Every phone and laptop battery loses capacity over time. That is chemistry, and nothing you do can stop it. What you can control is how fast it happens, and how much of each day's charge gets wasted on things you do not need. Small habits, mostly about heat and charging, can add a year or more of comfortable use before a battery needs replacing.
This guide is for anyone who is tired of a phone that dies by mid-afternoon or a laptop that has to stay plugged in. You will learn how these batteries age, which charging habits help, which settings use the most power, and which popular tips are myths.
How lithium-ion batteries age
Phones, laptops and most other portable electronics use lithium-ion batteries. Inside, lithium ions move between two electrodes as the battery charges and discharges. Each cycle causes tiny chemical and physical changes. Over time these changes reduce how much charge the battery can hold, which you notice as shorter runtime.
Research bodies such as the US National Renewable Energy Laboratory (NREL) list the main factors that affect battery life: temperature, the range of charge the battery is regularly used within, how fast it charges and discharges, and how it is stored. The battery also ages while it sits idle, so even a device in a drawer loses capacity slowly.
A charge cycle means using an amount of energy equal to 100% of the battery's capacity, not necessarily in one go. Using 50% today and 50% tomorrow adds up to one cycle. Regulators have started to set expectations here: EU rules for smartphones and tablets that apply from June 2025 require batteries to keep at least 80% of their initial capacity after 800 charge cycles. Our guide to choosing a smartphone explains how to use that kind of information when you buy.
Heat is the main enemy
Of all the factors, temperature is the easiest to manage. Apple states that the ideal ambient temperature for its devices is 16 to 22 degrees Celsius (62 to 72 degrees Fahrenheit). It adds that exposure to ambient temperatures above 35 degrees Celsius (95 degrees Fahrenheit) can permanently reduce battery capacity, and that charging in high temperatures can cause further damage. Google makes a similar point for Pixel phones: a hot battery drains much faster, even when the phone is not in use.
Cold is less harmful. Apple notes that cold temperatures reduce battery life temporarily, and performance returns to normal once the battery warms up.
Practical ways to avoid heat:
- Do not leave a phone on a car dashboard, in direct sun or under a pillow while charging.
- Remove thick cases when charging if the device feels hot.
- Avoid using demanding apps, such as navigation with the screen at full brightness, while the phone charges.
- Keep laptops on a hard, flat surface, not on blankets, so the vents can breathe.
Charging habits that help
Batteries tend to wear more when they sit at 100% charge for long periods, particularly in warm conditions. Modern devices include features that reduce this.
- Optimized or adaptive charging: Apple's Optimized Battery Charging may delay charging past 80% until shortly before you need the battery. Google's Adaptive Charging on Pixel phones learns your routine and finishes charging close to when you usually unplug. Both need a few days to learn your pattern and may not work well if your schedule changes.
- Charge limit: Some devices let you cap charging at 80%. Google offers this on Pixel 6a and later, and Apple offers a charge limit on newer iPhones. Many laptops have a similar "battery care" or "conservation mode" in their settings or manufacturer app. A limit suits you if you usually end the day with some charge left.
- Partial charging is fine: You do not need to wait until the battery is empty. Short top-ups are normal for lithium-ion batteries.
- Use a quality charger: Google advises using the adapter that came with the phone, because other chargers may charge slowly or damage the battery. A certified charger from a reputable brand is a sensible alternative.
- Fast charging: It generates more heat and puts more stress on the battery. NREL notes that fast charging can shorten battery lifespan. Use it when you are in a hurry, and slower charging overnight.
For laptops that stay plugged in at a desk most of the time, a charge limit of around 80% is usually better than holding the battery at 100% for months. If your laptop lacks that option, an occasional unplugged session helps, though the benefit is modest.
Settings that drain power
Once the battery is in decent shape, the next gains come from reducing what the device does. These are the heaviest users on most phones and laptops.
