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24V, 300Ah Batteries, 300W Solar System for a Van

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  • 24V, 300Ah Batteries, 300W Solar System for a Van

    I've been designing this system, it's a bit different to most in a van. Any feedback would be welcome.

    Features:
    - 24V Victron EasySolar with 2400W Inverter (3000VA) and 70A MPPT charge controller
    - 7.5Kwh Lithium Ion batteries from http://www.boston-power.com
    - BMS from http://zeva.com.au
    - 3x 300W panels
    - 24-12V DC-DC converter for 12V items

    Overall view of the plan:
    https://www.dropbox.com/s/mh1nay7oan...%402x.png?dl=0

    I put up a slightly long (10min) video tour of the plan here:
    https://www.youtube.com/watch?v=DY3-6wZqA4o

  • #2
    Given your Loads...

    a) Refrigerator
    b) Microwave
    c) Induction Cook Top
    d) Pressure Cooker
    e) Dish Washer
    f) Electric Blanket
    g) Water Heater
    h) Water Pump
    i) Lighting
    j) Fans
    k) TV, Stereo, Play Station, etc

    Have you done your Daily Load calculation ?
    How many days will the Battery Bank last without any solar ?
    How many days will it take for PV to recharge the fully discharged battery bank, while also supporting the Daily Loads ?
    Last edited by NEOH; 08-09-2017, 10:18 AM.

    Comment


    • #3
      So it may look ridiculous, but most of that wouldn't be used unless energy is available. e.g. home entertainment would probably only be used when plugged into shore power. Induction cook top would only be used in summer when battery allows. I'll have gas cooking the rest of the time. The electric water heater will be relay controlled, so will only come on if batteries are full, and PV is still pulling in decent power. There will be a diesel water heater the rest of the time. But I still want it all on the plan. I may drop some of those things yet as well, e.g. dishwasher and playstation will be first to go as you can imagine. Weight is my biggest issue.

      The actual daily usage of essentials e.g. fridge, laptop, iphone charger, lighting, water pump, heater (diesel pump only) comes to 1920Wh, and assuming 300Ah @ 24V @ 80%DOC = 6336Wh. So about 3.3 days of usage from the batteries assuming no input at all. More if laptop doesn't operate at full power (which it doesn't) and I'm more frugal.

      In peak summer, the PV should pull in 4466Wh/day, and worst in winter around 1200Wh/day. So I'm expecting ~3 months of the year where I'll need to plugged in often. Or be away house sitting. The rest of the year, especially over summer, I want to be off grid as much as possible.

      Because I'm going to be living in the van, I'm happy to be plugged in wherever needed. We have a network of campgrounds in NZ that are quite cheap. So if it's raining for a week for example (which is quite common in NZ), I'll probably go plug in somewhere.

      Excellent questions, and it's important others new to solar don't get the wrong idea from my system. It's not possible to run a normal house from 3PV panels!

      Comment


      • #4
        Oh forgot to say, I have a plan for getting power from the alternator when driving too. A bit tricky with 12-24V, but the easiest solution (but not very efficient) is to run a 12-230V inverter off the van (that's only active when car is on), and feed it into the shore power of the Victron box. Roughly 90% efficient for a 800W inverter. Plus it then needs to be converted again to charge the batteries. (93% efficient). Alternatively I'll need to find a DC-DC 12-24V converter that can handle 30Amps+

