Replacing QBR101C with BMU801 - LT31

Replacing QBR101C with BMU801 Spare Part Instruction
Document code
M213160EN
Revision
A
Language
English
Product
LT31
Document type
Spare part manual
This document describes how to replace the battery regulator QBR101C with the battery management unit BMU801 spare part (BMU801LTSP). BMU801 is fully compatible with all LT31 versions.
1
Battery cover
2
Cable channel
3
DC switch
4
QBR101C
5
End bracket
The BMU801LTSP spare part package includes:
  • BMU801 battery management unit
  • Cable set: battery cable and DC out cable
  • Connector for DC in cable
  • Cable ties (4 pcs)

You also need:

  • Flat head screwdrivers, 2.5 mm and 4 mm
  • Allen key, 3 mm
  • Wire cutters
WARNING Only licensed experts may install electrical components. They must adhere to local and state legislation and regulations.
WARNING Make sure that you prepare or connect only de-energized wires.
  1. Switch off LT31 AC (mains) power.
  2. Detach the battery cable connector from QBR101C.
  3. Open LT31 battery cover, unscrew the battery cover screws (4 pcs) with Allen key, and remove the battery and the battery cable.
    Dispose of the battery cable.
  4. Disconnect the wires from the connectors 1 and 3 of the DC switch and from the terminal strip.
    Dispose of the cable and the DC switch.
  5. Disconnect the wires from DC switch connectors 2 and 4 and the connector from QBR101C.
    Dispose of the wires.
  6. Detach the connector from QBR101C but keep the wires in the power supply FSP102 as they are.

    Do not remove the connector yet.

  7. Unscrew the end bracket.
  8. To remove QBR101C, bend it upward.
  9. To remove the DC switch, release a locking piece with a flat head screwdriver and lift it.
  10. Tear off the cable channel and dispose of it. Move the cables aside for now.

    The cable channel is glued to the interface box. After removing, some adhesive may remain on the surface.

  11. Reattach the end bracket in the new location.
  12. Make sure that the battery capacity rotary switch on top of BMU801 points to 1.

    Incorrect selection can cause damage to the battery and prevent or limit operation.

  13. Connect cable CBL211400 to BMU801 DC out port and the black wire to the 24 VDC connector 3 and the red wire to connector 4.
    BMU801 front and bottom view
    1
    DC in connector
    2
    Batt 1 connector
    3
    DC out connector
  14. Mount BMU801 on the DIN rail next to the end bracket.
  15. Replace the old DC in connector of the power supply cable with the connector included in the spare part set.
    Connector included in spare part set
    Make sure you connect the red wire to + and the black wire to -.
  16. Connect the power supply cable to BMU801 DC in connector.
  17. Connect the BMU801 battery wire from Batt 1 on BMU801 and the red wire to the + and the black wire to the - connector on LT31 battery, and put the battery in place.
  18. Put the battery cover in place and tighten the screws (4 pcs) with Allen key.
    Make sure that the cable does not get squeezed when you close the battery cover.
  19. Place the cables you removed from the cable channel above BMU801 and put a cable tie around them to keep them together.
  20. Switch on LT31 AC (mains) switch.
  21. Check that BMU801 powers up (the device status LED turns green). If not, press and hold the Power/Test button for 5 seconds.
    When you have connected BMU801 to LT31, make sure that you power up BMU801. If BMU801 is connected to LT31 but not powered up, LT31 measurement head does not receive any electricity.

For BMU801 documentation, see BMU801 documents on docs.vaisala.com.