charging issue

[sumair_hussain0]

Title: HP EliteBook 840 G2 shows "Plugged in" but charging LED turns on and off intermittently

Hello everyone,

I'm having a charging issue with my HP EliteBook 840 G2.

When I connect the charger, Windows detects it and shows "Plugged in." However, the charging LED near the charging port does not stay on consistently.

Sometimes the charging LED turns on for about 30 seconds, then turns off for about 30 seconds, and this cycle keeps repeating. During this time, Windows still shows that the charger is connected.

I'm not sure whether the battery is actually charging properly when the LED turns off.

Could this be caused by:

• A faulty AC adapter?

• A failing battery?

• A loose or damaged charging port?

• A motherboard/charging circuit issue?

What tests can I perform to determine which component is causing the problem?

Any help would be greatly appreciated. Thank you!

[haythamkha]

Hi,

The LED cycling on and off does not automatically mean the motherboard is faulty. HP explains that the battery/adapter light behavior can change depending on the battery charge level. In some cases, the battery light may turn off when the battery is already above a certain charge level, because the notebook may not start charging again until the battery drops below the charging threshold:

https://support.hp.com/us-en/document/ish_9583671-9583770-16

However, if the LED repeatedly turns on for around 30 seconds and then turns off again while Windows still shows “Plugged in,” I would troubleshoot the power path step by step.

First, test with a known-good genuine HP Smart AC adapter. A weak, non-genuine, or incorrect-wattage adapter can cause unstable charging behavior. HP’s AC adapter troubleshooting guide explains how to test the adapter using HP PC Hardware Diagnostics:

https://support.hp.com/us-en/document/ish_2025983-1502949-16

Second, run HP PC Hardware Diagnostics:

1. Turn off the laptop.
2. Turn it on and press Esc repeatedly.
3. Press F2 for HP PC Hardware Diagnostics.
4. Run the Battery Test and, if available, the AC Adapter Test.

HP’s official hardware diagnostics page:

https://support.hp.com/us-en/help/hp-pc-hardware-diagnostics

HP Battery Check / battery charging troubleshooting:

https://support.hp.com/us-en/help/computer/battery-adapter-issues

Third, perform a power reset. HP recommends this as an early troubleshooting step for power and charging issues:

https://support.hp.com/us-en/document/ish_1997208-1551050-16

Steps:

1. Shut down the laptop.
2. Disconnect the AC adapter.
3. Remove or disconnect the battery if it is safe and accessible.
4. Hold the power button for 30 seconds.
5. Reconnect the AC adapter and test again.

Fourth, check the charging connector carefully. If the LED changes when you slightly move the charger plug, the issue may be a loose DC jack, damaged adapter tip, or DC-in cable.

My suggested conclusion:

• If another genuine HP adapter works normally, replace the adapter.
• If the HP Battery Test fails, replace the battery.
• If both adapter and battery tests pass but the LED still cycles, the likely cause is the DC-in jack/cable or the motherboard charging circuit.
• I would avoid updating the BIOS while the charging connection is unstable, because losing power during a BIOS update can cause a more serious issue.