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  • Troubleshooting Batteries Tutorial

    Before testing, follow these steps:


    • Check that all vent caps are secured properly on the battery.
    • Clean the top of the battery, terminals and connections with a cloth or brush and a solution of sodium bicarbonate solution. Do not allow cleaning solution to get inside the battery. Rinse with water and dry with a clean cloth.
    • Check battery cables and connections, replace any damaged cables and tighten any loose connections.
    • Check the electrolyte level in FLA batteries and add distilled water if necessary.
    • Fully charge batteries before conducting any tests.


    Specific Gravity Testing

    Equipment needed:

    Hydrometer, Battery Maintenance log book, Rubber gloves, Goggles, Apron, Sodium Bicarbonate Solution, and Distilled Water.

    A specific gravity reading is the most accurate way to determine a battery’s state of charge. This measurement is based on the density of the electrolyte compared to the density of water and is typically determined by the use of a hydrometer. The specific gravity of water is 1.000 and the specific gravity of the sulfuric acid electrolyte in a typically fully charged Industrial battery is 1.260. Specific gravity measurements are used to determine if the battery is fully charged or if the battery has a weak or a bad cell. A high specific gravity means a higher density of acid to water, which normally indicates a higher state of charge. Specific gravity should be measured when the battery is not under a load and should not be measured soon after water is added to the battery. A good hydrometer to use is Freas Glass works Number 99 hydrometer. Wear eye protection, rubber gloves and have sodium bicarbonate solution and water on hand in case of acid spills. To find the specific gravity of your battery’s cells, follow these steps:

    • Use a hydrometer that measures within five grading points or less
    • Fill and drain the hydrometer with electrolyte two-three times before drawing a sample from the battery.
    • Take a sample of the electrolyte. The sample must be large enough to completely support the float. Hold the hydrometer in a vertical position so the float is not touching the sides, top, or bottom of the tube. Look straight across the electrolyte level to read the float as shown above.
    • Record the specific gravity readings for all battery cells on your Battery Maintenance Log Sheet.
    • Correct the specific gravity readings for temperature by adding 0.004 for every 10°F (5°C) above 80°F (27°C) and subtract 0.004 for every 10°F (5°C) below 80°F (27°C).
    • If every cell in the battery bank is below 1.260, the batteries are undercharged; recharge batteries.
    • If any battery has a specific gravity variation of more than 0.050 between cells, equalize the battery bank.
    • If there is still a variation of more than 0.050 between cells after equalizing, it may indicate a failed battery.
    • After testing, rinse the hydrometer out with fresh water at least five times to flush the acid out.


    On-Charge Voltage Testing

    Equipment needed:

    Voltmeter or Multi-Meter, Battery Maintenance Log Sheet, Rubber Gloves, Goggles, and Apron

    On-charge voltage testing is a secondary test to verify that there is a problem if the specific gravity test indicates something was wrong. An on-charge voltage test is done while connected to the controller and the battery is charging. This test indicates if the charge controller is working properly. Proceed as follows:

    • Disconnect and reconnect the DC power source (Panels) to the charge controller to restart the charge controller manually if required.
    • While the batteries are on charge (not float charging) record the current in the last ½ hour of Absorb charge (if possible) and measure the battery bank voltage.
    • While the batteries are on-charge measure the individual battery voltages with a voltmeter. If any battery voltage is below: 2.33V for 2V, 4.66V for a 4V, or 7.0V for 6V battery, and a voltage variation is greater than 0.17V for a 2V battery, 0.33V for a 4V battery, 0.5V for 6V battery, from one battery to another in a set, it may indicate a failed battery.
    • Record data on the Battery Maintenance Log Sheet for warranty. Determine if there is a bad battery in the set – replace if necessary.
    • If any battery voltage variation is greater than 0.33V for 2V, 0.47V for 4V, or 0.7V for 6V battery from any other battery in the battery bank, equalize the battery bank. After equalizing the battery bank, re-measure the individual battery voltages. If any battery voltage variation is still greater than 0.33V, 0.47V or 0.7V respectively, from any other battery in the battery bank, you may have a failed battery.


    Open Circuit Voltage Testing

    Equipment needed:

    Voltmeter or Multi-Meter, Battery Maintenance Log Sheet, Rubber Gloves, Goggles, and Apron.

    Open circuit voltage testing is used to determine the battery’s state of charge, however it is not as accurate as a specific gravity test, which measures each battery cell. The test is done when the load is disconnected to the battery. Proceed as follows:
    • For accurate voltage readings, batteries must remain idle (disconnected for the power source and the load) at least 6 hours, but preferably up to 24 hours.
    • Measure the individual battery voltages with a voltmeter.
    • If the battery voltage difference is 0.33V for 2V, 0.47V for 4V, or 0.7V for 6V greater than the other batteries in battery bank, equalize the battery bank. After equalizing the battery bank, re-measure the individual battery voltages. If any individual battery voltage is 0.33V for 2V, 0.47V for 4V, or 0.7V for 6V lower than any other battery in the battery bank, you may have a failed battery.
    • If the battery voltage is not greater than 0.3V than any other battery in the battery bank, no problem is indicated.
    • Record data on the Battery Maintenance Log Sheet for warranty.
    MSEE, PE

  • #2
    Originally posted by Sunking View Post
    the specific gravity of the sulfuric acid electrolyte in a typically fully charged Industrial battery is 1.260.
    <snip>
    • If every cell in the battery bank is below 1.230, the batteries may be undercharged; recharge batteries.
    Wouldn't SG below 1.260 be undercharged? Is the "1.230" a typo?

