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Proper charge controll settings for 12V AGM

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  • Proper charge controll settings for 12V AGM

    Hey All,
    I've got a MT50 controller hooked up to a Solar Epic Tracer 4215BN charge controller that is putting power into a 12V AGM.

    I'm currently using the suggested settings for a Gel battery and making the assumption that these settings will work for my AGM. Below is a chart that I retyped from the users manual, please forgive any typos. I can't say I fully understand which each of these rows means and the manual doesn't define them well. If someone out there has a resource on this please pass it along.

    One thing that gives me pause is the Low Voltage Disconnect Voltage line which is set to 11.1V. Based on my study of batteries so far if a 12V battery falls below 11.8V or so it dramatically reduces the life of the battery. Is this correct? If so should I change this to something higher than 11.1V?

    Any other considerations when configuring this charge controller and battery?

    Thanks
    Rich
    Battery charging setting Sealed Gel Flooded User
    Over voltage disconnect voltage 16.0V 16.0V 16.0V 9-17V
    charging limit voltage 15.0V 15.0V 15.0V 9-17V
    over voltage reconnect voltage 15.0V 15.0V 15.0V 9-17V
    Equalize charging Voltage 14.6V --- 14.8V 9-17V
    Boost charging voltage 14.4V 14.2V 14.6V 9-17V
    Float charging voltage 13.8V 13.8V 13.8V 9-17V
    Boost reconnect charging voltage 13.2V 13.2V 13.2V 9-17V
    Low voltage reconnect voltage 12.6V 12.6V 12.6V 9-17V
    Under voltage warning reconnect voltage 12.2V 12.2V 12.2V 9-17V
    Under voltage warning voltage 12.0V 12.0V 12.0V 9-17V
    Low voltage disconnect voltage 11.1V 11.1V 11.1V 9-17V
    Discharging limit voltage 10.6V 10.6V 10.6V 9-17V
    Equalization duration 180 min ---- 180 min 0-180min
    Boost duration 180 min 180 min 180 min 10-180min
    12V 12W panel, SolarEpic Tracer4215BN, 12V 18Ah

  • #2
    I think you should change your battery type from Gel to Sealed, although you are not hurting anything by using that setting. Note that those two are almost identical with the most notable difference being 0.2 V 'Boost' (Absorb) value and the enabling of Equalization. In the case of Sealed batteries (AGM) you shouldn't think of Equalization the same way as you do for Flooded, as the voltage isn't high enough to promote vigorous gassing, it is just using the Equalization 'label' to reuse the concept of a occasional 'freshening' of the battery.

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    • #3
      Richiep ,
      Why are you using GEL settings, when you have a Sealed AGM Battery?
      The battery voltage under-load varies tremendously and is not the same the a RESTING VOLTAGE.
      https://www.solarpaneltalk.com/forum...ischarging-agm
      Last edited by NEOH; 10-25-2017, 03:18 PM.

      Comment


      • #4
        FLA Battery Charge Voltage = 14.1 to 14.7 volts, Float = 13.5 to 13.6 volts
        AGM Battery Charge Voltage = 14.1 to 14.7 volts. Float = 13.5 to 13.6 volts
        Gel Battery Charge Voltage = 14.4 volts. Float = 13.4 volts to 13.6 volts

        Any questions?
        Last edited by Sunking; 10-25-2017, 04:18 PM.
        MSEE, PE

        Comment


        • #5
          Originally posted by Sunking View Post
          FLA Battery Charge Voltage = 14.1 to 14.7 volts, Float = 13.5 to 13.6 volts
          AGM Battery Charge Voltage = 14.1 to 14.7 volts. Float = 13.5 to 13.6 volts
          Gel Battery Charge Voltage = 14.4 volts. Float = 13.4 volts to 13.6 volts

          Any questions?
          For 36V battery bank I would assume X3 those numbers?

          Comment


          • #6
            Originally posted by SIGP2101 View Post
            For 36V battery bank I would assume X3 those numbers?
            Yes Sir your assumption is correct.

            MSEE, PE

            Comment


            • #7
              Originally posted by Sunking View Post
              FLA Battery Charge Voltage = 14.1 to 14.7 volts, Float = 13.5 to 13.6 volts
              AGM Battery Charge Voltage = 14.1 to 14.7 volts. Float = 13.5 to 13.6 volts
              Gel Battery Charge Voltage = 14.4 volts. Float = 13.4 volts to 13.6 volts

              Any questions?
              YIKES! Perhaps a typo there mixing gel and agm backwards. Easy to do.

