HP EliteBook 840 G6 RTC battery replacement

Step-by-step HP EliteBook 840 G6 RTC battery replacement paraphrased from HP's official Maintenance and Service Guide, with page citations.

Source: paraphrased from HP's official Maintenance and Service Guide (PDF, printed pages 32, 35, 37–38, 49–50, 54). Not bench-tested. We have not performed this repair; keep HP's manual open for its illustrations. Scope restrictions below are part of the guide: do not apply it to other models, generations or configurations. Service manuals are written for trained technicians; work at your own risk.

Labels: DOCUMENTED = taken from HP's manual; PROPOSED = our own joining or ordering of HP's directions, not an HP instruction; UNPERFORMED = a suggested check that has not been carried out.

Applies to

HP EliteBook 840 G6. Confirm the exact model on the service label before starting.

Replace the OEM cabled RTC battery assembly as an intact service pack; no internal-cell dismantling or polarity/connector conversion.

RTC is in the authorized service provider chapter; target access/replacement is ASP-only. HP printed 37, PDF 47; HP printed 48, PDF 58

Assembly inventory and configuration

L17255-001 is the listed RTC battery assembly for this exact model. A shared spare in another model is not blanket compatibility evidence. HP printed 22, PDF 32; HP printed 54, PDF 64

Exact HP EliteBook 840 G6 and a verified like-for-like OEM assembly/configuration; preserve original routing and connector identity. Serial fit and regional eligibility remain unverified. Other models/generations, arbitrary substitutions and upgrades. No bare-cell substitution, pack dismantling, lead/polarity conversion, charging a primary cell or CMOS/password/firmware changes. HP printed 22, PDF 32; HP printed 54, PDF 64

Phillips P1; flat nonconductive, nonmarking release tool; grounded ESD workstation/strap. A nonconductive/nonmarking flat tool is an editorial selection where the RTC section says only flat tool. HP printed 32, PDF 42; HP printed 54, PDF 64

Documented facts and proposed boundaries

The documented service unit has a cable/plug and is removed intact. The procedure does not authorize opening its wrap, replacing an internal CR2032-like cell, changing lead polarity or attaching a generic coin cell. Basis: DOCUMENTED assembly/connector scope; PROPOSED substitution boundary. HP printed 54, PDF 64; HP printed 54, PDF 64

The illustrated RTC plug connects to the system board (callout 1); the tool release is callout 2 and pack lift is callout 3. The manual calls the seat a holder and uses a flat tool to pry the pack free. Basis: DOCUMENTED OEM text and applicable figure. HP printed 54, PDF 64; HP printed 54, PDF 64

No keyboard, radio antenna, speaker assembly, system-board or thermal-interface removal is an RTC prerequisite. Only the main-battery cable is disconnected; the main pack and its screws remain installed. Basis: DOCUMENTED OEM text and applicable figure. HP printed 54, PDF 64; HP printed 54, PDF 64; HP printed 49, PDF 59

Ordered replacement procedure

  1. prepare - Save work and shut down through the operating system. If power/hibernation state is uncertain, start normally and then shut down. Disconnect external devices and AC power before opening. Use a flat ESD-protected grounded work surface with a grounded wrist strap; avoid pins and circuitry and keep screws organized. Basis: DOCUMENTED shutdown/ESD precautions; PROPOSED organization join. HP printed 37, PDF 47; HP printed 35, PDF 45
  2. access - Turn the computer upside down. Loosen five ordinary captive screws and three inset captive screws (eight total). Start under the display at the upper-left corner, release the bottom cover and lift it away. Basis: DOCUMENTED OEM operation paraphrased. HP printed 37, PDF 47; HP printed 38, PDF 48
  3. isolate - Disconnect the main-battery cable at the system board, handling the connector rather than pulling its wires. Leave the battery pack and its retention screws installed: this target procedure calls for cable isolation only. Basis: DOCUMENTED OEM operation paraphrased. HP printed 49, PDF 59
  4. disconnect - Disconnect the RTC pack cable from its system-board socket (RTC figure callout 1), handling its plug rather than pulling on the wires. This is separate from the already isolated main battery. Basis: DOCUMENTED OEM operation paraphrased. HP printed 54, PDF 64; HP printed 54, PDF 64; HP printed 32, PDF 42
  5. remove - Use the flat tool at the holder’s illustrated release point (callout 2), free the intact RTC pack from the holder and lift it out at callout 3. Keep the pack, lead and connector together. Basis: DOCUMENTED OEM operation paraphrased. HP printed 54, PDF 64; HP printed 54, PDF 64
  6. install - Seat the matching L17255-001 intact RTC assembly in its original holder/recess and orientation by reversing removal. Keep its existing connector/lead arrangement; do not dismantle the pack or infer loose-cell polarity from the drawing. No RTC retaining screw, added adhesive type or torque is specified here. Basis: DOCUMENTED reverse installation expanded; PROPOSED intact-pack boundary. HP printed 54, PDF 64; HP printed 54, PDF 64
  7. reconnect - Route the RTC lead as originally installed and reconnect its matching plug to the system-board socket. Check that the pack is retained and the lead is clear of surrounding hardware without pulling, twisting or trapping it. Basis: DOCUMENTED reverse connection/cable-care rule; PROPOSED retention/routing check. HP printed 54, PDF 64; HP printed 54, PDF 64; HP printed 32, PDF 42
  8. restore - After checking target retention, connectors and cable routing and removing loose hardware, reconnect the main-battery cable to the system board. The main battery has not been removed. Basis: DOCUMENTED reverse battery procedure; PROPOSED inspection join. HP printed 49, PDF 59; HP printed 50, PDF 60
  9. close - Refit the bottom cover, engage its original edges and tighten its eight captive screws in their original locations. Reconnect external devices and AC only after the enclosure is secured. Basis: DOCUMENTED reverse-cover procedure; PROPOSED closed-unit restoration join. HP printed 37, PDF 47; HP printed 38, PDF 48

Proposed checks and limits

UNPERFORMED PROPOSED editorial check after correct complete reassembly: observe ordinary closed-unit startup and the displayed date/time without changing firmware settings. This is not a replacement interval, diagnosis or password-reset claim.

Part numbers in our catalog

Check each part page for its source and variant notes before ordering.

Official manual

HP Maintenance and Service Guide (PDF, HP). Machine-readable copy: /api/guides/hp-elitebook-840-g6-rtc-battery