Forum Discussion
Laptop Battery Replacement?
Have a Dell XPS 15 9520. Had this laptop for over 2.5 years and am still using the same battery. My laptop is plugged in almost always 100%. It is connected to 2 external monitors. Not only that, for quite some time, I have left my laptop. I just lock it at night. I have bitlocker as well.
The only time when my laptop is not plugged in is if I power off my laptop which is rare or if during the night, my UPS powers off by itself... the battery is bad but I'm using the UPS as a surge protector... so when in the morning, either my laptop is very low battery or it shut off by itself because the power went out of the UPS.
2 Replies
That behavior actually makes sense given how you’re using it.
Keeping the XPS plugged in at 100% almost all the time does accelerate battery wear, especially over 2+ years. Lithium-ion batteries age fastest when they’re:
Held at high charge (near 100%)
Kept warm (external monitors + constant power = more heat)
Rarely allowed to cycle
Locking the laptop overnight is fine, and BitLocker isn’t related, but when your UPS cuts power, the laptop suddenly has to rely on a battery that’s already degraded and sitting at a low effective capacity. That’s why it either drops to very low battery quickly or shuts off entirely.
A few points worth checking/doing:
In Dell BIOS / Dell Power Manager, set a charge limit (e.g. max 80%). This helps a lot going forward.
Run a battery health check (powercfg /batteryreport in Windows or Dell diagnostics) — it will likely show significant wear.
If you keep using a UPS mainly as a surge protector, consider replacing the UPS battery so it doesn’t randomly cut power.
At 2.5 years with this usage pattern, needing a battery replacement is normal, not a defect.
In short: nothing unusual or BitLocker-related here — it’s just a worn battery finally being exposed when AC power drops.1. Safety preparation steps
Turn off the computer and disconnect the power:
Turn off the computer → Unplug the power cord
Press and hold the power button for 30 seconds to release residual current
2. Anti-static measures:
Use an anti-static bracelet
or touch a metal surface to discharge the electricity
3. Quickly identify the battery model
Check the battery information by command:
powershell
powercfg /batteryreport
Report path: C:\Windows\System32\battery-report.html
Key Information: DESIGN CAPACITY, BATTERY ID
4. Physical check (for removable batteries)
Flip the notebook over to view the battery compartment
Look for similar code: L18M3PG (Lenovo) / 02DL001 (Dell)
5. Calibration steps after replacement
Fully charged: Connect to power source until 100%.
Deep Discharge:
Unplug the power supply → Use until automatic shutdown
Leave for 2 hours
Recharge fully:
Charge to 100% without interruption
Press Win + X → Terminal (Administrator) → Execute:
powershell
powercfg /batterysaver on