        Comment


        • #5
          Hi everyone,
          I am new to this forum, live on a sailboat, and have a set of questions.
          I have just ordered 4x200Ah Victron LiFe batteries.
          My charging system includes
          - Solar panels (3x165W) with a Morningstar PS15 controller
          - WindX wind generator with internal regulator
          - 6kVA diesel DC generator with external voltage control
          - 75A Alternator (Balmar) with external regulator
          - Victron shorepower charger
          I have 2 problems:
          1. The batteries BMS will cut off power supply if any cell or the whole pack goes beyond a certain voltage. This, for the wind generator, diesel generator and shorepower is not a problem. However for the alternator and the solar panels it is a problem. For the alternator, I am installing a split diode system, so that even if the BMS shuts off the supply to the batteries, the alternator will still read some voltage from the second - non lithium- battery, and will not start going crazy.
          The issue is with the solar panels. If the BMS cuts off the supply to the batteries, the Morningstar controller will itself have no power, and will not function once the BMS reinstates the link to the batteries.
          Anyone has any experience with this, and what would be the solution?
          2. Lithium batteries, I understand do not want any trickle power once full. All of the existing charge elements (solar, diesel generator, alternator, shorepower) have a charging process that switches to float (i.e trickle) once a certain voltage and amp. is reached. I read that if the float voltage is set to 13.6V, there will be no problem for the lithium batteries. Is this correct, or is there another way to avoid over-charging or to avoid the batteries to be at or very near 100% all the time (short of turning all charging elements off manually, which is absolutely not practical on a boat).

          Thanks for any valuable input
          Sailmaryann

          Comment


          • #6
            Originally posted by sailmaryann View Post
            1. The batteries BMS will cut off power supply if any cell or the whole pack goes beyond a certain voltage. This, for the wind generator, diesel generator and shorepower is not a problem. However for the alternator and the solar panels it is a problem. For the alternator, I am installing a split diode system, so that even if the BMS shuts off the supply to the batteries, the alternator will still read some voltage from the second - non lithium- battery, and will not start going crazy.
            The issue is with the solar panels. If the BMS cuts off the supply to the batteries, the Morningstar controller will itself have no power, and will not function once the BMS reinstates the link to the batteries.
            The BMS should only disconnect the battery if there is a fault or if the external voltage being applied to the battery is too high or if the battery is discharged too far. It should not be disconnecting the battery during normal operation.

            What battery type have you got the Morningstar PS15 set up for, Gel, Sealed or Flooded?

            What is the maximum voltage that your alternator is putting out?

            2. Lithium batteries, I understand do not want any trickle power once full. All of the existing charge elements (solar, diesel generator, alternator, shorepower) have a charging process that switches to float (i.e trickle) once a certain voltage and amp. is reached. I read that if the float voltage is set to 13.6V, there will be no problem for the lithium batteries. Is this correct, or is there another way to avoid over-charging or to avoid the batteries to be at or very near 100% all the time (short of turning all charging elements off manually, which is absolutely not practical on a boat).
            I don't think you should float a LFP (LiFe) for long periods of time. If you are running them off solar or wind and using the batteries all the time then floating at 13.4V is OK. If you are using shore power or your generator I think you should terminate the charge with an SOC below 70% and then recharge when the SOC gets to around 20%-30% SOC.

            Can you give us some details on what model battery and BMS you have purchased

            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; 08-11-2017, 10:24 PM. Reason: Added question on batteries
            Off-Grid LFP(LiFePO4) system since April 2013

            Comment


            • #7
              Hi Simon,
              I don't have the Li batteries yet, but am planning to either buy a programmable solar controller (which one?), or set up my existing one to gel.
              My alternator is a 75A Balmar, and it can do equalize at 15V. It is currently set to boost at 14.4V, but I plan to set it to 14V boost, 13.6 float with the new batteries. I will keep my battery isolator to avoid a problem in case of Cyrix or BMS shut off.
              As I mentioned in my post, the batteries are Victron's 200Ah Li Fe PO4 batteries with built in BMS. I also bought the Cyrix Load and Cyrix Charge elements as a second line security.

              My concern is that on a sailing boat,underway, during the day the solar panels and wind generator are pumping in amps all the time, but mostly keep up with consumption with a bit left over for storage. When at anchor, the input remains, but the demand is less of course. I don't want to have to run around switching things on and off to keep the batteries in the right range of charge. Right now, with my flooded Pb batteries, I just keep charging, the systems take care of reducing the charge when appropriate and I don't risk damaging the batteries.