              GEL is *much* more sensitive to overcharge than AGM. Thus, the highest CV voltage for GEL is 14.1v, but see the note below for the conspiracy about this.

              AGM is the one that takes 14.4 to 14.7v CV. Usually 14.7v is reserved for higher-performance types like pure-leads like Optima or Odyssey, whereas 14.4v is usually the limit for "conventional" (non pure-lead) agm's.

              Note for lurkers: Because consumers want convenience and not make many choices, charger manufacturers and even battery makes themselves *claim* that GEL can be charged just like AGM and that both can be charged to 14.4v. Not true - oh yes, a GEL charged at 14.4 will charge, but will overcharge to the point that even if you don't see it bulging or gassing, cycle life is severely reduced. Which leads to a trip back to the store for another gel replacement!

              And of course with gel's 0.1c max charge rating makes it twice as slow as the faster agm at 0.2 to 0.3c max for conventional agms. Sensitivity to overcharge, low current recharge, despite the touting of being truly deep cycle, makes gel a poor choice for solar.
              Last edited by PNjunction; 11-15-2017, 04:14 AM.

              Comment


              • #8
                Originally posted by PNjunction View Post
                YIKES! Perhaps a typo there mixing gel and agm backwards. Easy to do.

                GEL is *much* more sensitive to overcharge than AGM. Thus, the highest CV voltage for GEL is 14.1v, but see the note below for the conspiracy about this..
                OK you win. Please write Trojan and Rolls Battery. TELL them they do not know what they are talking about. Let me know how that works out for you.

                Right from Trojan User Manual:

                Wet aka FLA

                Bulk = 14.82
                Absorb = 14.1 to 14.7
                Finnish = 16.2
                Equalize = 16.2
                Float = 13.5
                C-Rate = 10 to 15% of C

                AGM

                Bulk = 14.4
                Absorb = 14.1 to 14.7
                Finish = 14.7
                Eq = NA
                Float = 13.5
                C-Rate = 20% of C

                GEL

                Bulk = 14.4
                Absorb = NA
                Finish = NA
                Equalize = NA
                Float = 13.5
                C-Rate = 10 to 13% of C

                Right from Rolls User Manual

                FLA

                Bulk = Absorb = 15.0 @ 25c
                Float = 13.5
                EQ = 15.6 to 15.9
                Rate = 10 to 20%

                AGM

                Bulk = Absorrb = 14.7 @ 25c
                Float = 13.8 @ 25c
                C-Rate = 10 to 30% of C


                GEL

                Bulk = Absorrb = 14.28 @ 25c
                Float = 13.68 @ 25c
                C-Rate = 10 to 30% of C

                So PN there is only one right answer, not Optima's manual. Read the manufactures manuals for a change. Any questions?





                Last edited by Sunking; 11-17-2017, 05:52 PM.
                MSEE, PE

                Comment


                • #9
                  If If Gel can be charged at C/10, how come it's not recommended for solar? Is it less tolerant of over-charging, or cycling?

                  Comment


                  • #10
                    Originally posted by sdold View Post
                    If If Gel can be charged at C/10, how come it's not recommended for solar? Is it less tolerant of over-charging, or cycling?
                    Gel batteries cannot tolerate any over charging. Gel application is really for Emergency Egress Lighting, and Fire/Alarm panels. In other words Emergency Standby Float Service.

                    So here is the problem with Gel batteries in solar applications. You would never ever be able to get them fully charged. To get a Pb battery fully charged with solar requires over voltage to force the controller to stay in Constant Power Mode aka Bulk. Otherwise you stand no chance of fully charging a Pb battery. FLA batteries are brutes and can tolerate moderate over charging and gassing. AGM's not so much, and Gel will not tolerate any over charging. What happens is you would dry the Gel out. As the gel dries out from over charging, it leave voids and cracks in the electrolyte which is capacity loss and irreversible damage so the damage accumulates and permanent. Stick a bowl of Jello in the fridge for a couple of weeks. Get the picture?

                    With FLA just add more water good to go. AGM's puff up and vent. Gel turns into your 100 year old ugly ars grandmother inside a coffin.



                    MSEE, PE

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