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            • #21
              Pitfalls of attaching a BMS
              1) it's got lots of parts, usually made as cheap as possible in China, and seldom has proper engineering behind it. More parts, wires, connections = more ways things can go wrong on you
              2) top end shunt. Unless the shunt can bypass your charger entire current ( a 30A charger needs 30A shunts) you still have a very high chance of cooking a cell or three, If you have 30A charger, and your BMS has 2 A shunts, your "full" cells will only be overcharged by 28A instead of a 30A overcharge, Big Whoopee, so what, You need at least a 25A shunt, and then you only cook your cell with 5A. Still going to kill the cell.

              In solar applications, high charging current is needed to replace the consumed power in the short 3 or 5 hour solar day. you are not going to trickle charge the battery with 5 amps.
              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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              • #22
                Originally posted by ASprinter View Post

                That is great to know, thank you! I see no reason to buy a more expensive charge controller.

                And SunKing, thanks again for the recommendations. You did a great job explaining what happens under each of the scenarios, so I will probably try option 1 as a learning exercise but have option 2 in my back pocket as well.

                I will be using a BMS, seems like a cheap insurance policy in case something else goes awry. It will have low voltage cutoff, high voltage cutout and top-end shunt-type cell balancing. I will be able to see the voltage of each of the 4 cells, so my plan is to watch it when I charge it and if there is a large cell inbalance I will stop and do a bottom balance. Bottom balancing looks really straight-forward, I am just not sure how I would do it without spending $280 on a CellPro Powerlab 8 (which seems to be how everyone does it.)
                OK you got me confused. Is this a 12 volt battery?

                Why am I seeing 12 cells? I should only see 4 Cells.

                Even if your configuration is 4S3P I should only see 4 cell voltages.

                Anyway I do Bottom Balance as do most folks who customize EV and Golf Carts. But here is the deal, you cannot use the BMS to perform your Initial Bulk Balance. A BMS is designed to only keep a Top Balanced pack in Balance, thus very small minor corrections. The reason is the Vampire Boards aka Balance Boards can only bleed a very small current. Not sure what your boards are rate dat but typical is 300 to 500 Milli-amps. New batteries will have a significant difference. 10 to 20 AH difference depending on capacity of the cell. With Solar only have a average 4 Sun Hours it can take days or weeks. A 500 milli-amp board can only correct up to 2 AH per day, and if the th ecell range difference is 20 AH you are talking 10 days.

                I do have a Cell Pro 8 and a few others. Great charger to have. Not only will it do Lithium, but any battery chemistry on the face of earth today and tomorrow in the future. To Top Balance you would also need a DC Power Supply to go with that Cell Pro. Bottom Balance you do not need a DC Supply because you will only discharge and not charge.

                I can get you started. If you Top, Bottom or Mid Balance you connect all cells in Parallel to start with.

                If you Mid Balance you just walk away over night. Next day install them in series. Use Option 1 or 2.

                Bottom Balance after you walk away for the night, then discharge them so at rest the finale voltage falls no higher than 2.5 volts, and no lower than 2.4 volts. Connect them is series and charge until one cell reaches 3.55 volts then terminate the charge. Note charge voltage and use that as you rset point using option 1 as the high point. Float will still be 13.6 volts.

                If you go with Top Balance, you need to build a Balance Plug for the Cell Pro. After leaving them in parallel over night, install them with your Balance Plug you made for the Cell Pro. assuming a 12 volt configuration set the charger up for LiFe 4S. Charge at as high of a rate as youR DC Power Supply will let you go assuming you do not go over the Cell Pro limit which I think is 50-Amps off the top of my head. Terminate when the current tapers off to 3% of C. So if the total capacity is 100 AH, terminate at 3 amps.

                If you go with Top Balance let me know because you wilL want to use your BMS to disconnect the batteries if any cell drops to 2.6 to 2.9 volts under load. Use option 1 or 2 to charge.
                MSEE, PE

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                • #23
                  Mike,
                  I appreciate the insight on use of BMS. I am purchasing the batteries as a kit that also includes the BMS, vampire boards, two contactors and the shunt-based battery monitor with the LCD display. I like the idea of having the BMS as a backup to perform the LV and HV cutout in the event some other part of my system fails. I know there are other ways to do it, but I think this is a good way for a newbie like myself to go.

