Replace a Battery in a CB-Series Data Buoy

The 12V sealed lead acid batteries installed in the data well of CB-Series buoys may require replacement if their charge falls below ~10V or every 2-3 years as their integrity declines with age. This article highlights the basic steps required to replace the A05 12V 28 A-Hr battery commonly equipped in quantities of 1 to 3 on the NexSens CB-450, CB-650, CB-950, and CB-1250 data buoys.

Caution- While assembling the battery harness insulate any loose battery leads, wrenches or other tools with electrical tape to avoid shorting out the batteries against the data well and potentially causing injury.

Tools Required

  • Electrical Tape
  • 9/16″ Socket Wrench with extension
  • 10mm Socket Wrench with extension
  • Fully Charged Replacement Battery
  • Digital Voltmeter
  • New Desiccant (recommended)

Battery Removal

  1. Disconnect the 6-pin solar panel cable from the X2-CB’s SOLAR port to remove power to the data logger.
  2. Remove the buoy’s solar tower to gain access to the data well
    1. For the CB-450: Remove the (6) 3/8-16×3/4 bolts and 3/8 lock washers holding the solar tower to the buoy using a 9/16 socket wrench.
    2. For the CB-650, 950, and 1250: Remove the three clevis pins securing the solar panel tower legs to the buoy hubs and carefully lift upwards to detatch the assembly.

      Remove the solar tower from the buoy to access the data logger.

  3. Remove the (8) 3/4 bolts and 3/8 lock washers  from the buoy plate using a 9/16 socket wrench.

    Removing an X2-CB to access the buoy data well


  4. Lift the buoy plate off of the data well.  Disconnect the 6-pin UW-plug running between the solar regulator and the X2-CB. This will expose the data well where the battery and solar regulator are installed.

    Top-view of a CB-series data well showing the UW-6 solar regulator cable.


  5. Remove the small, then large diameter foam covering the battery harness

    Top-view of the solar regulator and battery assembly with the protective foam pieces removed.


  6. Remove the 3/8″ nut, lock washer and flat washer securing the regulator bracket to the battery.
  7. Use a 10mm socket wrench to remove the regulator’s ring terminals from the battery. Set aside the terminal bolts for use later.
  8. Lift the regulator bracket off of the threaded rod and remove it from the data well.
    1. The battery should now be accessible.

[Only for systems with 2 or more batteries]

  1. Carefully remove one of the two ring terminal cables connected to the battery using a 10mm socket wrench. Immediately cover the loose cable end with electrical tape to prevent it from contacting the data well.
    1. Repeat this step for the other battery terminal and cable, removing the old batteries one by one as they are free.
  2. Remove the used battery from the data well. It may be necessary to remove some of the wedged foam surrounding it in the event it does not easily lift out.
  3. Remove the ring terminal cables from the original battery terminals using a 10mm socket wrench. Keep the terminal bolts and re-use them in the new battery.

New Battery Installation

  1. [For systems with a single battery]
    1. Lower the new battery into the data well. It may be necessary to adjust the foam for a proper fit.
    2. Skip ahead to Step 3 “For All Systems”
  2. [Only for systems with 2 or more batteries]
    1. Discard any pre-installed hardware on the new battery terminals. Using the original  battery terminal bolts and a 10mm socket wrench, tighten the ring terminal cables to the new battery.
    2. Make sure that the cables point toward the corners of the battery.

      If more than one A05 is installed, be sure to align the ring terminal cables as shown in the picture. Always insulate the detatched cable leads to prevent shorting out the battery during installation.


    3. Ensure that the opposite ends of the ring terminal cables are still insulated with electrical tape.
    4. All batteries except the top-most should have neoprene strips adhered in line with the terminals to maintain spacing as shown in the picture above.
    5. Lower the first battery into the bottom of the data well. Stack the second, then third battery (if applicable) attaching the previous battery’s ring terminal cable to the corresponding battery terminal above it.
  3. [For all Systems]
    1. Once the final battery is installed in the data well, orient the solar regulator bracket so that the ring terminal connections to the top-most battery are on the same side.
    2. Slide the solar regulator bracket back on to the threaded rod and lower it until it is resting on top of the new battery.
    3. Tighten down each ring terminal from the solar regulator to its corresponding battery terminal using a 10mm socket wrench.

      After tightening down the solar regulator ring terminal leads to the A05 battery, make sure the leads face inwards towards the center of the battery as shown


    4. Place the 3/8″ flat washer, followed by the 3/8″ lock washer and 3/8″ nut over the threaded rod and hand tighten the regulator bracket to the top battery.

      Hand-tighten the solar regulator bracket to the top A05 battery using the original mounting hardware


    5.  Using a 9/16″ socket wrench, tighten down the regulator bracket until it is snug. Do not over-tighten as this may bow or crack the regulator bracket.
    6. Return the large diameter, followed by the small diameter foam to the data well. Feed the 6-pin solar plug through the hole in the small diameter foam.

Buoy Plate Re-installation

It is recommended that new desiccant be added at this point in the process.

  1. Reconnect the solar plug to the receptacle at the bottom of the X2-CB.
  2. Align the X2-CB or pass-through plate with the mounting holes on the buoy and verify that the large o-ring is in good condition and clear of debris.
  3. Re-attach the plate using a 9/16″ socket wrench and the original 3/4 bolts and 3/8 lock washers, tightening in a cross-pattern, as shown in Step 3 of the battery removal process.
  4. Re-attach the buoy solar panel.
  5. Using a voltmeter, measure the voltage between pins 3 (V+) and 4 (GND) of the X2-CB SOLAR port. This should read close to the voltage of the new battery (~12V to 15V). If the voltage is significantly less than the charge of the battery, verify that that the reassembly process was completed successfully.

    Verify Battery Voltage.


  6. Connect the 6-pin solar panel plug to the buoy’s SOLAR port to reapply power to the data logger.