- Screen brightness and timeout: The display is usually the largest power draw. Lower the brightness, use automatic brightness, set a short screen timeout and consider dark mode on phones with OLED screens.
- Always-on display and live wallpapers: Both use power continuously. Turn them off if you do not value them.
- Background app activity: Apps that refresh in the background add up. Check your battery usage screen and restrict the few apps that use the most.
- Weak signal: A phone searching for signal uses more power. In areas with poor coverage, airplane mode with Wi-Fi turned on can save battery.
- Location services: Set most apps to "while using" instead of "always."
- Hotspot and tethering: Turn them off when you finish.
- High refresh rate: On phones with a 90 or 120 Hz screen, switching to a standard rate saves some power.
- Laptop extras: Keyboard backlight, external devices plugged into USB ports and many browser tabs with video all reduce runtime.
Myths versus facts
| Claim | What is true |
|---|---|
| You must drain the battery to zero before recharging | Not needed. Google explicitly says you do not have to run the battery from empty to full to calibrate it. Deep discharges can be harmful. |
| Leaving a phone charging overnight ruins it | Modern devices stop charging at full and many delay the final stretch. The bigger issue is heat, not the hours. |
| Closing all apps saves battery | Reopening apps from scratch often uses more power than leaving them paused in the background. |
| Any charger is fine if the plug fits | Poor-quality chargers can charge slowly or damage the battery. Use certified chargers. |
| Cold weather permanently damages batteries | Cold shortens runtime temporarily. Heat causes the lasting damage. |
| A battery needs replacing as soon as its health drops below 100% | Some loss is normal from the first months. Replacement is worth considering when the device no longer lasts your normal day or shuts down unexpectedly. |
When to replace a battery
All batteries lose capacity eventually. Check the battery health screen in your phone's settings or your laptop's battery report. If your device no longer gets through a normal day, or it shuts down unexpectedly, a replacement is usually cheaper than a new device. Use the manufacturer or a reputable repair shop, and avoid swollen batteries entirely. A battery that bulges is a safety hazard and should be handled by a professional.
Storing a device long term
If you plan to put a device away, Apple recommends charging the battery to around 50%, powering the device off and storing it somewhere cool and dry. Avoid storing it fully charged or fully empty. For storage longer than six months, Apple says to recharge it to 50% every six months. If you keep spare devices, your backup routine should cover them before you put them away.
Common mistakes
- Charging in the sun or on a hot surface. Heat damage does not reverse.
- Keeping a laptop at 100% for months. Use a charge limit if the device offers one.
- Using cheap, unbranded cables and chargers. They may charge poorly and risk damage.
- Draining the battery fully on purpose. It stresses the cells and offers no benefit.
- Ignoring battery swelling. Stop using the device and seek professional help.
- Chasing small savings. Turning off useful features rarely gives much battery back compared with brightness and heat management.
Frequently asked questions
Is it bad to charge my phone to 100%?
Occasionally charging to full is fine, and sometimes necessary. It is staying at 100% for long periods, especially in warm conditions, that adds wear. Use optimized charging or an 80% limit when you do not need a full battery.
How long should a phone battery last?
It depends on the model and how you use it. Check the maker's published figures, like the capacity retained after a stated number of cycles, and judge by whether the phone lasts your normal day.
Does wireless charging damage the battery?
It tends to produce more heat than cable charging, and heat is the main concern. If your phone gets warm on a wireless charger, remove the case or switch to a cable.
Should I keep my laptop plugged in all the time?
It is fine if the laptop manages charging properly. For best long-term health, use a battery care or charge limit setting and keep the device cool.
Next steps
- Check your phone's battery health screen and note the current capacity as a baseline.
- Turn on optimized or adaptive charging, or set an 80% limit, on your phone and laptop.
- Open your battery usage screen and restrict the two or three apps that use the most power in the background.
- Move your charging spot away from sun, heat and bedding.