                  Originally posted by Sunking View Post

                  OK you got me confused. Is this a 12 volt battery?
                  Sorry for the confusion, yes, there will only be 4 cells. The 12-cell pic above is simply a photo I stole off the internet.

                  Anyway I do Bottom Balance as do most folks who customize EV and Golf Carts. But here is the deal, you cannot use the BMS to perform your Initial Bulk Balance. A BMS is designed to only keep a Top Balanced pack in Balance, thus very small minor corrections. The reason is the Vampire Boards aka Balance Boards can only bleed a very small current. Not sure what your boards are rate dat but typical is 300 to 500 Milli-amps. New batteries will have a significant difference. 10 to 20 AH difference depending on capacity of the cell. With Solar only have a average 4 Sun Hours it can take days or weeks. A 500 milli-amp board can only correct up to 2 AH per day, and if the th ecell range difference is 20 AH you are talking 10 days.
                  You are correct, the BMS applies a 0.5A load when cell voltage hits 3.55V to cell balance. I suspect doing a cell balance before putting this into use will be critical because with the charge settings being recommended to me it sounds like the cells are unlikely to hit the 3.55v required to initiate cell balancing.

                  I do have a Cell Pro 8 and a few others. Great charger to have. Not only will it do Lithium, but any battery chemistry on the face of earth today and tomorrow in the future. To Top Balance you would also need a DC Power Supply to go with that Cell Pro. Bottom Balance you do not need a DC Supply because you will only discharge and not charge.

                  I can get you started. If you Top, Bottom or Mid Balance you connect all cells in Parallel to start with.

                  If you Mid Balance you just walk away over night. Next day install them in series. Use Option 1 or 2.

                  Bottom Balance after you walk away for the night, then discharge them so at rest the finale voltage falls no higher than 2.5 volts, and no lower than 2.4 volts. Connect them is series and charge until one cell reaches 3.55 volts then terminate the charge. Note charge voltage and use that as you rset point using option 1 as the high point. Float will still be 13.6 volts.

                  If you go with Top Balance, you need to build a Balance Plug for the Cell Pro. After leaving them in parallel over night, install them with your Balance Plug you made for the Cell Pro. assuming a 12 volt configuration set the charger up for LiFe 4S. Charge at as high of a rate as youR DC Power Supply will let you go assuming you do not go over the Cell Pro limit which I think is 50-Amps off the top of my head. Terminate when the current tapers off to 3% of C. So if the total capacity is 100 AH, terminate at 3 amps.

                  If you go with Top Balance let me know because you wilL want to use your BMS to disconnect the batteries if any cell drops to 2.6 to 2.9 volts under load. Use option 1 or 2 to charge.
                  I would likely do a bottom balance. If I have to buy equipment (CellPro 8) at least I don't also have to buy a DC power supply.

                  Comment


                  • #24
                    Originally posted by ASprinter View Post
                    Sorry for the confusion, yes, there will only be 4 cells. The 12-cell pic above is simply a photo I stole off the internet.
                    THX. I knew something was not right.

                    Originally posted by ASprinter View Post
                    You are correct, the BMS applies a 0.5A load when cell voltage hits 3.55V to cell balance. I suspect doing a cell balance before putting this into use will be critical because with the charge settings being recommended to me it sounds like the cells are unlikely to hit the 3.55v required to initiate cell balancing.
                    You are correct, before the Vampire Boards turn on, they must reach the trigger point. To use the BMS would require you to set the Controller to 14.4 volts or 4 x 3.6 volts per cell. At 13.6 to 13.8 no cell should get high enough to trigger them on if they are BALANCED. So keep your eyes on the cell voltages near the top and bottom. Look for the one higher than the others at the TOP, or a cell with lower voltage at the BOTTOM. The spread from high to low should be no greater than 0.1 volts at the top or bottom. In the middle should be less than .05. They should always be between 3 and 3,45 volts.

                    But back to Mike's point and what DIY EV builders have experienced is two fold failures. If you have say a 20 amp charger, and the By Pass boards can only shunt .5 amps, when the first cell triggers it is very possible charge current will still be 20 amps or at least more than the shunt can bypass leaving the remainder still flowing through a fully charged cell. Once that cell reaches 4.2 volts you go into thermal run-away. Now in theory that should not happen if the cells are balanced to start with will reach 3.6 volts at roughly the same time.

                    However it takes a special charger to work with the bypass boards. It needs a signal to tell the charger the first By Pass Board has turned on, and then the controller cuts back charge current to .5 amps. Understand?

