Technologies
Does Charging Your Phone Overnight Damage the Battery? We Asked the Experts
Modern smartphones are protected against overcharging, but heat and use habits can still degrade your battery over time.
Plugging your phone in before you head to bed might seem like second nature. That way by the time your alarms go off in the morning, your phone has a full charge and is ready to help you conquer your day. However, over time, your battery will start to degrade. So is keeping your phone plugged in overnight doing damage to the battery?
The short answer is no. Keeping your phone plugged in all the time won’t ruin your battery. Modern smartphones are built with smart charging systems that cut off or taper power once they’re full, preventing the kind of “overcharging damage” that was common in older devices. So if you’re leaving your iPhone or Android on the charger overnight, you can relax.
That said, “won’t ruin your battery” doesn’t mean it has no effect. Batteries naturally degrade with age and use, and how you charge plays a role in how fast that happens. Keeping a phone perpetually at 100% can add extra stress on the battery, especially when paired with heat, which is the real enemy of longevity.Â
Understanding when this matters (and when it doesn’t) can help you make small changes to extend your phone’s lifespan.
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The science behind battery wear
Battery health isn’t just about how many times you charge your phone. It’s about how it manages voltage, temperature and maintenance. Lithium-ion batteries age fastest when they’re exposed to extreme levels: 0% and 100%.Â
Keeping them near full charge for long stretches puts additional voltage stress on the cathode and electrolyte. That’s why many devices use “trickle charging” or temporarily pause at 100%, topping up only when needed.
Still, the biggest threat isn’t overcharging — it’s heat. When your phone is plugged in and running demanding apps, it produces heat that accelerates chemical wear inside the battery. If you’re gaming, streaming or charging on a hot day, that extra warmth does far more harm than leaving the cable plugged in overnight.
Apple’s take
Apple’s battery guide describes lithium-ion batteries as “consumable components” that naturally lose capacity over time. To slow that decline, iPhones use Optimized Battery Charging, which learns your daily routine and pauses charging at about 80% until just before you typically unplug, reducing time spent at high voltage.
Apple also advises keeping devices between 0 to 35 degrees Celsius (32 to 95 degrees Fahrenheit) and removing certain cases while charging to improve heat dissipation. You can read more on Apple’s official battery support page.
What Samsung (and other Android makers) do
Samsung offers a similar feature called Battery Protect, found in One UI’s battery and device care settings. When enabled, it caps charging at 85%, which helps reduce stress during long charging sessions.
Other Android makers like Google, OnePlus and Xiaomi include comparable options — often called Adaptive Charging, Optimized Charging or Battery Care — that dynamically slow power delivery or limit charge based on your habits. These systems make it safe to leave your phone plugged in for extended periods without fear of overcharging.
When constant charging can hurt
Even with these safeguards, some conditions can accelerate battery wear. As mentioned before, the most common culprit is high temperature. Even for a short period of time, leaving your phone charging in direct sunlight, in a car or under a pillow can push temperatures into unsafe zones.
Heavy use while charging, like gaming or 4K video editing, can also cause temperature spikes that degrade the battery faster. And cheap, uncertified cables or adapters may deliver unstable current that stresses cells. If your battery is already several years old, it’s naturally more sensitive to this kind of strain.
How to charge smarter
You don’t need to overhaul your habits but a few tweaks can help your battery age gracefully.Â
Start by turning on your phone’s built-in optimization tools: Optimized Battery Charging on iPhones, Battery Protect on Samsung devices and Adaptive Charging on Google Pixels. These systems learn your routine and adjust charging speed so your phone isn’t sitting at 100% all night.
Keep your phone cool while charging. According to Apple, phone batteries perform best between 62 and 72 degrees Fahrenheit (16 to 22 degrees Celsius). If your phone feels hot, remove its case or move it to a better-ventilated or shaded spot. Avoid tossing it under a pillow or too close to other electronics, like your laptop, and skip wireless chargers that trap heat overnight.
