Are You Charging Your Phone Wrong? 5 Mistakes That Kill Your Battery

You're probably charging your phone wrong

You're probably charging your phone wrong, and it's costing you. The global average lifespan of a smartphone is just 2.53 years, and the battery is one of the main reasons people replace their phones.

Studies of more than 4,000 smartphone users show that most people start charging when the battery is at around 40%, with two peaks: between 6 and 8 p.m., and overnight. These are exactly the times that wear the battery down the most.

Here we reveal 5 specific mistakes and the simple fixes that can give your battery two extra years of good health. A bad battery means either an expensive battery replacement or a new phone much sooner than necessary. Either way, it can cost you hundreds of dollars.

Mistake 1: You charge overnight

Overnight charging is probably the most common charging habit, and unfortunately one of the most harmful. Your phone reaches 100% in 1 to 3 hours, but then sits at maximum voltage for another 5 to 7 hours. It's like holding an inflated balloon at its bursting point all night long.

Three factors work against your battery at the same time: extended time at maximum voltage, heat buildup, and repeated trickle-charging cycles in which the phone drops to 99% and charges back to 100% over and over again.

The fix for iPhone: Turn on “Optimized Battery Charging.” Go to Settings → Battery → Battery Health & Charging → turn on “Optimized Battery Charging.” The feature uses machine learning to hold the battery at 80% and finishes charging just before you normally unplug. Available on iOS 13 and later.

With iOS 18 (released in fall 2024), iPhone 15 and newer models got a new “Charge Limit” feature. It lets you manually set the charging limit to 80, 85, 90 or 95%. A surprising number of users don't know about this feature. You'll find it under Settings → Battery → Battery Health & Charging → Charge Limit.

The fix for Samsung: Turn on “Battery Protection” on Galaxy models from 2022 and later. Go to Settings → Battery and device care → Battery → Battery protection → choose “Maximum” (limits charging to 85%). Samsung's AI-based overnight charging algorithm keeps the battery temperature within 2 °C of room temperature during slow charging, and can extend battery life by up to 20% compared with standard fast charging.

Mistake 2: You let the battery run flat, or keep it at 100%

Lithium-ion batteries work best in the 20 to 80% charge range. This “sweet spot” significantly reduces the chemical stress on the battery cells.

A two-year study by HTX Studio, in which 40 phones were tested under controlled conditions, showed clear results: iPhones consistently kept between 30 and 80% experienced 4% less capacity loss. Android devices under the same conditions saw a 2.5% reduction in wear.

The numbers may sound modest, but over time they make a big difference. A phone charged to 80% daily will typically retain more than 90% of its original capacity after 2 years. Regularly letting the battery drop below 20% or keeping it at 100% for long periods noticeably increases wear.

Practical tip: Unplug the charger at 80% and start charging again at around 20 to 30%. It takes a bit of a habit change, but the payoff is significant.

After 3 years, an iPhone typically retains 5 to 8% more capacity than a Samsung under similar usage. Those percentage points are the difference between a battery that still lasts a full day and one that needs replacing. A battery replacement often costs $75 to $145, plus downtime.

Mistake 3: You use wireless charging every day

Wireless charging is undeniably convenient. Just set your phone down and it charges. But it comes at a price: wireless charging generates significantly more heat than wired charging, and heat is a battery's worst enemy.

Research on lithium-ion batteries shows alarming numbers. Batteries at 30 °C experience a 20% reduction in cycle life. At 40 °C, the reduction doubles to 40%. And at 45 °C, expected cycle life can be cut in half compared with operation at 20 °C. Temperatures from 25 °C to 55 °C increase the degradation rate of maximum charge capacity from 4.22% to as much as 13.24% after 260 cycles.

Recommendation: Use wired charging as your primary method to preserve the battery over the long term. Save wireless charging for quick top-ups when convenient.

And what about fast charging? Many people believe it's harmful, but HTX Studio's two-year study of 40 phones suggests otherwise: fast charging isn't as damaging as its reputation suggests. The charging range (20 to 80%) matters far more than the charging speed.

Practical advice: Remove the phone case while charging if the phone gets noticeably warm, especially when charging wirelessly. A case acts as insulation and traps the heat.

Mistake 4: You charge your phone in hot places, or under the covers

Charging your phone under the duvet, the pillow or among clothes is one of the most common mistakes. It prevents heat from dissipating and creates a little “oven” around the phone. Batteries exposed to 45 °C can degrade more than twice as fast as batteries kept at 25 °C.

Here's a fact few people know: calendar aging, meaning the chemical breakdown that happens while the phone is just sitting there, accounts for 50 to 70% of the total capacity loss most users experience over a year. Heat accelerates this process dramatically, even when you're not using the phone.

Places you should NOT charge:

• In bed under the duvet or pillow
• In direct sunlight
• In the car in summer
• On hot surfaces such as radiators or stovetops

Charge here instead: On a hard, flat surface with good airflow, in a room at normal temperature. Hot summer days, with high temperatures in cars and vacation cabins, are especially risky periods for your battery.

Mistake 5: You use a non-certified charger

Non-certified third-party chargers can deliver the wrong voltage and current, which can damage the battery, charging ports and internal circuitry on both iPhone and Samsung Galaxy. This is a widespread problem, but one that gets very little attention.

MFi certification (Made for iPhone/iPad) means Apple has tested and approved the charger for safe use with its products. USB-IF certification guarantees that the charger follows the USB standard for power and voltage. It's worth paying a little more for that peace of mind.

Cheap chargers from unknown brands on online auction sites and marketplaces are the most common culprits. In the worst case, a non-certified charger can void your phone's warranty.

BestAtTech.Com carries only certified accessories from well-known brands. We always recommend the original charger or certified alternatives, because we know it makes a real difference to your battery health.

iPhone vs. Samsung: Which handles bad charging habits better?

After 3 years, an iPhone typically retains 5 to 8% more battery capacity than a Samsung Galaxy under similar usage patterns, based on user data collected over 18 to 24 months. Apple devices also tend to last longer overall: often 4 to 10 years, while Samsung phones last 3 to 6 years on average.

Both platforms now have built-in AI tools to protect the battery. iPhone has the iOS 18 Charge Limit (a manual limit of 80 to 95%), while Samsung offers Battery Protection with an 85% limit. The problem? Most users haven't turned these features on.

The conclusion is clear: the platform matters, but your habits matter more. The 5 mistakes above apply just as much to iPhone as to Samsung Galaxy.

How to check your battery health on iPhone and Samsung right now

iPhone: Go to Settings → Battery → Battery Health & Charging. The percentage shows how much of the original capacity remains. Below 80%? Then it's time for a battery replacement.

Samsung: Go to Settings → Battery and device care → Battery status. Here you'll find similar information about the battery's condition.

Check your battery health right now, while you're reading this. Are you below 80%? Then it may be time to consider new accessories or a new phone.

Recap: Take care of your battery starting today

Here are the 5 mistakes you need to stop making:

1. Charging overnight without a charge limit turned on
2. Letting the battery run flat or keeping it at 100%
3. Using wireless charging as your primary method
4. Charging in hot places or under the covers
5. Using non-certified chargers

The single most important change you can make today? Keep your battery between 20 and 80%. This one habit can save you hundreds of dollars in battery replacements or an early phone upgrade.

BestAtTech.Com has certified chargers, cables and accessories for iPhone and Samsung Galaxy, with fast delivery from European warehouses and 14-day returns with free return shipping.

Charge smart. Save money. And if you need new gear, you know where to find it.