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Battery Charging Parameters

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  • #16
    Originally posted by Sunking View Post

    For the most part battery desulphators are more voodoo, than science. 95% of all battery failures are sulphation. The two root causes are the natural aging of batteries, and/or chronic undercharging. Even well maintained batteries will die from sulphation. You cannot stop it, only minimize it.

    The other 5% is what you mostly see in auto SLI batteries, corrosion just as you describe. A SLI battery is not a deep cycle battery. As you noted a SLI battery plates fill the jar to the bottom. Where as a True Deep Cycle battery doe snot completely fill the jar. They leave room in the bottom of the jar for sediment, flaking, and scaling. Helps prevent the plates from shorting out.

    Although this discussion has anything to do with the OP because he is using FLA batteries. Solar has revised battery manufacturers charging guidelines. Before Off-Grid became popular the users of Deep Cycle Batteries were Golf Carts, Fork Lift, Floor machines, and some Marine and RV users. All those users just became accustomed to replacing the batteries every 2 or 3 years. Charging guideline were written for Ac chargers that do not have power or time limits.

    A great example today is Trojan. Before Solar Bulk/Absorp was 2.35 to 2.4 vpc (14.1 to 14.4 volts). Not today. When solar users used those voltage guidelines, battery manufactures got slammed with warranty claims. Solar charging just falls short as there are not enough hours to apply a proper Saturation, aka Absorb. Secondly most solar users panel wattages are grossly undersized. compounding the problem. As a result, battery manufactures discovered the failures were chronic undercharging, or sulphated batteries.

    So they change charging guidelines and raise charge voltages. Case in point Trojan upped it to 2.45 to 2.5 vpc or 14.83 volts on a 12 volt battery. In a solar system you want to error on the Corrosion side of the knife. Over charged batteries last longer than undercharged batteries.
    very interesting, thanks for the info. I was mostly referring to the link AncelB posted as he mentions car batteries on that page. For the reference car batteries I had open also had some room at the bottom for sediment, etc but at 7 yo age all that was used up creating leaks. It sounds like we should not ever bother with SLI batteries for the solar or off the grid purposes in general as they would really need to get significant percentage of the charge back for the system to make economical sense so SLIs with their starting abilities at the expense of deep cycle look pretty useless for these purposes. I wish LiPo batteries were cheaper as I recall from my short experience with them they provide quite fast charge/discharge rates, deep cycle, good capacity. Modern electronics readily takes care of their more complicated charging/discharging voltage monitoring.


    • #17
      Originally posted by AncelB View Post
      Challenge therein is enough sunlight regularly to do the job, else sulphation will set in.
      Not necessarily just sunlight but there needs to be enough charging amps (produced from panel wattage) to properly charge and eliminate the plate sulphation. The sunlight is just to unpredictable to rely on keeping the batteries happy and clean. People need to also use another energy source to "kick" the batteries and reduce the sulfur that collects on the plates.


      • #18
        Originally posted by max2k View Post
        It sounds like we should not ever bother with SLI batteries for the solar or off the grid purposes in general as they would really need to get significant percentage of the charge back for the system to make economical sense so SLIs with their starting abilities at the expense of deep cycle look pretty useless for these purposes.
        Sli batteries are not suitable for any cycled application, they are not designed to do that. Pb batteries fall into 3 basic categories:

        1. SLI aka Cranking or Engine starting battery are designed to deliver very high quick burst of current, then be recharged very quickly. SLI batteries in the USA use lead-calcium alloy with many thin plates to increase surface area, thus lowering internal resistance so they can deliver those very high currents required. However lead-calcium and thin plates do not lend them selves for cycling and if pressed into cycle service will only provide as few as 50 up to 300 cycles. One note here another battery that uses Lead Calcium alloy is Stationary batteries used in telecom. Again very high currents, but not many cycles.

        2. Deep Cycle batteries can be either Lead-Antimony, Pure Lead Round Cells, Lead-Tin. US market is dominated by Lead Antimony. Deep Cycle batteries have much thicker and heavier plates, thus can supply up to a 1000 cycles. Some claim more. The one disadvantage of a true deep cycle is the internal resistance is higher than a design with more and thinner plates so they are limited in how much current they can deliver without excessive voltage sag. Typical limit is roughly C/8 to C/6 with some as high as C/4.

        3. Hybrid which come with many marketing names like Golf Cart, Fork Lift, RV, Marine Deep Cycle, Trolling, Wheel Chair, and the list goes on. These batteries use the same alloys as Deep Cycle but the plates are thinner and more of them again to increase surface area this lowing internal resistance. They try to be both SLI and Deep Cycle. The trade-off is cycle life. More cycles than SLI, but less than Deep Cycle.

        So SLI batteries really have no place in cycle applications, while Deep Cycle and Hybrid do have a place.
        MSEE, PE


        • #19
          Originally posted by AncelB
          I imagine that most folks on the forum do a good job of maintaining thier storage assets as they understand the technology.
          That is funny. Most that come here are clueless. Otherwise they would not come here asking why their batteries failed if they knew what they were doing.

          MSEE, PE


          • #20
            Originally posted by Sunking View Post

            That is funny. Most that come here are clueless.
            And some of those folks leave the same way, only more frustrated when they find out still others don't always share their alternate views of reality.


            • #21
              Originally posted by AncelB
              Maybe, but the project is not really experimental. I have the proof of concept data and the statistics in actual service, even thermal profiles. The commercial grade units tracks every battery and reports on success rates via IoT. This project provides the key basis for accomplishing regeneration of ill treated batteries. The automation is up to the builder based on their needs or interests.
              You should start your own thread, for your DIY project, instead of hijacking this thread....


              • #22
                Originally posted by AncelB
                guys...i am not adevertising or selling anything. It is an open source project...please read b4 accusing.
                I've actually had a tab open to it for a couple days now, and it's pretty interesting. However (and you state up front, vehicle use, and sized to fit the vehicle) it's not really useable for RE systems. So, further discussion should be on a new thread. Fine if you want to start one, but we mere mods can't split a thread. Just able to delete. I'll purge the noise now.
                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



                • #23
                  While I did design primarily for vehicles, the design is good to 250 Ah (6/12V)batteries including deepcycle like Trojan T105s. Which is why I mentioned it.
                  I'll start a separate thread if there's any more interest.
                  Last edited by AncelB; 07-23-2017, 02:13 AM.