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  • #16
    Originally posted by Danny_DK View Post

    Hi SunEagle,

    During my calculations I did account for charge and wire losses but you may be onto something regarding the little sunlight. During testing it was installed along a build which is blocking the sun light hitting the PV panel until the afternoon. This would have an effect on the charging of the battery.

    With the 20W panel I currently the VMP is 17.5VDC and IMP is 1.15A. This is within what you say about the charge rate. I though the battery and PV panel was sized ok for such a small system and with the components available at the time.

    The Charge Controller was something I was unsure about. I will look into a PWM C/C and see what I can find. So sourcing a 10AH C/C should be ok for charging the 10AH battery or should I go for smaller battery? I don't really like to increase the size of the solar array itself.
    You are probably on the right track. Without the correct intensity and duration of sunlight a pv panel just won't produce what is expected. Hopefully you can find a way to get more sunlight on that panel but what also works when you don't have enough sun is to use more panel wattage. Not efficient but it might help keep your battery happy.

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    • #17
      Hi All,

      Thank for your help with some changes this seemed to have help the charging process.

      However now another issue has come up.

      I have being checking the battery level etc each day to make sure all is sound but noticed the voltage level of the battery is in the 16V mark?? From a 12V battery this doesn't seem right to me? 14 or 15 V is more what I was thinking from the fully charged battery. The charge controller says the battery is charged fully (this is a 12V charge controller as well), Anyone come across this before??

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      • #18
        Originally posted by Danny_DK View Post
        Hi All,

        Thank for your help with some changes this seemed to have help the charging process.

        However now another issue has come up.

        I have being checking the battery level etc each day to make sure all is sound but noticed the voltage level of the battery is in the 16V mark?? From a 12V battery this doesn't seem right to me? 14 or 15 V is more what I was thinking from the fully charged battery. The charge controller says the battery is charged fully (this is a 12V charge controller as well), Anyone come across this before??
        Have you checked your volt meter on a different DC source to see if it is reading correctly?

        You really should never see 16volt on a 12volt battery even when it is being charged unless the charger settings are incorrect.

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        • #19
          Yes I did check it all out on different source, think i was seeing thing I remeasured the battery again and it was the same. I disconnected connection and measured them on there own. Measuring the battery on it own (not connected to the charge controller) the voltage is 14V which is what i expect. Connecting the PV input increased this to 16V _-----Strange??

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          • #20
            I would agree that getting 16v from the charge controller to the battery is a little high.

            Remember to first connect the CC to the battery and then connect the pv panels to the CC. Most CC need to know what the battery voltage is before they start to work properly.

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            • #21
              are you measuring the voltage at the battery's lead terminals, or on the wires at the charge controller ? Sometimes insufficient wiring can give erroneous voltages.
              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

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              • #22
                Originally posted by SunEagle View Post
                I would agree that getting 16v from the charge controller to the battery is a little high.

                Remember to first connect the CC to the battery and then connect the pv panels to the CC. Most CC need to know what the battery voltage is before they start to work properly.

                I actually double checked all this before deploying the system. It is quite strange to see that voltage tho. I wonder has a something happened that affected the charge state. Have you every came across this before?

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                • #23
                  Originally posted by Mike90250 View Post
                  are you measuring the voltage at the battery's lead terminals, or on the wires at the charge controller ? Sometimes insufficient wiring can give erroneous voltages.

                  I was measuring that the point on the C/C and then measured at the battery and was the same. Once I disconnected the PV panel the voltage dropped down to more what I expected. Seems very strange to me it would appear the C/C does not shutdown when the battery is at full capacity?

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                  • #24
                    It is possible that the charger is being fooled in thinking the battery needs that higher voltage or there is something wrong with its charging control system.

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                    • #25
                      Originally posted by SunEagle View Post
                      It is possible that the charger is being fooled in thinking the battery needs that higher voltage or there is something wrong with its charging control system.

