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Don't think I'm getting enough current from my system...

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  • Don't think I'm getting enough current from my system...

    First of all, let me describe my system. 2 X 270 W panels.
    MPPT ML2430 solar controller 30amp
    Inverter tundra 2500w 24v
    4 crown CR430 6v bateries (14 months of use). (in a garage, in a 1 inch styrofoam box... for the cold!)
    Intelligent charger for my generator

    Here's what it's used for. 1 Cellular signal booster (110v)
    8 lights (110v...7 w leds...soon to be on 24v to skip the inverter)
    1 fridge 24 v around 1.6 amp
    I'm using the system on the weekends. Turn inverter of before leaving.

    Here's the problem:

    During the winter: (about 4 hours of daylight)
    In the middle of the day, solar controler always indicates 100% charge. At the end of the day, percentage gets rapidly lower (like 60%). If I turn lights on, or use few things on the 110v, or if the fridge starts, percentage drop drastically (sometimes under 30%). If I turn everything off, percentage goes back up (around 50%). I thought the battery wasn't fully charging but they get into float charging mode even sometimes in equalization mode. Voltage values seem to vary according to the percentage (not measured with a multimeter but on the solar controller window). Almost every weekend, I charge the battery with the intelligent charger for a few hours and it doesn't seem to be a lot better.

    During the summer:
    A bit better. But percentage vary drastically rapidly also.

    Any hints on what might be the problem?
    Bad battery?
    Wrong wiring?
    Normal situation and I should not do anything?

  • #2
    Your 2 panels with a good MPPT controller, will only harvest about 400W. At 25V, that's only 16A, so they are only good for charging up a 160ah battery. If your batteries are 430ah, you have chronically undercharged them.

    You murderer !
    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

    Comment


    • #3
      Does buying 4 smaller batteries, let's say around 160 ah, might cover the needs i described and solve my problems or do I absolutely have to buy 2 other panels (to get to over 1kw) and 4 new 430 ah batteries? I've already invested more than 5000$ in the project...

      Comment


      • #4
        After few minutes of thinking and calculating, I've realized 160 ah batteries wouldn't do the job as I'm needing at least 2kwh/day. But what bugs me is that I only use the system 2 days a week. Shouldn't the batteries recharge from Monday thru Friday (while I'm not there) even if the c/10 is not respected? And let's not forget I recharge with my generator during winter few hours a day when I'm there. Let's say I use 5kwh/week...Isn't my way of using the system able to do the job.

        Comment


        • #5
          Nope. As you found out, when you take several days to "recharge" that also gives the batteries several days to sulfate. Sulfation starts below 85% of full (some say 90%, some 80%) and the longer the battery sits below 85%, the harder the sulfation sets up. The reason 16A is too small, is it cannot provide enough energy to bubble agitate the cells, and the electrolyte starts to stratify, acid on the bottom, water on the top.

          Sulfation is the reason for a battery charging up quickly from a low state, and then draining down just as quickly. Stratification just helps it happen faster.
          https://batteryuniversity.com/learn/..._to_prevent_it

          AGM batteries solve the stratification problem, but even they will sulfate if not charged properly. LFP cells would work, but it's cheaper to learn care and feeding of batteries on cheap golf cart batteries. 2 parallel strings of 4 batteries (just $800 at costco) would give you 24v 400ah, but you really need more solar, or it's replacement time again.

          The fridge operation - once it's cold (which takes 24 hours) you might be better leaving it running between visits so you don't have a terrible start up drain every week when you turn it on. Have you measured what the fridge actually consumes ?

          Do you know what your inverter consumes when on but idle ? Is it a pure sine wave, or mod sine ? ( I see it's Mod-Sine, another bad news item, that will cause your fridge motor to eventually overheat and die, plus causing at least an extra 20% increase of power consumption, and no idle power spec given)
          Last edited by Mike90250; 01-13-2020, 11:29 PM.
          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

          Comment


          • #6
            The fridge is only turned down during the winter. It’s about -15C in the cabin, so it’s already cold when i start it... it is connected on the solar controler 24v load output. It uses 2.5 - 3.5 ah. Don’t know for the consumption of the inverter. It’s pure sine wave.

            Comment


            • #7
              So what would be the best solution for me? Getting 2 other 270w panels (I would be 1080w), change the controller for a 60 or 80 amp (in case I need more energy some day). Then I would be around 43 amp at 25v for my 4 430ah batteries. Do you think the batteries are definitively unusable or will they be usable for a while if they get a better charge? By the way, my batteries are in my garage in a styrofoam box. temperature goes really cold out here (sometimes under -30°C in January and February). Someone told me I should keep the batteries inside, because they can't charge a lot in the cold weather.

              image001.png


              I'm wandering about the risk of fire with the hydrogen. There is a good air circulation but I'm a bit nervous to get them inside. What do you think about that?
              Last edited by Jambonjoebob; 01-15-2020, 02:53 PM.

