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  • Battery Charging Parameters

    I'm trying to set up my new charge controller and need some advice on charging parameters. I have a bank composed of 4 Vetus 12 volt sealed batteries on my boat. The batteries are about 5 years old. I don't have the instructions that came with the batteries and Vetus has been of no help. The stick on the batteries says:
    Boost voltage 14.5 - 14.9 volts
    Float Voltage 13.6 - 13.8 volts

    Is the Boost voltage the value I should set for absorption? or is this an equalization voltage? My bank is wired for 24 volts so I will be multiplying by 2

    Any advice appreciated

  • #2
    For comparison, here are the 12V battery voltages for the Morningstar TS-MPPT-150.

    IMG_1052.PNG

    This table has me a bit confused because I thought sealed batteries shouldn't get equalized.

    Comment


    • #3
      Some Mfg. recommend a "boost charge" for AGM batteries. It is an elevated voltage level but generally not enough to cause over gassing as you would see in flooded batteries. Sealed batteries, AKA VRLA(Valve Regulated Lead Acid) recombine the hydrogen gas back into the electrolyte but can only recombine so much before pressure causes the valve to open and vent. This venting causes loss of electrolyte which these batteries cant afford to lose. AGM batteries are roughly 98% saturated glass matt. loss of electrolyte is detrimental to them as it cannot be replaced.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

      Comment


      • #4
        Ho do you use your boat? Every other weekend would be the FLOAT settings. Daily usage I think would be for the Boost. Since they don't define the terms, I can't be sure.
        I'm thinking some batteries have different charge profiles for Daily Cyclic Use (Boost) or Standby Use (Float)
        AGM does not want much extra charge after the battery is filled.
        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


        • #5
          Vetus uses "boost" as equivalent to "absorb".

          https://www.vetus.com/electricity-on...-volt-5-a.html
          CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

          Comment


          • #6
            Originally posted by GreggN View Post
            I'm trying to set up my new charge controller and need some advice on charging parameters. I have a bank composed of 4 Vetus 12 volt sealed batteries on my boat. The batteries are about 5 years old. I don't have the instructions that came with the batteries and Vetus has been of no help. The stick on the batteries says:
            Boost voltage 14.5 - 14.9 volts
            Float Voltage 13.6 - 13.8 volts

            Is the Boost voltage the value I should set for absorption? or is this an equalization voltage? My bank is wired for 24 volts so I will be multiplying by 2
            Any advice appreciated
            What is the Make & Model of this new charge controller?
            Why did you change Charge Controllers?

            ALL manufacturers recommend a Boost / Bulk Charge Mode for their Deep Cycle AGM Batteries.
            YES => The Boost Voltage on the sticker is the Absorb Voltage in the Charge Controller, start at 29 Volts = 2 x 14.5 Volts.
            Your batteries are 5 years old, the Final Charge Voltage and Amps to get to 100% SOC will be different vs new batteries.
            How many more years do you think they have on this bank of batteries?

            Some AGM battery manufacturers recommend a Special AGM Equalization ( Recondition ) Charge mode, some do not.
            Vetus 24 Volt 40 Amp Charge Controler ...
            https://www.vetus.com/electricity-on...-24v-9952.html
            The above charge controller, simply does an 85 minute Bulk Charge every 12 days, which is NOT a true Equalization Mode charge.

            Exactly how does the "Equalization Mode" function on this new Charge Controller?
            I would not activate the Equalization mode on the new Charge Controller until I knew exactly what it was doing.
            Last edited by NEOH; 07-13-2017, 10:27 AM.

            Comment


            • #7
              Originally posted by GreggN View Post
              I'm trying to set up my new charge controller and need some advice on charging parameters. I have a bank composed of 4 Vetus 12 volt sealed batteries on my boat. The batteries are about 5 years old. I don't have the instructions that came with the batteries and Vetus has been of no help. The stick on the batteries says:
              Boost voltage 14.5 - 14.9 volts
              Float Voltage 13.6 - 13.8 volts

              Is the Boost voltage the value I should set for absorption? or is this an equalization voltage? My bank is wired for 24 volts so I will be multiplying by 2

              Any advice appreciated
              Do not get tripped up with catchy names like Boost, Equalize, Float or Bulk. For the most part it is garbage marketing of so called Smart Chargers. . They all mean the exact same thing and all are CC/CV. The names are just voltage set points. Nothing more, nothing less.

              The stickers give you the min/max values.

              Depending on your controller you want to set Bulk/Absorb from 29.0 to 29.8 volts, and Float to 27.2 to 27.6 volts. Being they are 5 year old AGM's are already due for replacement, and on solar go for the max voltages. 14.9 and 13.8 volts. There is no chance for thermal runaway on solar.
              Last edited by Sunking; 07-13-2017, 10:19 PM.
              MSEE, PE

              Comment


              • #8
                Hi all:
                My first post. Pleased to join the community.

                I taught basic Photovoltaic system design at a Tech. Voc Institution and I am an Engineer with MIT EE certification.
                Anyway, lead acid batteries are a particular expertise of mine.

                All lead acid batteries benefit from equalization or limited overcharging to eliminate electrolyte stratification and sulfation of the cells due to individual cell imbalance in the charge voltages in a long cell string.
                The caveat here is genuine GEL batteries cannot be equalized or they will form irremovable bubble voids in the gel and degrade battery performance. GEL batteries don't stratify the electrolyte at all.