                    But the real problem with Bypass Boards with monitors have a nasty failure mode and parasitic loads. Bypass boards have a nasty habit of failing shorted. That means they never unlatch and keep BLEEDING .5 amps. Unless you are on top of your game, you will not catch it until it over discharges a cell. Lithium batteries do not tolerate being over discharged. The stronger cells will eat the bad cell by reverse polarity and destroys the cel instantly making a dead Short Circuit. That is when the Magic Smoke escapes followed by spewing gel and flames.



                    Originally posted by ASprinter View Post
                    I would likely do a bottom balance. If I have to buy equipment (CellPro 8) at least I don't also have to buy a DC power supply.
                    Well you do not need the Cell Pro to do that. You just need a load to discharge the cells. There is a catch though. You had better be there to catch the moment when the voltage drops to 2.5 volts. Once it goes below 2.0 volts is death. With the Cell Pro you can program it to stop discharging at any voltage you want automatically. You start by setting it to say 10 amps discharge and stop at 2.5 volts. First time around the cell voltage will rebound up above 2.5 volts. You keep lowering the current. What I do is set the voltage to 2.4 volts. Your goal is after rested no cell above 2.5 volts or lower than 2.4 volts. Takes a while. Once you get there that is 0 AH capacity at 10 volt pack voltage. Set your LVD to 12 volts. At 12 volts you stil have around 10% capacity left in the tank.

                    With Lithium Batteries STAY AWAY FROM THE KNEE CURVES at both TOP and BOTTOM. Makes no difference what point you balance at, Top, Bottom, or Middle. Stay away from fully charged and discharged.
                    Last edited by Sunking; 03-13-2017, 05:42 PM.
                    MSEE, PE

                    Comment


                    • #25
                      If you were designing the electrical system for a recreational vehicle with a LiFeMnPO4 battery, how would you do it? You are really helping me understand how all of the various components work together, however without a BMS how would you devise an automatic LV/HV cutoff in case the inverters and chargers didn't do it on their own? I want that second line of defense but I'm unsure how to get there without the BMS.

                      I'm not sure how the top-end cell balance works on my Nissan Leaf, but I know the canbus tells my charger to reduce charging amperage significantly once the battery hits near 100% and cell balancing initiates. (That takes 40 min after the battery hits 100%.) The BMS that comes with my GBS batteries obviously isn't that sophisticated.

                      Comment


                      • #26
                        OK let's get one thing straight, I am NOT telling you cannot use a BMS. OK?

                        I am saying it is not required. As Mike points out most system you can buy are Chi-Com and quality is questionable. What I am saying is with a 4S battery or 12 volts it is blatantly obvious if a cell voltage goes out of whack. With LFP you are most concerned with over discharge.

                        Let's use a Bible tactic, a parable. Peter, A DIY EV uses a 45S 144 volt battery. The operating voltage range is 162 volts down to 113 volts. If Peter looks at the volt meter on the controller and sees say 150 volts all is good right? Not necessarily because Peter could have 1, 2, 3 or even more cells setting at less than 2.5 volts and destroying them and never know it until it is too late.

                        But John uses a 4S 12 volt system with a operating range of 13.8 to 12 volts. If John has a week cell he knows immediately right?

                        See what I am driving at?

                        EV manufactures do something you cannot. They use matched cells, within 1% capacity tolerance. Rarely if ever do they Balance the cells. In fact none of them would ever allow you to fully charge the EV pack. If they did, they could not offer the long warranties. The lithium cells they use only have 500 cycle in them if fully charged up. EV limit the customer to 90/10 at most. Some even tighter limits. at 80/20.

                        OK you can mimic what commercial EV manufacturers do by Bottom Balance and run in the middle. The real dander of LFP is over discharge. When you Bottom Balance you eliminate over discharge and you do it passively requiring nothing more than setting your Inverter LVD to 12 volts if it allows it. If not most Inverters default at 10.5 volts which will also work. When you Bottom Balance all cells wil be 2.5 volts when discharged. That is 10 volts. Damage is at 2 volts per cell or 8 volts.

                        If you are going to use anything, all you need is cell voltages and guess what you can use? Either a Cell Pro 8 or better for you it smaller brother Cell Pro Multi4. Use the LVD to protect over discharge, limit charge voltage to 13.6 to 13.8, and so you can sleep at night a cell monitor to keep an eye on voltages.

