When you plug in your HP EliteBook 840 and the battery percentage just sits there, it's a frustrating roadblock. The problem could be with the physical charger and port, a software setting, or the battery itself. Let's walk through the most effective fixes to get you back to a full charge.
Check Your HP Power Adapter and Port
Start with the basics. Look over your power adapter's cable for any kinks, fraying, or damage. Make sure it's firmly plugged into the wall outlet and the laptop's charging port. The EliteBook 840 typically uses a USB-C or barrel-style connector, so check which one your model has. If you see an LED on the adapter, confirm it's lit when plugged in.
Perform a Full Restart
Shut down your laptop completely, don't just put it to sleep. Once it's fully off, press the power button to turn it back on while it's still plugged into the charger. This simple reboot can reset the laptop's power management controller and often clears up temporary glitches that prevent charging.
Run HP PC Hardware Diagnostics
Your EliteBook has built-in diagnostics. Restart the laptop and immediately press the F2 key repeatedly to launch HP PC Hardware Diagnostics. From there, you can run a system test, and more specifically, a battery test. This tool will check the battery's health and report if it's failing or if there's a hardware issue with the charging system.
Update Drivers with HP Support Assistant
Outdated or corrupt drivers can cause charging problems. Open the HP Support Assistant app that came pre-installed on your laptop. I'd start by checking for all recommended updates, especially for chipset, power management, and battery controllers. This app is great for enterprise driver management and ensures you get HP-vetted updates.
Check for a BIOS Update
BIOS updates from HP frequently include fixes for power management and charging circuitry. You can check for the latest BIOS through the HP Support Assistant or by visiting the official HP support site for your specific EliteBook 840 model. Be sure your laptop is plugged in during the update process and follow the instructions carefully.
Inspect Your Charging Port and Cable
Over time, the charging port can accumulate lint and dust, preventing a good connection. Gently use a can of compressed air or a wooden toothpick to clean out the port. Also, if you're using a USB-C charger, try a different port on the laptop, as not all USB-C ports may support charging, especially if you're connected to a docking station.
Review Power Settings and Battery Limits
Go to Settings > System > Power & battery. Some business laptops, including HP models, have battery conservation features that limit the maximum charge to extend battery lifespan. Check if a feature like "Maximize my battery health" or a custom charge limit is enabled and stopping the charge at 80%.
Reset the Battery Driver in Windows
Open the Device Manager and expand the Batteries section. Right-click on Microsoft ACPI-Compliant Control Method Battery and select Uninstall device. Do the same for any "Microsoft AC Adapter" listing. Restart your laptop. Windows will automatically reinstall fresh drivers upon reboot, which can resolve detection issues.
Test with a Different, Compatible Charger
If you can, try charging your EliteBook with a known-good, compatible power adapter. Adapters can fail or provide insufficient power. Make sure any replacement charger meets the laptop's power requirements. For many EliteBook 840 models, a 65W USB-C or HP smart adapter is standard. Using an underpowered charger might only run the laptop, not charge the battery.