    Originally posted by Sunking View Post
    An on-charge voltage test is done when there is a load connected to the battery.
    What load? Are you considering the charge controller to be a load?

    Originally posted by Sunking View Post
    Disconnect and reconnect the DC power source to the charge controller to restart the charge controller manually if required.
    OK, but many (most?) charge controllers should have the PV disconnected before disconnecting the battery, and then the PV should be reconnected after reconnecting the battery.

    --mapmaker
    ob 3524, FM60, ePanel, 4 L16, 4 x 235 watt panels

    Comment


    • #3
      Originally posted by mapmaker View Post
      Wouldn't SG below 1.260 be undercharged? Is the "1.230" a typo?
      Typo, corrected text.

      Originally posted by mapmaker View Post
      What load? Are you considering the charge controller to be a load?
      Edited to clarify.

      Originally posted by mapmaker View Post
      OK, but many (most?) charge controllers should have the PV disconnected before disconnecting the battery, and then the PV should be reconnected after reconnecting the battery.
      The DC power source is the Panels, batteries are storage. Again edited text to clarify.
      MSEE, PE

      Comment


      • #4
        For anyone unaware - this is meant as satire for a laugh - not real advice.

        Testing batteries the "South African way"

        1) Ensure the batteries are fully charged
        2) Disconnect from charger and any external load and allow the batteries to rest for at least 8 hours.
        3) Get two lengths of battery cable (minimum AWG 1, but preferably AWG 0000) at least 5m in length.
        4) Strip off about 2cm insulation from the cable ends
        5) Ensuring the cable ends are lying a safe distance from each other attach one end of each individual cable securely the positive and negative terminal of the battery.
        6) Approach the other ends of the cable carefully and grab a firm hold.
        7) Have a friend stand by with a pair of heavy duty cutters.
        7) Ram the bare ends firmly into a solid piece of metal.
        8) If the batteries are in good condition the arc should be very impressive, cables should react sharply (like a hose reacts to being pressurised) and should warm rapidly. At this point your friend needs to react quickly with the heavy duty cutters and sever one of the cables to break the circuit.
        9) If the results aren't very impressive the batteries are probably toast.
        10) Protective clothing and welding glasses are advisable for this test but not mandatory for South Africans
        Last edited by russ; 07-07-2014, 12:18 PM. Reason: added caution

        Comment


        • #5
          Originally posted by Dave3011 View Post
          Testing batteries the "South African way"
          Sounds like the 4th of July fireworks display - a short one at least!
          Last edited by inetdog; 07-07-2014, 02:31 AM.
          [SIGPIC][/SIGPIC]

          Comment


          • #6
            I just hope that readers of this thread are smart enough to realize that Dave's post is satire and should not really be tried.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

            Comment


            • #7
              Originally posted by inetdog View Post
              I just hope that readers of this thread are smart enough to realize that Dave's post is satire and should not really be tried.
              To confirm yes it is satire and should not be attempted by anyone who values their life or their equipment.

              Comment


              • #8
                Originally posted by Dave3011 View Post
                Testing batteries the "South African way"




                Haha.....I am sure you will get someone who will want to try that now....!! <--- (NB for any new people to solar reading this thread, as said above,...this was satire!! Dont try it...)
                Last edited by russ; 07-07-2014, 12:17 PM. Reason: shortened

                Comment


                • #9
                  That is some good information there Derick!

                  Is there any chance the mods could lock the thread...just so that it doesn't fill up with too many comments (which would more than likely just distract from your post)? This could even be sticky material for the batteries section (a good companion to your battery guides!)!

                  Comment


                  • #10
                    Originally posted by daz View Post
                    That is some good information there Derick!

                    Is there any chance the mods could lock the thread...just so that it doesn't fill up with too many comments (which would more than likely just distract from your post)? This could even be sticky material for the batteries section (a good companion to your battery guides!)!
                    I agree that what Derick wrote is good information and that the thread should be turned into a "sticky" but the satire by Dave should be modified, highlighted with major warnings or removed so someone with little to no brain cells doesn't try it.

                    Comment


                    • #11
                      Restored.
                      MSEE, PE

                      Comment


                      • #12
                        Thread Closed.

                        I have moved the most recent troubleshooting request to its own thread and closed this one for now.
                        SunnyBoy 3000 US, 18 BP Solar 175B panels.

                        Comment

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