                        One word of caution. If you bottom balance you must know about lithium batteries. So far you are doing your homework. If you really want a BMS look at an Orion Jr. It will work up to 16S and you do no thave to use the Balance Feature, Just use it to monitor cell voltage and temps. It can even interface to a LVD and HVC if you want. Just do your homework.
                        MSEE, PE

                        Comment


                        • #27
                          Originally posted by Sunking View Post
                          OK let's get one thing straight, I am NOT telling you cannot use a BMS. OK?
                          I thought you were leaning towards no-BMS, but thanks for clarifying. I am sure you and I both are aware of quite a few YouTubers that are anti-BMS. I just happen to not be one of them.


                          If you are going to use anything, all you need is cell voltages and guess what you can use? Either a Cell Pro 8 or better for you it smaller brother Cell Pro Multi4. Use the LVD to protect over discharge, limit charge voltage to 13.6 to 13.8, and so you can sleep at night a cell monitor to keep an eye on voltages.
                          Thank you for pointing out a less expensive option for bottom-balancing.


                          One word of caution. If you bottom balance you must know about lithium batteries. So far you are doing your homework. If you really want a BMS look at an Orion Jr. It will work up to 16S and you do no thave to use the Balance Feature, Just use it to monitor cell voltage and temps. It can even interface to a LVD and HVC if you want. Just do your homework.
                          I am not seeing the advantage of the Orion Jr over the Elite Power BMS. Both are capable of LVD and HVC, both passively cell-balance. The Elite system includes a shunt and provides cell-level voltages, temperature, pack SOC, charge rate/discharge rate, all on a nice 7" LCD monitor. This is similar to the functionality of the Victron BM702 that everyone loves, however the Elite system provides more information. The only differences I can tell between the Elite and Orion Jr systems is one has the vampire boards (500mA spec) on the battery terminals while the Orion Jr does it internal to the BMS unit and is rated at 200mA shunt rate. Beyond capabilities I do not require, is there something I am missing?

                          From the Orion literature: "The Orion BMS uses passive balancing to remove charge from the most charged cells in order to maintain the balance of the pack. The passive shunt resistors dissipate up to 200mA per cell. While that amount may seem small, that current is more than sufficient for maintaining balance in very large battery packs."

                          It seems to me that the method the BMS uses for cell-balancing is almost a moot issue if I am successful in setting my solar charge controller and my 120V shorepower charger to never let the batteries reach a SOC that would trigger cell-balancing. LVD and HVC are obviously very important.

                          I am sorry you are having to spoon-feed me. I am trying to read up on the technology BEFORE I buy the batteries, SCC, inverters, etc., but quite frankly this thread has helped me far more than anything I have read elsewhere, so thank you.

                          Comment


                          • #28
                            Originally posted by ASprinter View Post
                            I thought you were leaning towards no-BMS, but thanks for clarifying. I am sure you and I both are aware of quite a few YouTubers that are anti-BMS. I just happen to not be one of them.
                            No I am not anti-BMS as some may lead you to believe. They have their place on larger systems, and for people who do not care to learn anything about Lithium batteries. Great example if you have watched the news is a fire in an apartment complex killing a little girl. The BMS malfunctioned. Those Hoover Boards now have 120 fires to their credit and 1 death. Just a fact. Damn Chi-Coms cheap junk.

                            You have a 4S system, not 45S or 100S like an EV. You are using LFP which is fairly safe and moderately tolerant to over charge voltages up to 4.2 volts per cell before you run into the danger of THERMAL RUNAWAY like on the HOOVER BOARDS and EV's that do not use LFP. Couple that with the 2.0 volts minimum on a 4S system gives you a operational Window of safety of 8 to 16.8 volts. You will not even come close to those limits if your Inverter LVD is set for 12 volts and Charger set to 13.8 volts. It you see your battery voltage less than 12 volts, you know you got a problem and do not need a BMS to tell you that.

