For many of us in our 50s, 60s, and beyond, our smartphones have become indispensable lifelines. They connect us with grandchildren, old friends, and the wider world. We use them to check the weather, read the news, play a quick game of Sudoku, or video chat with family across the country. It’s a modern miracle we’ve warmly welcomed into our lives.
And because we’re constantly using them, they’re constantly running out of battery. So, what’s the natural solution? We plug them in. And then, because we’re busy or don’t want to be interrupted, we keep right on using them. We scroll through Facebook, answer emails, or continue a conversation while the little lightning bolt icon glows in the corner.
It feels efficient. Multitasking. What could possibly be wrong with this picture?
Plenty, as it turns out. This common habit, which seems as harmless as talking on a corded phone from the kitchen wall, is—according to electrical engineers and safety experts—a potentially dangerous gamble. That convenient device in your hand can, under the right (or wrong) conditions, transform from a lifeline into a serious hazard.
I learned this not through a scary news story, but through my own brother, Carl. Carl, 62, is a retired school teacher and a dedicated gadget lover. He’s always on his phone, reading history blogs or watching documentaries. One evening, he was lying in bed, his phone plugged into the charger on his nightstand, engrossed in a video about the Roman Empire.
He first noticed the smell. A sharp, acrid, plasticky odor that he couldn’t place. Then, he felt the heat. It wasn’t just the normal warmth of a working device; the back of his phone and the charging cable were becoming uncomfortably, alarmingly hot to the touch. He unplugged it in a panic, his heart racing. The phone continued to radiate heat for several minutes afterwards.
Shaken, he called me the next day. I, in turn, called a friend of mine, David, who is an electrical engineer. What David explained over the phone was so eye-opening that I invited him to explain it to a group of our friends at our weekly coffee meetup. What he shared had everyone putting their phones down and paying very close attention.
“You have to understand,” David began, “that your phone is not a simple appliance like a toaster. It’s a sophisticated, miniaturized computer with a powerful battery. And charging it is a complex chemical and electrical process. Using it while it’s charging disrupts this process in ways that can lead to three major risks.”
Risk 1: The Thermal Runaway – A Chain Reaction You Can’t Stop
“This is the big one,” David said, holding up his phone. “When you charge your phone, the battery generates heat as a byproduct of the energy transfer. That’s normal. The phone’s hardware and software are designed to manage this heat and regulate the charging speed to keep it safe.”
“But when you’re simultaneously using the phone,” he continued, “you’re adding a significant second source of heat. The processor, the screen, the radio antennas—they all generate their own heat when working hard. You’re essentially trapping that heat inside the device. The phone can’t dissipate it fast enough.”
He used an analogy that resonated with all of us. “It’s like running your car’s engine at full speed while also trying to force-fill the gas tank at the pump. The system becomes overwhelmed.”
This excessive heat stresses the lithium-ion battery’s internal components. It can cause the flammable electrolyte liquid inside the battery cells to break down and generate more heat. This can start a catastrophic positive feedback loop called “thermal runaway.” The heat creates more heat, which creates even more heat, until the battery ignites or explodes.
“This isn’t science fiction,” David stressed. “It’s a known chemical process. And while modern phones have safety circuits to prevent this, they are not foolproof. Overheating from simultaneous use and charging is one of the primary ways those safety measures can be overwhelmed.”
Risk 2: The Slow Death of Your Battery (And Your Wallet)
Even if you avoid a dramatic event, you are slowly killing your phone’s battery. Heat is the number one enemy of lithium-ion batteries. Consistent exposure to high heat during charging significantly accelerates the degradation of the battery’s components.
“That ‘maximum capacity’ percentage in your phone’s settings?” David asked. “It drops much, much faster if you constantly overheat the battery. You’ll find your phone won’t hold a charge like it used to. You’ll be plugging it in more often, which creates more heat, which degrades it further—a vicious cycle.”
Within a year, you could be looking at a battery that barely lasts half a day, necessitating an expensive battery replacement or, worse, pushing you to buy a new phone prematurely. For those on a fixed income, this is an unnecessary financial hit.
Risk 3: The Voltage Spike and the “Dirty” Grid
David then touched on a factor most of us never consider: the quality of the power coming from our wall outlets.
“The power from your wall is alternating current (AC). Your phone needs direct current (DC). That little charging brick is a converter,” he explained. “But not all converters are created equal. Cheap, off-brand, or damaged chargers and cables can do a poor job of this conversion, leading to inconsistent or ‘dirty’ power flow with minor voltage spikes.”
When the phone is idle and charging, its internal circuits can usually smooth out these minor inconsistencies. But when the phone is under a heavy processing load from being used, these small voltage spikes can become more damaging to the phone’s sensitive internal components, particularly the battery management system, increasing the risk of failure.
The Safe Charging Protocol: What to Do Instead
So, what’s the solution? David offered a simple, easy-to-follow protocol for safe charging:
- Charge First, Use Later: Treat charging as a dedicated activity. Plug your phone in and walk away. Let it charge to your desired level (ideally between 80-90% for battery longevity) before using it again.
- Invest in Quality: Use only manufacturer-certified (MFi for Apple) or reputable brand chargers and cables. That cheap gas station cable is not worth the risk.
- Charge on a Hard Surface: Never charge your phone on a bed, sofa, or under a pillow. These soft surfaces trap heat. Always place it on a hard, flat, well-ventilated surface like a nightstand or desk.
- Unplug at 100%: Don’t leave your phone plugged in overnight. Modern phones charge quickly. A full charge takes 1-2 hours, not 8.
- Listen to Your Phone: If your phone or charger feels excessively hot to the touch, unplug it immediately and let it cool down. That’s a clear warning sign.
The room was silent after David finished. Carl’s story was no longer an isolated incident; it was a cautionary tale for all of us. We had all done it a hundred times without a second thought.
The takeaway was clear: that simple, multitasking habit is a hidden risk. We would never leave a pot boiling on the stove unattended or overload an electrical outlet. Yet, we were tempting fate with a device containing a powerful energy-dense battery mere inches from our faces.
The convenience of scrolling through photos while plugged in is not worth the risk of a fire, a ruined device, or personal injury. My brother was lucky. He smelled the warning and acted. Not everyone gets that warning.
Now, when I plug my phone in, I put it down. I use that time as a forced break—to read a physical book, talk to my wife, or just enjoy a moment of quiet. It’s a small change in habit that pays a huge dividend in safety and peace of mind. In our golden years, that’s a charge worth preserving.