I always get asked about when to and how often I charge my iPhone.
Basically my iPhone is always connected to the charger during the following circumstances:
- When I'm finished teaching or using it
- When I'm in the car
- At night while I am sleeping
There is a myth that you should let the battery run all the way down before charging it. But the iPhone doesn't like to be below 20%. The battery indicator light will turn red at 19%.
The phone won't update or backup with below 20% charge.
Typical smartphone batteries are designed to last around a year and a half, or about 400 full cycles before their capacity begins gradually eroding; so fears about charging a battery after it’s fully charged are largely overblown.
Having your phone plugged in at night doesn’t diminish the battery. It’s all about cycle count — it’s all about how you actually use the battery, how much work you’re making the battery do.
In terms of ‘cycle counts’ in relation to battery performance and long-term decay, it’s not about how many times a day you plug-in and unplug your device from a power source, but rather the number of times it reaches full capacity. For example, charging your iPhone with 10% battery up to 60% would constitute a ‘half-cycle’ — or 50% of a full, 0-100% charge.
“In terms of the gradual erosion of battery life, what must be understood is that phone batteries are constantly in a state of decay,” "Sleeping with a phone charging overnight will make no noticeable difference in the process.”
Tips for Overnight Charging
Thanks to modern advancements in battery technology, most smartphones are designed to significantly reduce their draw current once their batteries have reached 100% capacity. This is worth noting for two reasons: one, if you’re like most people, you charge your smartphone while you’re asleep, and two, because you’re likely not going to wake up in the middle of the night just to unplug it once it’s reached full capacity.
What’s definitely worth worrying about is the temperature of your device and where you place it. Since battery charging is a heat-inductive mechanism, your smartphone will heat up substantially while it’s plugged in. And therefore, while it may be convenient or perhaps even comforting to sleep with your smartphone beside you, it’s worthwhile to ensure you’re not smothering it with your pillow or blanket.