                            FWIW you cannot define a BMS, there is no Industry definition. A simple Volt meter qualifies. So does a Cell Level Voltage Monitor


                            Originally posted by ASprinter View Post
                            I am not seeing the advantage of the Orion Jr over the Elite Power BMS. Both are capable of LVD and HVC, both passively cell-balance. The Elite system includes a shunt and provides cell-level voltages, temperature, pack SOC, charge rate/discharge rate, all on a nice 7" LCD monitor. This is similar to the functionality of the Victron BM702 that everyone loves, however the Elite system provides more information. The only differences I can tell between the Elite and Orion Jr systems is one has the vampire boards (500mA spec) on the battery terminals while the Orion Jr does it internal to the BMS unit and is rated at 200mA shunt rate. Beyond capabilities I do not require, is there something I am missing?
                            The Orion can do everything the Elite can do and more. The Orion is Program Loop Controller you can fully customize. Lot's of EV guys use them with Bottom Balance to monitor everything you can with the Elite. An EV uses them also for a speedometer and Fuel Gauge as the Orion has a Coulomb Counter. A Coulomb Counter measures Amp Hour in and Amp Hours Out. It tells you pretty much exactly what the battery SOC is. The Orion also uses CAN BUS. It just does a lot more, fully programmable, data logging, trouble codes, and can communicate with other electronics via the Can Bus. It is tailored to EV's

                            Originally posted by ASprinter View Post
                            From the Orion literature: "The Orion BMS uses passive balancing to remove charge from the most charged cells in order to maintain the balance of the pack. The passive shunt resistors dissipate up to 200mA per cell. While that amount may seem small, that current is more than sufficient for maintaining balance in very large battery packs."

                            It seems to me that the method the BMS uses for cell-balancing is almost a moot issue if I am successful in setting my solar charge controller and my 120V shorepower charger to never let the batteries reach a SOC that would trigger cell-balancing. LVD and HVC are obviously very important.
                            OK both the Elite and Orion use the exact same methods to balance, they bleed the cells or Shunt. Only the shunt currents are different. The Orion is a Centralized Active BMS and fully programmable because they use a TI Chip Set. Your Elite, not certain, but I do not think you can program what voltage it triggers on, nor can you disable it. On the Orion you can program the Shunt Balance to any voltage you want, or disable it so it never turns on. I suspect the Elite you have no control over and is just a passive Bleeder Board. Those have a tendency to fail Shorted out Bleeding your cell to death. That is where the bad reputation comes from.

                            Originally posted by ASprinter View Post
                            I am sorry you are having to spoon-feed me. I am trying to read up on the technology BEFORE I buy the batteries, SCC, inverters, etc., but quite frankly this thread has helped me far more than anything I have read elsewhere, so thank you.
                            No Sir I am happy to do it.

                            You can use a BMS if you want an extra set of eyes. Just be aware of the danger using one with passive Bleeded Boards. They do not use chip sets that the industry uses. Most are Chi-Com like Hoover Boards. I am not saying DO NOT USE them. All I am saying is for a 4S battery they are not needed if you know what you are doing. The biggest flaw with a BMS is they use Top Balance topology, which requires you to fully charge the battery to 100% SOC. Charging any lithium battery to 100% SOC shortens battery cycle life and runs a much higher risk of thermal runaway. That is precisely why commercial EV manufacture do not allow you the customer to fully charge the EV battery. Like the Orion they use a TI Chip Set to control the SOC and not allow you to fully charge. It only monitors the cells and rarely ever does any balancing except when necessary and never 100%, some where in the MIDDLE. They can do that because they use matched cells.

                            If it were me in your shoes, I would use a cell level monitor, no Balancing. Use the right hardware and you can use it as a secondary fail safe in the event your Inverter LVD fails, or for whatever reason the Charger goes stupid and supplies more than 14 volts. Example if any cell drops below 2.6 volts for more than 15 seconds, disconnect the battery. If any cell goes above 3.6 volts disconnect the charger. I know both the Orion and Cell Pro can do that on their own. I do not know if the Elite can or cannot. Last time I looked at it a few years ago I was not impressed.

                            FWIW A few years ago being an engineer I was in the camp of: One Must Use BMS. Not today, I got educated from bad experiences living in that camp. Damn Bleeder Boards sent me packing..

                            EDIT NOTE:

                            If you have not bought your batteries as of yet I sugest you use CALB over GBS from Elite. CALB are less expensive, higher quality and last a lot longer. If something does go wrong you have a batter chance on warranty claim with CALB. EV guys like myself learned that lesson the hard way. My first LFP for my cart was GBS, I got rid of them after 6-months for CALB. But I do not have the CALBS anymore either. Sold them to a friend who still uses them in his cart. The GBs were sold to another person and they died in 6 months. Today I use Leaf Modules going on two years now.