                In the case of VRLA batteries such as AGM or even flooded cell recombinant batteries, equalization is beneficial, but overdoing it can compromise the electrolyte volume due to H2 and O2 losses. Increased electrolyte concentration will accelerate battery corrosion but provide higher cranking amps in the short term.

                The key to improving Lead acid battery longevity is to ensure their temperatures are cool (20C) .
                Last edited by AncelB; 07-13-2017, 10:14 PM.

                Comment


                • #9
                  Originally posted by AncelB View Post
                  Hi all:
                  My first post. Pleased to join the community.

                  I taught basic Photovoltaic system design at a Tech. Voc Institution and I am an Engineer with MIT EE certification.
                  Anyway, lead acid batteries are a particular expertise of mine.

                  All lead acid batteries benefit from equalization or limited overcharging to eliminate electrolyte stratification and sulfation of the cells due to individual cell imbalance in the charge voltages in a long cell string.
                  The caveat here is genuine GEL batteries cannot be equalized or they will form irremovable bubble voids in the gel and degrade battery performance. GEL batteries don't stratify the electrolyte at all.

                  In the case of VRLA batteries such as AGM or even flooded cell recombinant batteries, equalization is beneficial, but overdoing it can compromise the electrolyte volume due to H2 and O2 losses. Increased electrolyte concentration will accelerate battery corrosion but provide higher cranking amps in the short term.

                  The key to improving Lead acid battery longevity is to ensure their temperatures are cool (20C) . For every 8.3
                  You are preaching to the choir. The OP has Vetus AGM, not Gel. Voltage settings tell you it is not Gel as indicated by the voltage settings on the batteries. Welcome to the forum.

                  Gel batteries use lower voltage and slower charging algorithm to help prevent drying and cracking. They are not suitable for solar applications. Gels are pretty much limited to Float service in Emergency Egress Lightning and Fire Alarm Systems charged at a slow C/20. Solar needs much higher charge rates up to C/2 in some parts of the country.
                  Last edited by Sunking; 07-13-2017, 10:24 PM.
                  MSEE, PE

                  Comment


                  • #10

                    Pls have a look at this DIY effort of mine:
                    https://hackaday.io/project/25741-de...nge-mitigation
                    Last edited by AncelB; 07-13-2017, 10:31 PM.

                    Comment


                    • #11
                      Originally posted by AncelB View Post
                      Pls have a look at this DIY effort of mine:
                      https://hackaday.io/project/25741-de...nge-mitigation
                      I wonder if the overall idea works at all: many moons ago I tried to commercialize car batteries desulfation and the conclusion was this problem doesn't really exist if the batteries were maintained properly. In scope of that project we opened old batteries to analyze what leads to increased Ro and we found out the most common reason is breaking off battery 'subelement' electrodes from their element's 'output' bus. This caused switching out of entire subelement losing its useful area and hence increasing Ro. This effect seemed to be related to the current density and caused corrosion right at the spot where subelement was connected to the common 'bus' so one ends up with battery where elements look OK but they are not connected to anything.
                      One battery design surprised us a lot- they made element grid not out of perpendicular line conductors but rather from radially spreading conductors all originating from the output point of the subelement. These batteries were losing outer areas of subelements when aging but never broke off at the spots where subelements were connected to the element 'bus' as cross section of the lead was increasing towards that point. They had Ro in vicinity of 12-15 mOhm at 7 years of age. Their problem was electrical leaks developed by accumulating sediments at the bottom of the cells but they were quite capable of starting car if they were just charged.

                      Comment


                      • #12
                        The regeneration applies mainly to batteries which were not maintained properly and thus sulfated. Statistically this is between 20 and 33% of defunct batteries. At least from the few hundred I have done.

                        Comment


                        • #13
                          Originally posted by max2k View Post
                          I wonder if the overall idea works at all: many moons ago I tried to commercialize car batteries desulfation and the conclusion was this problem doesn't really exist if the batteries were maintained properly. In scope of that project we opened old batteries to analyze what leads to increased Ro and we found out the most common reason is breaking off battery 'subelement' electrodes from their element's 'output' bus. This caused switching out of entire subelement losing its useful area and hence increasing Ro. This effect seemed to be related to the current density and caused corrosion right at the spot where subelement was connected to the common 'bus' so one ends up with battery where elements look OK but they are not connected to anything.
                          One battery design surprised us a lot- they made element grid not out of perpendicular line conductors but rather from radially spreading conductors all originating from the output point of the subelement. These batteries were losing outer areas of subelements when aging but never broke off at the spots where subelements were connected to the element 'bus' as cross section of the lead was increasing towards that point. They had Ro in vicinity of 12-15 mOhm at 7 years of age. Their problem was electrical leaks developed by accumulating sediments at the bottom of the cells but they were quite capable of starting car if they were just charged.
                          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.
                          MSEE, PE

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                          • #14
                            Challenge therein is enough sunlight regularly to do the job, else sulphation will set in.

                            Comment


                            • #15
                              Originally posted by GreggN View Post
                              I'm trying to set up my new charge controller and need some advice on charging parameters. I have a bank composed of 4 Vetus 12 volt sealed batteries on my boat. The batteries are about 5 years old.....
                              At 5 years, they are likely at end of life, unless they are very unusual batteries. What does the warranty period say - 24 or 36 months ?

                              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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