Use quality chargers and cables from your phone’s manufacturer or trusted brands. Those cheap “fast-charge” kits you find online often deliver inconsistent current, which can cause long-term issues.
Finally, don’t obsess over topping off. It’s perfectly fine to plug in your phone during the day for short bursts. Lithium-ion batteries actually prefer frequent, shallow charges rather than deep, full cycles. You don’t need to keep it between 20% and 80% all the time, but just avoid extremes when possible.
The bottom line
Keeping your phone plugged in overnight or on your desk all day won’t destroy its battery. That’s a leftover myth from a different era of tech. Modern phones are smart enough to protect themselves, and features like Optimized Battery Charging or Battery Protect do most of the heavy lifting for you.
Still, no battery lasts forever. The best way to slow the inevitable is to manage heat, use quality chargers and let your phone’s software do its job. Think of it less as “babying” your battery and more as charging with intention. A few mindful habits today can keep your phone running strong for years.
Technologies
25 years after 9/11, the U.S. starts rolling back travel restrictions, from liquids to gate access
Years after 9/11, the U.S. government is walking back some security screenings as threats and technology evolve.
The Sept. 11, 2001, terror attacks reshaped how we travel, from how we pack our toiletries to what we wear when we fly. Airport checkpoints for almost a quarter century for most travelers have meant shoes off. Limitations on liquids. And no tearful, cinematic gateside farewells or joyful welcomes.
But 25 years later, the U.S. government is starting to ease some of the restrictions, which include measures that were tied to other attacks attempted in the months after 9/11.
Last year, the Department of Homeland Security, which was formed after the attacks, said flyers can leave their shoes on at airports, a major change for travelers going through regular security.
That rule was introduced after Richard Reid, who became known as the “shoe bomber,” tried and failed to ignite explosive material in his shoe on a Paris-to-Miami flight in December 2001.
Rules for liquids are officially unchanged. Those regulations for liquids in carry-ons stem from 2006, when British officials foiled a plot to bring liquid explosives on flights.
New scanners installed at some airport checkpoints allow travelers to leave liquids in their bags before going through screening, though availability varies by airport and checkpoint. Limits on liquid container size remain in effect.
“The technologies today are better than they were a long time ago and some of the technology that’s been deployed is better than it was five years ago,” said Jeff Price, a professor at the Metropolitan State University of Denver’s Department of Aviation and Aerospace Science and an airport management consultant.
Another change since that era is the number of options customers have for airport screening. The Transportation Security Administration, for $76.75 covering five years, offers PreCheck, in which travelers undergo prescreening services and can use expedited screening lanes.
“If you’ve got a few bucks, yeah, you can reduce the amount of screening and jump the line,” Price said. “The other side of that is when you do become a member of PreCheck, you give up a lot more of your personal data to the government, and that’s the trade-off.”
There’s also a private option with Clear, with a shorter identification check line, in exchange for prescreened biometric data.
Gate greetings return
The new changes are going beyond security.
TSA this week launched a free program allowing eligible trusted travelers, including TSA PreCheck members, to apply for access to secure gate areas without a boarding pass.
The program is called “Gateside,” and the agency has rolled it out at 13 U.S. airports, including Dallas Fort Worth International Airport, Los Angeles International Airport, Detroit Metropolitan Wayne County Airport and Salt Lake City International Airport.
The area beyond TSA screening has been heavily restricted since 9/11. In launching the program, the agency said PreCheck members who use the program can “meet family members at their gate, join a friend on a long layover for lunch or dinner, visit airport dining and shopping locations, or greet service members returning from deployment.”
Participants must apply online one to three days in advance and receive approval before entering through security.
Privatization attempt
Some of the tweaks to security have been more rocky.
The TSA late last month scrapped a program it called TSA Gold+ that would provide privatized security at certain airports.