                            Here is a GOLD MINE web site ran by a friend and fellow EV Designer. Every BMS and Lipo battery is there. David owns his own company and makes BMS systems out of Boulder CO. We don;t always agree, but I do not hold that against him as he smokles dope like cigarettes. That is why he live in Boulder. He offered me a job some years back when I wanted to retire for the 2nd time. His BMS uses a Custom IC he designed and manufactured by Atmel if I remember correctly.
                            Last edited by Sunking; 03-14-2017, 02:40 PM.
                            MSEE, PE

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                            • #29
                              And I was just feeling confident about my equipment purchase and you had to throw down a post like that. <--Note the smiley. As a summary, this is an electrical system being placed into service in a high roof Sprinter van. 200 aH of lithium batteries, single 305W LG solar panel(32.5 Vmpp, 9.26 lmpp), Victron 75/15 solar charge controller as primary source of charging, Magnum MMS1012 1000W pure sine inverter/charger/transfer switch (confirmed that this unit has fully customizable charge settings)--keep in mind this unit will charge the house batteries when plugged into 120V shorepower and I will also have the capability to use a second 600W pure sine inverter that will be used to feed alternator power to the Magnum inverter/charger to charge the batteries when driving. Even though there are two electrical losses in the inverters, the ability to run small gauge AC wires from the front of the van to the rear where the house batteries are located is a big plus. Also needed is a battery monitoring system to track useage.

                              I like the GBS/Elite system for several reasons. I like the packaging as it fits where I want it to go, I like that the cells are banded together, the 4-screw terminals and the caps that cover the I terminals. I like that many RVs and boats are using this system with good feedback and I have a personal friend using this system. Because it's a complete package, tech support is available if I run into install problems. I love the way the LCD displays battery SOC, charging/discharge rate, individual cell voltage and temperature. Basically, I didn't have anything to not like until you brought up the vampire board issue. It sounds to me like this is one of the bigger issues you have with the components I'm looking at, and I get the impression that use of the Orion Jr TI chipset resolves this issue. What it means to me is trying to figure out how to get all of the above working with the Orion Jr, as the Elite system comes with everything I need (including the LVD and HVC contactors) and installation is well-documented since it is designed for use in boats and RVs.

                              I searched around and found pretty extensive use of the Orion Jr in EVs, but not RVs. You have me interested, but perhaps you can tell me how achievable the Orion Jr method would be considering my needs.

                              As always, I'm enjoying the dialogue!

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                              • #30
                                Originally posted by ASprinter View Post
                                I like the GBS/Elite system for several reasons. I like the packaging as it fits where I want it to go, I like that the cells are banded together, the 4-screw terminals and the caps that cover the I terminals.
                                I did too and paid up for it just like you. What I did not realize at the time is the Internal Resistance of the cells. For an EV we need to be able to draw very high amounts of current in short bust of 10 to 15 seconds to accelerate. Example I was trying to pull 600 amps from 100 AH cells aka 6C. Well the cells can do that but due to high resistance the voltage collapses. OK do not panic because you will not ever make that demand because with a 1000 watt Inverter at 12 volts the most you can possible pull is 100 amps. On a 200 AH pack is only C/2 well within its capability. However I do not think they will last as long as CALB. Hard to say because I have never been able to test them under cream puff conditions of solar with low demand.

                                Tell me more about the Vampire Boards. What functions do they perform? Is it bleeding only? Or do they also measure the voltage and temp also? I suspect they do it all if I remember correctly. Been a while since I looked. Don't worry to much about them because essentially if your charger never goes above 13.8 volts, they should never trigger the bleeders. And if you ask me nicely I can tell you how to disable them. They have a power resistor to burn the power off when turned on. Cut one end of it and open it up. Think of it like a washed out bridge.

                                Don't worry about the Orion Jr. Go on with your plans.

                                Anyway to see where GBS batteries fall on the ole quality scale click this link. It is one of the pages I already gave you from David. It is called a Short Discharge Time. It is a theoretical time it would take to fully discharge any battery type or any capacity with a dead fault short. Not something you can really do but is based entirely on the Internal Resistance of the battery. Tells a designer the quality and if the battery is a good match for his application The shorter the time, the better the battery is. You can clearly see where all the Chi-Coms fall at the bottom of the list. Don't freak out because it is tailored to EV. Search around David site. Try using the BMS Selector tool. The Elite is in there and you can compare it to other options.

                                MSEE, PE

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