              Regarding your advice to charge to 70% when running the generator or shore charger, that sounds great, but how do I know I am at 70% or 20%? With the traditional batteries, just reading the voltage tells me that, but with LI batteries and their stable voltage throughout their capacity range, I wonder.

              Comment


              • #8
                Is it the Victron LFP-BMS 12,8/200 batteries that you have ordered?

                14V boost and 13.6V float are OK, I would be slightly more conservative and charge at 13.8V and float at 13.4V. If you are not monitoring the individual cell voltages, to balance the battery I would do an "equalise" charge to 14.2V for about an hour once a month. If you are monitoring the individual voltages you could do an "equalise" when they became unbalanced.

                When your boat is at anchor you could set the solar and wind boost and float voltage to ~13.0V which will keep your battery with an SOC around 30%.

                You could use a Vicron BMV-700 or something like it to monitor the SOC of the battery. It has a relay output that you could set to turn on shore power charger or your generator at say 20%SOC and turn off at say 50%SOC to let the sun and wind do as much charging as possible. The BMS-700 counts the amount of current going into and out of the battery to work out the SOC. This is very accurate because the coulomb/current efficiency of LFP batteries is greater than 99%.

                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

                Comment


                • #9
                  Originally posted by sailmaryann View Post
                  Hi everyone,
                  I am new to this forum, live on a sailboat, and have a set of questions.
                  I have just ordered 4x200Ah Victron LiFe batteries.
                  My charging system includes
                  - Solar panels (3x165W) with a Morningstar PS15 controller
                  - WindX wind generator with internal regulator
                  - 6kVA diesel DC generator with external voltage control
                  - 75A Alternator (Balmar) with external regulator
                  - Victron shorepower charger
                  I have 2 problems:
                  1. The batteries BMS will cut off power supply if any cell or the whole pack goes beyond a certain voltage. This, for the wind generator, diesel generator and shorepower is not a problem. However for the alternator and the solar panels it is a problem. For the alternator, I am installing a split diode system, so that even if the BMS shuts off the supply to the batteries, the alternator will still read some voltage from the second - non lithium- battery, and will not start going crazy.
                  The issue is with the solar panels. If the BMS cuts off the supply to the batteries, the Morningstar controller will itself have no power, and will not function once the BMS reinstates the link to the batteries.
                  Anyone has any experience with this, and what would be the solution?
                  2. Lithium batteries, I understand do not want any trickle power once full. All of the existing charge elements (solar, diesel generator, alternator, shorepower) have a charging process that switches to float (i.e trickle) once a certain voltage and amp. is reached. I read that if the float voltage is set to 13.6V, there will be no problem for the lithium batteries. Is this correct, or is there another way to avoid over-charging or to avoid the batteries to be at or very near 100% all the time (short of turning all charging elements off manually, which is absolutely not practical on a boat).

                  Thanks for any valuable input
                  Sailmaryann
                  Sailmaryann, Welcome to the forum. You will get a better response if you start your own thread instead of jumping into another's actively running thread.
                  2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                  Comment


                  • #10
                    Simon, yes it is the Victron LFP-BMS 12.8- 200. I understand this does the cell balancing automatically, of course I will have to give it a somewhat higher voltage than 14V once in a while.
                    On the BMS side, I now have a Victron BMV 501, a somewhat older model, but should be accurate enough if I set the Peukaert number right. So, if I get you right, the way to proceed, is to charge the new batteries full when I first install them - to the point where the Cyrix charge stops the charging, then set my BMV to zero (100% SOC), and then monitor how many Amps are going out to determine the SOC of the batteries. With 800 Ah, this means I use about 560A (to reach 30% SOG), then charge, say 200Amps to 400Ah for 50% SOG. This way I stay within the 30-50% SOC range. Makes sense. I still have to find a solution for the solar controller to avoid an unplanned cut off which would disable the solar controller.