The new head of TSA, David Cummins, who took the top role in early August, said that a new screening partnership program will “replace TSA Gold+ to better harness the role of the private sector in delivering a safer, more secure, and more efficient aviation system.”
TSA didn’t respond to requests for further comment.
Tampa International Airport in Florida had reviewed the program starting in May, in part because it could shield the airport from the impact of government shutdowns, airport Chief Operating Officer John Tiliacos told reporters last month. Those shutdowns left TSA officers without regular paychecks for months, and staffing shortages led to long lines at airports around the country. The chance to add new technology was also a draw.
Tampa decided not to move forward with the program, and TSA announced its replacement shortly after. Tampa’s Tiliacos told reporters last month “we weren’t quite satisfied that we were getting all of the answers to our questions regarding the technology” and that drove the airport’s decision to opt out.
Evolving threats
While some rules travelers have lived with for decades might be fading, the aviation sector is still dealing with changing threats.
“You have AI. You’ve got cybersecurity issues that continue to pop up. Drones are a major issue,” said Keith Jeffries, vice president of aviation security company K2 Security Screening Group, who is retired from the TSA and was the agency’s security director at Los Angeles International Airport. “It’s the role of security and protecting, especially the transportation sector, it’s getting broader, and other technologies are trying to keep up.”
As security technology evolves, so does the energy of potential attackers to overcome whatever obstacle they have and send their message.
Deterrents are important, but Jeffries said: “There is no such thing as the perfect security mousetrap. It doesn’t exist.”
Technologies
Houthis reportedly advance to key Red Sea island, further threatening crucial oil choke point
The advance raises the threat to shipping near the Bab el-Mandeb Strait, a waterway that connects the Red Sea to the Gulf of Aden to global markets.
The Iran-backed Houthis reportedly advanced to Yemen’s strategic Perim Island on Friday, delivering a major boost to the militant group’s push to take control of one of the world’s most important shipping choke points.
The capture of Perim Island, which was reported by several news agencies, citing multiple Yemeni government sources, comes just one day after the Houthis seized Yemen’s port city of Mokha on the Red Sea coast. CNBC could not independently confirm the report.
The rapid ground offensive is seen as a severe setback to Saudi Arabia and the Yemeni forces it backs and puts Iran and its proxies on course to exercise control over two critically important oil choke points on either side of the Arabian Peninsula: the Bab el-Mandeb Strait and the Strait of Hormuz.
Perim Island is a small and rocky area of land that divides the Bab el-Mandeb Strait, a waterway that connects the Red Sea to the Gulf of Aden and to global markets.
There are concerns that the Houthis’ advance toward the Bab el-Mandeb Strait could have significant ramifications for global trade, particularly if the militant group ratchets up threats or attacks on Red Sea shipping.
The Houthi advance prompted Saudi Crown Prince Mohammed bin Salman to personally press President Donald Trump for U.S. military intervention, MS NOW reported later Friday, according to a person familiar with the conversations.
The crown prince spoke with Trump twice Thursday and urged him to strike the Iranian-backed group as it closed in on the Bab el-Mandeb. Trump declined, saying the U.S. does not plan to widen its regional military campaign to include the Houthis, according to the person, who was granted anonymity because of the sensitive nature of the conversations. Axios first reported the calls.
A senior administration official told CNBC the U.S. remains focused on protecting core national security interests, including freedom of navigation in the Red Sea, “while empowering our regional partners to take the lead in managing and resolving regional security challenges.”
The official added that the U.S. is “in continuous dialogue with Saudi Arabia.”
The capture of Mokha marked a “major blow” to Saudi Arabia as it raises the possibility of the group exerting a tighter grip on the Bab el-Mandeb Strait, according to Hamish Kinnear, principal Middle East and North Africa analyst at risk intelligence company Verisk Maplecroft.
Mokha is situated about 75 kilometers (46 miles) north of the Bab el-Mandeb Strait.
