My laptop battery started swelling, so I removed it and now run the laptop directly from its charger. Do I need to leave the charger connected while the laptop is powered off, or can I unplug it to reduce standby electricity use? I'm worried that disconnecting power might reset the system clock or erase BIOS settings.
3 Answers
The BIOS settings and clock are normally maintained by a small CMOS/RTC battery on the motherboard, so removing external power shouldn’t immediately erase them. If that battery is dead or nearly depleted, the clock may reset, but the operating system will often correct the time automatically after connecting to the internet. The laptop may also warn you during startup if the clock is wrong.
Check the charger’s standby draw if you’re curious, but an unplugged laptop charger generally consumes around a watt or less when the computer is off. Heating, cooling, water heaters, and other large appliances are much more likely to cause a significant bill increase. Also, don’t reinstall or continue using a swollen battery; replace it through a proper recycling or repair service.
You can safely unplug the charger once the laptop has completely shut down. Make sure it isn’t merely sleeping or hibernating—wait until the fans stop and all indicator lights are off. When you want to use it again, reconnect the charger before turning it on. Leaving the adapter plugged in while the laptop is off usually uses very little power, so it’s unlikely to explain a noticeable increase in your electricity bill.
A failing CMOS battery usually isn’t an emergency, but unexpected restarts during updates could cause problems if the machine loses its saved firmware settings. It’s best to replace the battery if the clock repeatedly resets.