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  • Battery Over Charge voltages and Controller

    A few years ago I installed 2 140W Kyrocera Solar panel (in parallel) and a Morningstar Duo 25A 12VDC charge controller. My house bank is made up of 3 x 105A/H @ 20A AGMs, probably 3.5 Y/O by now. What I've been observing is during peak sun are over voltages going up to 16VDC.

    Besides the Morningstar Remote Monitor I also have a Victron BVM 602s and both are showing high voltages. My 750W inverter is also kicking off on high-voltage shutdown.

    Checking Solar input to the Duo shows about 20VDC (with + & - lead connected to the Duo) at the time I'm seeing the high voltages on the batteries.

    I've only recently observed the Duo LED status go from Green to Red on high voltage disconnect. This is a new Duo replacement as I had them send me another as the original Duo was suspect as I was incurring high voltages with it thinking its the controller.

    So basically I am at a loss on this issue and MorningStar says for me to check the batteries.

    As far as I can tell the batteries are doing OK, holding good charge, have minimal loading off hours (DC Refridgeration, LED Lighting, Boat Fan) and go back to 100% SOC shortly after sunrise and and SOC of 85% before sunrise. I suppose I could start disconnecting each battery at a time to see if I can find some issue but not sure what to look for...

    I'm in the Caribbean with high ambient temps too....so are the batteries creating an excess voltages or is the controller the issue?

    Any advice or opinion on why I'm getting high voltages would be greatly appreciated....

  • #2
    With a 140watt panel I presume it can generate about 7 to 8 amps. With 2 in parallel that gets you at least 15amps. Your battery system is 12v at 315Ah so that 15 amps is pretty slim to keep them happy. You really need about 30 amps for that system.

    You also mentioned you see a reading of 100% SOC shortly after sunrise yet you have an SOC of 85% before. I would think that it is almost impossible to charge that battery bank up 15% with so little amount of amps in such a short time.

    My guess is that the batteries are no longer rated 105Ah each and have been weakened to the point that they quickly charge and go over voltage so quickly.

    I think you need to check each battery to see if it really can be charged back to 100% and test to see how quickly they discharge.

    Comment


    • #3
      Originally posted by Bluwavguy View Post
      . My house bank is made up of 3 x 105A/H @ 20A AGMs, probably 3.5 Y/O by now. What I've been observing is during peak sun are over voltages going up to 16VDC.

      As far as I can tell the batteries are doing OK, holding good charge, have minimal loading off hours (DC Refridgeration, LED Lighting, Boat Fan) and go back to 100% SOC shortly after sunrise .
      Easy to trouble shoot. Your batteries are toast and need replaced. The only way you can get the batteries to go to 16 volts is if they are bad. You have described the classic sulfated battery.

      When you replace them do not buy 3 x 12 volt 105 AH batteries. That is part of your problem. You never ever want to parallel your batteries. When you replace them buy yourself 2 x 6-Volt 300 AH batteries.

      MSEE, PE

      Comment


      • #4
        SunEagle and SunKing, thank you both.

        I'll do some reseach on the sulfate battery issue...as the rise in voltage occurs momentarily...they will be sitting happy at 13.5...assume while the controllers (recently installed a 400w wind generator with it's own controller) are in float state...and then I'll notice (if I have my inverter running as the fan will increase it's rpm) the increase to 16 or just above and this lasts only a few seconds...then batt voltage will drop down to the mid 13's....

        I'll also do some resets of my Batt Monitoring....to see what's being put in vs out...will re-sync the BVM as it was setup when batteries were new...if they are indeed toast the BVM will probably give out difference readings...

        I'll check into the 6Volt option...will need to find ones that fit into my battery compartment...

