In “We debunk myths about smartphones.”, we provide useful information, practical explanations, and the main points to consider when working with smartphones and electronics.
Some phone advice gets passed around for years without anyone checking it again: close every app, never charge overnight, a "waterproof" phone can go swimming. A few of these tips made sense back in the days of old batteries and early smartphones. Others were wrong from the start.
This article first appeared in September 2023. We rewrote it in October 2026 and checked every claim against Apple, Google and Samsung documentation, health authorities and published research. Repair myths (losing data at the repair shop, turnaround times, swapping a battery at home) are covered separately in our article on five phone repair myths. Here we stick to everyday phone use.
A phone gives off radiofrequency energy, which is non-ionizing radiation. It does not carry enough energy to break chemical bonds in DNA the way X-rays or nuclear radiation can. The US Food and Drug Administration (FDA) states that the weight of scientific evidence has not linked radiofrequency radiation from cell phones with any health problems.
So where does the worry come from? In May 2011 the International Agency for Research on Cancer (IARC, part of the WHO) classified radiofrequency electromagnetic fields as "possibly carcinogenic to humans" (Group 2B). That rating rested on limited evidence from observational studies. In September 2024 a WHO-commissioned systematic review led by the Australian agency ARPANSA was published: the authors started from more than 5,000 studies published between 1994 and 2022, included 63 in the final analysis and found no association between mobile phone use and cancers of the head.
There is one real precaution, of a different kind. The FDA advises people with an implanted pacemaker or defibrillator to keep phones and smartwatches at least six inches (about 15 cm) away from the device, because of the magnets inside and possible interference. Do not carry the phone in a chest pocket if you have such an implant, and follow your doctor's instructions.
A phone does not keep pushing current into the battery forever. The charging controller stops or reduces the current as the battery nears full. What wears a lithium-ion battery over time is mainly heat and the hours it spends at 100%, and manufacturers have added features to deal with exactly that:
Overnight charging is fine, then, as long as the phone does not get hot. Apple recommends avoiding ambient temperatures above 35 °C and taking the device out of certain cases if it gets hot while charging. Do not leave a charging phone under a pillow, on the bed or in direct sun. If you are also wondering about high-power chargers, we have a separate article on whether fast charging affects battery life.
This advice comes from old nickel-based batteries, which had a "memory effect". The lithium-ion batteries in today's phones do not have that problem. Apple says plainly that you can charge them whenever you want and that there is no need to let them discharge 100% first. Wear is counted in charge cycles: one cycle means using an amount equal to 100% of the capacity, possibly spread over several days, for example 75% one day and 25% the next.
Running the battery flat again and again does not "train" it. Over time it puts more strain on it. If you need to store an unused phone for a few months, Apple recommends leaving it about half charged in a cool place. When a battery has clearly lost capacity, our guide on when a phone battery should be replaced covers the signs to look for.
Apple and Google both say otherwise. In the iPhone User Guide, Apple writes that quitting apps you are not using does not prolong battery life. Google's Android help states that even if you do not close apps, you will not run out of memory or battery, because Android manages them automatically.
The reason is simple. Apps in the recent apps list are normally suspended by the system and do not use the processor. When you force-close one and open it again, the phone has to load it from scratch, which takes more energy than switching back to it. Close an app only when it freezes or misbehaves. If your battery drains fast, look at battery usage by app in Settings: that shows which apps really consume power, including in the background.
The megapixel count only tells you how many points make up the image. Quality also depends on the size of the sensor and of each pixel, the lens, stabilization and software processing. An official example: when Apple launched the iPhone 14 Pro in 2022, it explained that the 48MP main sensor combines every four pixels into one larger quad pixel for most photos and keeps the image at 12MP. The stated aim was better capture in low light. Full 48MP resolution remained available in ProRAW for anyone who wants more detail when editing.
In practice, compare real photos taken in the same conditions, especially in the evening and indoors, rather than the number on the box. A scratched lens or a cracked camera cover glass will spoil a picture far more than any difference in megapixels.
An IP rating describes a laboratory test. It is no guarantee for every situation. For recent iPhones, Apple lists IP68 under IEC standard 60529 with a maximum depth of up to 6 meters for up to 30 minutes; older models have lower limits. On the same page, Apple asks you to avoid swimming or bathing with the phone, pressurized water, saunas and intentional submersion.
Two points matter most. First, Apple says splash, water and dust resistance are not permanent conditions and may decrease as a result of normal wear; drops and disassembly can affect it too. Second, Apple states that liquid damage is not covered under its warranty, although you may have rights under consumer law.
After a screen or back cover replacement, the seal depends on the gasket and the adhesive applied at the repair shop. Some shops check it with a tightness tester, but even a passed test is no guarantee against water.
RELIFE RL-086 mobile phone tightness testerout of stock
If the phone does end up in water, do not put it in rice and do not heat it with a hair dryer: Apple warns that small particles of rice can get inside the device. The right steps are described in the repair myths article linked above.
The last point often applies to charging. A phone that charges slowly or keeps dropping the connection frequently has a faulty cable or a weak charger, not a battery "ruined by overnight charging". A USB tester placed between the charger and the phone shows the voltage and current that actually reach the device.
Mechanic Power-Diy USB tester (30V / 5A)out of stock
| Myth | What the sources say |
|---|---|
| Phone radiation causes cancer | The FDA and the WHO-commissioned review (2024) found no link; people with cardiac implants keep phones six inches (15 cm) from the device |
| Overnight charging ruins the battery | The charging controller and optimized charging features limit time at 100%; heat is the real problem |
| Drain the battery to zero | Lithium-ion batteries have no memory effect; charge them whenever you like |
| Closing apps saves battery | Apple and Google say it does not help; the system manages memory itself |
| More megapixels, better photos | Sensor, pixel size, lens and processing matter |
| IP68 means waterproof | A lab test under controlled conditions; protection decreases over time, and liquid damage is not covered by Apple's warranty |
The GSM Forsage catalogue has displays, batteries, tools and components for mobile electronics repair. Contact us about availability and wholesale prices.
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