“The Houthis were already threatening Saudi shipping from previous positions, but their capture of Mocha opens up the possibility of further advances towards the Bab el-Mandeb coastline and a tighter grip on the chokepoint,” Kinnear said in a research note.
As the war continues, Kinnear said both Tehran and Washington believe time is on their side, making a new truce unlikely for now.
“Oil and gas prices, and more specifically refined products such as diesel, will continue to tick upwards while that remains the case – even if US convoys and Strait of Hormuz export alternatives cushion the price impact,” Kinnear said.
The strategic importance of the Bab el-Mandeb Strait has grown significantly since the start of the U.S. and Israel’s war against Iran in late February, with the waterway emerging as an alternative route for crude moving toward Asia.
What next for oil prices?
Oil prices traded sharply lower on Friday, but both major benchmarks could still end the week above $100 per barrel for the first time since mid-May.
International benchmark Brent crude
The resilience of the oil market is being tested by a clearer recognition of the mounting threat to regional supply, strategists at ING said, with energy market participants seen repricing both the duration and severity of the conflict.
Even as flows continue through the Strait of Hormuz, ING’s strategists said flows remain well below prewar levels, underlining how fragile the situation has become.
“Saudi energy infrastructure and crude oil exports from the Red Sea are increasingly at risk, with the Houthis in Yemen targeting Saudi Arabia,” ING’s Warren Patterson and Ewa Manthey said in a research note published Friday.
“As the Houthis have taken control of the Red Sea port of Mokha in Yemen, recent events increase the threat to shipping around the Bab al-Mandeb Strait,” they added.
— Luke Fountain contributed to this report.
Technologies
Wall Street analyst warns AI stock rally is approaching its peak. Here’s the analysis
Capital Economics warns that the AI stock market boom is approaching its end, with earnings growth expectations at dot-com bubble peak levels and foreign ownership of US stocks at record highs.
A variety of equity market bubble indicators suggest that while the S&P 500’s upward trajectory may continue this year, its medium-term outlook appears weak given the market’s current frothiness, according to Capital Economics. “Most indicators suggest the AI equity boom is nearing its conclusion,” Capital Economics’ senior market economist James Reilly stated Thursday in a note. Capital has maintained a more optimistic stance than most on the stock market since mid-2023, reflecting the belief that AI would be a transformative technology. Its year-end-2026 S&P 500 forecast has consistently exceeded consensus expectations. However, the firm has also maintained that the AI-driven rally constitutes a bubble that will eventually collapse. To identify and assess a late-stage market bubble, Reilly examines eight indicators, including valuations, earnings, index concentration, equity issuance, and foreign interest in U.S. equities. Some of these metrics are already at or near levels that preceded previous stock market peaks. The analysis reveals that while market variables like earnings expectations align with a market peak, others such as volatility and leverage appear slightly less alarming. Earnings stand out as the most significant warning sign. Expectations for S&P 500 earnings growth are at levels last seen during the dot-com bubble peak, while long-term EPS growth forecasts have surged to record highs. According to Reilly, the heavy concentration of this expected growth in the technology sector means that any signs of weakness in tech companies’ earnings will significantly impact the index. Other indicators are also flashing warning signs. Index concentration is at dot-com-era extremes, net equity issuance has turned positive, and foreign ownership of U.S. stocks is at a record high. Reilly noted that another wave of IPOs and share sales could be particularly significant, as similar issuance booms have historically coincided with market peaks. “Based on past performance, this suggests that the end of the bubble is just months away, rather than years,” he said. Measures of leverage are not yet alarming compared to other factors, though the analyst warns they are moving in a “concerning direction.” While volatility metrics appear consistent with a mid-stage bubble, Reilly notes that constituent-level volatility is not as extreme as it was near the end of the dot-com boom. “While we continue to believe that the S&P 500 will rally from around 7,650 now to 8,250 by end-2026, we ultimately forecast it to fall back to 6,500 by end-2027,” he wrote. These projections would equate to an 8% gain this year and a 21% decline in 2027.
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