        Thanks again and just wanted to confirm that its on the battery side vs controller side...
        Brian

        Comment


        • #5
          Originally posted by Bluwavguy View Post

          I'll do some reseach on the sulfate battery issue...as the rise in voltage occurs momentarily...they will be sitting happy at 13.5...assume while the controllers (recently installed a 400w wind generator with it's own controller) are in float state...and then I'll notice (if I have my inverter running as the fan will increase it's rpm) the increase to 16 or just above and this lasts only a few seconds...then batt voltage will drop down to the mid 13's....
          Wait... the batteries are being charged by a wind controller *and* a PV controller? Depending on how each of them sets its PWM (or on-off) duty cycle, it is possible that more current than necessary is being fed to the battery, since each controller thinks it needs to float them on its own and is unaware of the charge the other is producing. When in float, try shutting one of the controllers down completely and see if the high voltage problem goes away.
          CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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          • #6
            Hi sensij, issue was on-going well before I installed the wind generator. BTW! I contacted both CO's (MorningStar and Coleman) confirming the potential issue and both CO's said no problems will occur.

            The over voltage is only occurring during peak sunlight hours (in the Caribbean from about 11am-4pm). When in float the wind generator will auto-break and not rotate. Both controllers are set at about 14.2vdc. (Will install a amp/Volt meter in the coming days for the wind gen next to the solar monitor).

            In review of Sunking's post I am not convinced my batts are toast. I've never seen them below 12.5VDC (70%SOC) and rarely below 12.6VDC (80%SOC). For most of of the time my batts have been @ 100%SOC unless I'm on board using systems during the day (but even then SOC is at 99.9%) and during night time hours is when the SOC drops into the low 90's. ( I may have incorrectly stated 85% SOC and the brief time to reach 100% SOC on my original post. )

            In brief research sulfation occurs when SOC drops below 60% or more SOC and not rapidly recharged. I'm not versed on all variants of the
            issue but seems that if the batteries are constantly being charged and maintain a high SOC, which mine have been, sulfation may not be the real issue.



            Comment


            • #7
              There are only two ways for the batteries to go to 16 volts. A [U][B]faulty charger or bad batteries[/B][/U]. It has to be one of the two. Also make sure your connections are good and tight as a poor connection can fake your meters out. If your Inverter is alarming high voltage, connections are likely OK. Bad Connections on the Inverter will be low voltage.

              A simple load test wil determine if it is the batteries. Disconnect the panels and put a heavy load on the batteries. Watch the voltage for some time with a heavy load. If the voltage holds, they are good. If the batteries are good, then you have a bad controller failing to shut off and regulate the voltage cooking the batteries. Taking AGM's up to 16 volts is one heck of an over charge.

              Tip. Make sure you are measuring the voltage directly on the battery Term Post, all 3 of them. They are must be equal, or you have a connection issue.
              Last edited by Sunking; 05-31-2017, 08:51 PM.
              MSEE, PE

              Comment


              • #8
                Sunking, disconnected solar to observe batteries and left the wind generator on-line. What was interesting is to watch the generator supply power up-to 14.4VDC before it shut down. It has a built in break which prevents the turbine from spinning when it senses the batteries are fully charged.

                Later today, as I need to leave my boat, I'll disconnect the generator from the system to see how the batteries behave.

                What I can determine, as this is my 2nd controller from Morningstar as they recently sent a replacement due to the issue of the over-voltages, it does this when it's being powered up via the panels, it goes into the high-voltage state of 16.5VDC for a very brief period of time as observed again today. Yesterday I notices the controller shut down and the status LED turned on for about 5 min then cleared. Today the controller did nothing even though it's monitor showed 14.0VDC and the batteries where at 16.5VDC (checked with a DVM and also from the Victron).

                Now perhaps the batteries are bad but what is the controller doing? I want to reach out to Morningstar again but looking for a definitive issue to give them...

                BTW all connections are tight.

                Thank you, Brian

                Comment


                • #9
                  Could this be an issue with Equalization Charge Mode?
                  That is another reason for 16.5 Volts.
                  Can you DISABLE EQ, just to see if your problem goes away?

                  P.S.
                  I just saw that you wrote this ...
                  [I][B]The Controller is measuring only 14.0 Volts but yet you are measuring 16.5 Volts at the battery.[/B][/I]
                  So, the Controller has a Voltage Measuring problem?
                  How (where) does the Controller measure Battery Voltage?
                  a) At the Controllers Terminals ?
                  b) Remote Sense at the Battery's Terminal ?

