Apple, Samsung and Google reveal what’s secretly killing your phone battery

For years, smartphone owners were told not to leave their devices plugged in too long or their battery would suffer. But today, Apple, Samsung and Google say that fear belongs to the past. Thanks to smarter charging systems built into modern phones, plugging in overnight or all day is no longer harmful like it once was.

Instead, the major concern has shifted to something else entirely: heat.

Why modern batteries don’t “overcharge”

Lithium-ion batteries are designed to stop receiving full power once they reach 100%. Smartphones now pause or slow charging once that point is reached, topping up only when needed. This prevents the stress that caused damage in older devices.

Still, battery health naturally declines over time. The faster a battery wears down depends largely on temperature, charging behaviour and overall usage. And heat is considered the biggest damaging factor.

What Apple says

Apple calls phone batteries “consumable components” that lose capacity gradually. To delay that process, iPhones use Optimised Battery Charging, a feature that learns when the user normally wakes up. The device remains near 80% for most of the night and completes charging just before morning, reducing time spent at high voltage.

Apple also recommends:

Keeping the phone between 0°C and 35°C (32°F to 95°F)

Avoiding cases that trap heat while charging

Moving a device to a cooler spot if it becomes warm

What Samsung says

Samsung tackles charging stress by giving users more control. Battery Protect, available under Battery and Device Care settings, caps the maximum charge level at 85%. This feature is particularly useful for users who keep their phones plugged in at desks or overnight, cutting down on voltage load and heat exposure.

Samsung also recommends:

Avoiding tight spaces during charging, like under pillows or inside cluttered backpacks, because insufficient ventilation can quickly push temperatures into the danger zone.

Like Apple, Samsung recommends certified charging accessories that deliver stable current, preventing heat spikes caused by low-quality components.

What Google says

Google focuses on timing rather than voltage caps. Pixel phones feature Adaptive Charging, which tracks user alarms and typical wake-up times. When enabled, the phone slows the final 20% of charging, making sure it doesn’t sit fully charged for hours on end.

Pixels also incorporate adaptive thermal management, which means if heat climbs while the phone is plugged in, charging speed drops automatically to preserve battery health. Google further adds Adaptive Battery and App Standby tools that limit power-hungry apps in the background, reducing heat generation throughout the day.

Other major Android brands including OnePlus, Oppo, Xiaomi and Sony, now offer their own variations of smart charging, learning user habits or limiting maximum charge to better preserve long-term health.

Leaving your phone plugged in isn’t the threat it used to be. The major tech giants have built automated protection systems to keep batteries healthy. Still, simple habits like avoiding charging in hot places and using trusted accessories can help your phone last longer.