              Comment


              • #8
                Lithium batteries cannot be charged when cold (below freezing) Lead acid is fine, they even age slower when cold.
                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

                Comment


                • #9
                  What about the graphic above?

                  Comment


                  • #10
                    Originally posted by Jambonjoebob View Post
                    What about the graphic above?
                    Graphic is for cycle life and available power when cold. Calendar life time is increased by cold temps (slower chemical reaction acid eating away the plates) , in warm areas, the acid eats away the battery faster than normal.

                    Lead Acid looses capacity when cold, your 400ah battery can only give you 200ah when it's really frosty, But it does not harm the battery. Capacity will recover when it warms back up to a normal temperature, Lithium batteries are MUCH worse when they get cold, Below 5C they get sluggish, and below 0C, you cannot charge them.

                    Only when you let the battery sit partiality discharged, or bake it in the desert, do you harm lead acid.

                    Freeze point Pb battery.jpg
                    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

                    Comment


                    • #11
                      So!

                      What is my best option? Let’s say I add 2 panels and change my controller, will the batteries get more capacity during winter (-20 to -30 C in January and February and few hours of sunlight) or will they stay at the same capacity, being limited by the cold temperatures? They are in a isolated box in a garage. Yesterday morning, batteries temp was -17C (no ice) I unplugged the solar panel and the batteries were at 7.2 V each. I also checked fluid with an hydrometer and it seems like the batteries are good. But when I turn the lights on or use something electric, the % drops drastically on the solar controller. If I turn them off % goes up, but not as high. I will check next week directly on the batteries if voltage drops. Might there be a problem in the wiring? My inverter is supposed to be a good one. What represents the % on the solar charge controller? (voltage v, capacity ah ?). By the way, during the summer, % doesn’t drop that low.

                      Comment


                      • #12
                        Battery CAPACITY lowers in cold weather. It's a chemical reaction and cannot be changed till warmed up

                        More solar panels will increase the power for recharging, which is helpful in the shorter winter days

                        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

                        Comment


                        • #13
                          Here’s an update. I installed my batteries inside the cabin to get more capacity.I changed my battery cables. Installed all the lights and the fridge on 24 v. Only turn on the inverter if needed and only at sun peak time. (Charging iphones, ipads, etc). Cellular booster on 12v (bought an 12 v converter). Booster drains 0,7 amps (24/24) and total amps never exceeds 2,5 amps, even when everything is on. Worst case scenario, 2,5 amp x 24 = 60 amp hours/day, assuming fridge and lighting works 24h witch isn’t happening. My charge controller reads 25-30 amp hours average every day. My batteries get to float charging everyday at around 2pm but as soon as the sun comes down, they drop at 57-61%. Then when the fridge starts, they drop instantly at 28 or 30%. Fridge stops and they go back at around 57. At 9 pm they vary from 28 to 52% and almost every nights(2-3 am), they are at 66%. Yesterday, at 4pm they were at 33% and I started my generator with the 40 amps intelligent charger for around 4 hours and they did not go a lot higher. They were at 33 when I went to bed and 66 at 5am. They do not miss liquid and I did a hydrometer check and got good readings. Batteries are 16 months old but frozed once last year.
                          what is the sequence to solve my problem?

                          Voltage variation is normal so stop looking at the numbers and enjoy life?
                          Look for wiring problem?
                          Buy more panels and new batteries?
                          Try new batteries?
                          Try buying more panels and keep using the batteries until they are completely useless?
                          Last edited by Jambonjoebob; 03-01-2020, 10:01 AM.

                          Comment


                          • #14
                            If flooded lead acid batteries ever freeze, they are generally considered ruined.

                            When batteries are charging, their voltage is normally about 14V When charging stops, they drift down to 12.5V over the course of an hour, or less if there is much load on them. Many simple battery meters are confounded by this change and report 50% or some such nonsense. You need to read your battery voltage and learn to interpret it for your conditions.

                            Your panels need to be able to charge your batteries at least at 10% of the Ah rating. if your bank is rated at 270Ah, then you need to be able to deliver 27Ah of charge into them to keep them healthy. The gassing bubbles in the cells stir up the electrolyte and keep it evenly mixed. Without this mixing, the batteries stratify.
                            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

                            Comment

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