                    Comment


                    • #11
                      Little Harbour, point taken. I didn't know how to start a new thread...(still don't, but I'll figure it out.).

                      Comment


                      • #12
                        I am in a bit of a hurry so will keep this brief.

                        The BMV 501 has pretty much the same functionality of the 701. Set the Peukaert factor to 1.00. You will have to set the point to reset the SOC meter when the battery is full depending on your charge voltage and end charge current.

                        I would have a look at the Epever MPPT controllers which are made by EPSolar. I have had no problems with a EPSolar controller that has been installed for over 4 years.

                        To start a new thread you have to use the "Solar Panel Forums" tab, click on the forum you want to start the new thread and yo will see a button + NEW TOPIC.

                        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

                        Comment


                        • #13
                          In the top left corner of any page click on the Solar Panels Forums tab. Scroll down to the category you want to post in. such as Batteries / energy storage,Once on that category scroll down to the list of threads, you will see in the top left corner a blue box that says + New Post, click on it, give it a title and you're set.
                          Last edited by littleharbor; 08-13-2017, 07:44 AM.
                          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                          Comment


                          • #14
                            Originally posted by sailmaryann View Post
                            Simon, yes it is the Victron LFP-BMS 12.8- 200. I understand this does the cell balancing automatically, of course I will have to give it a somewhat higher voltage than 14V once in a while.
                            I had a look at the manual for the Victron 12.8-200 and they suggest a commissioning charge of 14.2V (3.55V/cell) for several hours to balance the battery. I would think that this means that you wouldn't have to go any higher than 14.2V for the automatic balancers to work.
                            On the BMS side, I now have a Victron BMV 501, a somewhat older model, but should be accurate enough if I set the Peukaert number right. So, if I get you right, the way to proceed, is to charge the new batteries full when I first install them - to the point where the Cyrix charge stops the charging, then set my BMV to zero (100% SOC), and then monitor how many Amps are going out to determine the SOC of the batteries.
                            Maybe I am missing something but from the Vicron documentation it looks like the Cyrix charge and Cyrix load modules are just relays or solid state switches and need to be connected to the VE.Bus BMS unit which is connected to the batteries. Are you getting the VE.Bus BMS?

                            If the batteries were 100% efficient and there were no errors in measuring the battery current you could set the BMV just once and it would always be accurate. Because the batteries are not 100% efficient and there are errors in reading the current it has to be reset on a regular basis.

                            The difference in SOC between charging to 13.8V (3.45V/cell) at an end charge current of C/20 and the voltage the VE.bus BMS signals the Vyrix charge module to stops charging (4.0V/cell) is only a couple of % so it makes sense to call 13.8V at an end charge current of C/20 full and use this to reset the BMV.

                            With 800 Ah, this means I use about 560A (to reach 30% SOG), then charge, say 200Amps to 400Ah for 50% SOG. This way I stay within the 30-50% SOC range. Makes sense.
                            I would only do this is you are charging from the generator or shore power. I would charge to ~100% if using solar and wind when at sea or if living on the boat and float charge at ~50% SOC using the solar and wind if the boat is not being used.
                            I still have to find a solution for the solar controller to avoid an unplanned cut off which would disable the solar controller.
                            I don't think this will be a problem for two reasons
                            1. Unless there is a fault the BMS should never disconnect the battery from the charge controller.
                            2. If the BMS did disconnect the battery from the charge controller it would be while there was was power coming from the solar panels so the solar controller would remain powered up. The battery would be reconnected to the solar controller when all the cell voltages dropped below 4.0V


                            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

                            Comment


                            • #15
                              Simon, I am indeed getting the VE bus BMS. Thank you very much. I think I am clear now about how to set this up and run it.
                              Appreciate your help.

                              Comment

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