                  And [B]both[/B] MorningStar Controllers ( old & new ) have the same issue?
                  Corrosion or bad connection somewhere?

                  Is there a Shore Power Charger than can be doing EQ?

                  Sulfation may have already occurred in your 3.5 year old batteries.
                  Fully charge the batteries
                  Remove the Battery Pack
                  Remove the interconnecting cables.
                  Let the batteries rest for 24 hours with no load
                  Measure the Voltage of each battery and report back ...
                  Last edited by NEOH; 06-01-2017, 12:44 PM.

                  Comment


                  • #10
                    Neoh,
                    issue was occurring so I reached out to Morningstar and they sent me a replacement last week. So yes, both controllers set up identically are behaving the same. I'll need to be more diligent on the timing of the over voltage and duration. I do know the batts will be at 13.5 or in this range after a few hours of sun. Assume in float. I'll turn on the inverter to charge up iPhone or pad and after a while I'll hear the inverter fans accelerate and will walk over to see the BVM display showing voltages are going up and rapidly to a max of 16.6 or 16.7. By then I'll shut inverter down or it goes into auto shutdown. Then the voltages start going back to normal in the mid 13's. This all occurs in a matter of seconds.

                    On the voltages mentioned earlier. The controller monitor is direct connect to th controller so it's displaying the controller output. Now that may seem obviously a variable to remove from the issue if I can be sure the display voltage is the same as the output voltage? Something to further investigate as I can pull the output lead to the battery bank to isolate.

                    On the sulfation. I don't know the effects to the point where going from float to X mode the batteries start discharging a higher voltage due to what? If sulfation is an issue what's occuring chemically to increase voltages to 16.5 then stops? Now, since I'm on wind vs solar the inverter is running normally and has yet to shut down. Of course winds are light at the moment and batteries are sitting around 13vdc.

                    So so just turned on a bunch of systems and drawing about -9.5 constant for over 10 min. That's actual load current as well. Turned on high current pumps for 15-20 secs at a time. And saw batt voltages not going below 12.4 and now back to 12.7 after turning everything off. Sure my batts are old and not at 105ah but don't think they are toasted. I'd like to know what to expect the drop would be and where it should hold while loading them up given their age and I doubt they have ever gone that low before as I never have that much load on them without engine on or solar.

                    On the controller. Going from float to bulk dumps voltages back into the batteries. According to Morningstar's manual bulk state uses 100% of available solar.

                    On the disconnect and 24 wait. Hard to do that at the moment since I'm living aboard and running 12vdc Refridgeration.

                    Thanks Brian

                    Comment


                    • #11
                      It almost sounds like your controller is disconnecting and putting the solar panels into an open circuit state, if this happens in seconds.
                      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                      Comment


                      • #12
                        Originally posted by littleharbor View Post
                        It almost sounds like your controller is disconnecting and putting the solar panels into an open circuit state, if this happens in seconds.
                        Good point! Is the ~16 V reading indicating the PV voltage, or the battery voltage?
                        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                        Comment


                        • #13
                          Littleharbor,
                          what I am doing now is logging every 5 min the status of solar, batt, and SOC. What I want to see is the SOC go to 100% status of float, then controller going back to bulk...I believe its this phase transition that is creating the high voltage output...and yes its just for a few seconds...

                          Sensij, 16VDC is batt level voltage, PV's are at about 19.5vdc when this occurs.

                          Comment


                          • #14
                            I'd have to go back and re read. or ask. Are you showing high voltage only at the controller? Can you use a DVM to check battery voltage at the same instant your controller is reading high?
                            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                            Comment


                            • #15
                              Iittleharbor, I'm pulling my readings off of my Victron BVM which is connected via a 500A shunt to the batteries. In 5 min I'll have an hour of log readings each 5 min...I also have a MorningStar controller monitor..and pulling data from it too...

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