                      Hi SunEagle,

                      I dont think its the charged fooled in thinking that, I know some chargers work of 12V and 24V which is internally selected. However this is only a 12V C/C so it would maybe look like a C/C problem itself

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                      • #26
                        Originally posted by Danny_DK View Post


                        Hi SunEagle,

                        I dont think its the charged fooled in thinking that, I know some chargers work of 12V and 24V which is internally selected. However this is only a 12V C/C so it would maybe look like a C/C problem itself
                        That is the only conclusion that can be made. Sounds like it failed Closed aka Shorted. The FET is shorted and is extremely easy to determine with a simple volt meter check. Just measure the input voltage from the panels, and the output voltage of the controller. If they are roughly equal, within one volt, it is shorted, or at 100% modulation. .

                        A PWM controller is nothing more than an Off/On switch that operates at very high frequency. PWM means Pulse Width Modulation. When modulated to 100% connects the panel to the battery. At 0% modulation is an open circuit.

                        On the Input side of the Controller the voltage range can be anywhere from Panel Voc of roughly 22 volts at 0% modulation when the battery is fully charged, and down to Battery Voltage at 100% modulation when full power is being supplied to charge the battery. Well at night 0 volts. But if you see 16 volts on the Input, and roughly 16 volts on the battery, your controller has shorted out and has connected the Panel Directly to the battery and severely over charged it.

                        To confirm wait till dark and measure the Controller input Voltage. It should be ZERO. If it reads about the same as the battery, replace it. Easy Peazy to test.
                        Last edited by Sunking; 03-03-2016, 04:02 PM.
                        MSEE, PE

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                        • #27
                          < 2% per month at 25ºC
                          Can any one tell me what does it means? If i am calculating battery bank what figure should i use for Depth of Discharge. help me out plz

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                          • #28
                            Originally posted by Sunking View Post

                            That is the only conclusion that can be made. Sounds like it failed Closed aka Shorted. The FET is shorted and is extremely easy to determine with a simple volt meter check. Just measure the input voltage from the panels, and the output voltage of the controller. If they are roughly equal, within one volt, it is shorted, or at 100% modulation. .

                            A PWM controller is nothing more than an Off/On switch that operates at very high frequency. PWM means Pulse Width Modulation. When modulated to 100% connects the panel to the battery. At 0% modulation is an open circuit.

                            On the Input side of the Controller the voltage range can be anywhere from Panel Voc of roughly 22 volts at 0% modulation when the battery is fully charged, and down to Battery Voltage at 100% modulation when full power is being supplied to charge the battery. Well at night 0 volts. But if you see 16 volts on the Input, and roughly 16 volts on the battery, your controller has shorted out and has connected the Panel Directly to the battery and severely over charged it.

                            To confirm wait till dark and measure the Controller input Voltage. It should be ZERO. If it reads about the same as the battery, replace it. Easy Peazy to test.

                            Hi SunKing,

                            Thank you for your help.

                            It looks like you are correct yet. Measured the battery voltage with PV panel connected, both were within a volt of each other. I think it is because of a due. What would be the cause? Could it be a inrush of current from the PV or a backrush of current from the battery?

                            Taking your info of testing the system in the dark, I did a quicker test of disconnecting the PV panel this should give 0V at the input (in my thinking) however am getting about half the battery voltage i.e batt voltage 12V the pv input is approx 6V. Think this verfies your thinking to me.

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                            • #29
                              Originally posted by Danny_DK View Post
                              Taking your info of testing the system in the dark, I did a quicker test of disconnecting the PV panel this should give 0V at the input (in my thinking) however am getting about half the battery voltage i.e batt voltage 12V the pv input is approx 6V. Think this verfies your thinking to me.
                              I concur.
                              MSEE, PE

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                              • #30
                                Danny - what is the model / make of your charge controller?

                                And the most crucial of all - how much power is your gprs module drawing per hour? Does it run 24/7?

                                Note that your ups-style little agm battery is likely fried by now with 16v hitting it. Game over. What is the make / model of that, and did you start with a new one, or is this something used pulled from something else...

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