One of the more common questions I hear is whether it is okay to leave your laptop plugged in all the time. Battery technology has changed over the years, resulting in some conflicting advice coming from friends and family around how to best charge that laptop, smartphone or tablet.
Most current portable devices have switched over to Lithium-ion batteries for power from older nickel-based battery technologies. One of the outdated tips given around the older NiCad batteries was to always fully discharge and recharge the batteries whenever possible. Partial charges, along with age and overcharging issues, meant shorter lives for NiCad batteries. The newer Lithium-ion battery technology has addressed many of these issues, so the advice around them has changed.
Lithium-ion Batteries and Charging Cycles
The first thing to understand about a Lithium-ion battery is that they are often rated in “charge cyclesâ€. A charge cycle can be considered a full discharge and recharge of the battery. If you let your MP3 player run until it turns off, then charge the battery back to 100%, you put the battery through a full charge cycle.
What happens if you partially charge a Lithium-ion battery? A partial charge only counts as a portion of the rated cycle charge lifespan. So, if you let that MP3 player fall from 100% to 50% one day, charge it back to 100% overnight, then do the same again the next day, you’ve actually only completed one charging cycle, even with two charges. If you only let your battery go from 100% to 80% every day, you could go 5 days before using a full charge cycle.
This means that, unlike older battery technologies, it’s not required to always let the battery discharge completely before plugging your device in for the night.
But What About Always Plugged In Laptops?
As battery technology has improved, so have the battery charging systems built into modern portable devices. The chargers are smarter than ever, and will do their best to avoid overcharging, and damaging, the battery as best they can.
However, it’s still a good idea to “exercise†your battery on a regular basis to keep the chemistry working inside the battery as designed. It’s okay to leave the laptop plugged in while working on a large project, but take the time to use that laptop unplugged on the couch or outside in order to give that battery some time to work on its own.
Another tip for your charging system is to “calibrate†the system once a month by allowing the battery to fully discharge, then recharge. This helps to make the measurements on how much battery life you have left more accurate, while also putting your battery through its charging cycle paces.
Other Tips on Battery Care
One of the other disadvantages to leaving your laptop plugged in all the time is that the battery is often exposed to more heat while the laptop is stationary. Many Lithium-ion batteries operate best within a 50°F to 95°F to temperature range. Make sure that you’re giving both your laptop, and its battery, plenty of room to “breatheâ€.
While it’s normally safe to discharge the battery to the point where the device turns off, be careful not to discharge the battery any further. This can result in a situation where the battery no longer charges correctly. If the device has powered down due to low battery charge, it is best to hook it up to a charger instead of trying to turn it back on to “eke out†a few more minutes of use.
If you need to store a device for an extended time, like a month long vacation away from that work laptop, it is best to charge the battery to 50% before leaving. Too much or too little charge can have negative long term effects on a battery that is left uncharged for extended periods.