If your iPhone is getting low on juice toward the end of the night, but you want to have it charged up by morning, you might be tempted to plug it in all night, but is keeping your iPhone charging overnight bad for the battery?
There are a lot of ways to fix bad iPhone battery life and get better battery life overall out of your iPhone, but there are a lot of things that you might not be doing that could get you better battery life in the long run.
However, one thing that users have argued about in the past, or may have just been curious about, is whether or not leaving your iPhone charging overnight is bad for the device’s battery.
Years ago, before battery technology vastly improved to what it is now, leaving your battery-powered devices plugged in all night long was bad for the battery and could seriously harm the health of the battery long-term, simply because the battery would “overcharge” and receive more and more juice, even though the carton was already full.
However, battery technology has advanced quite a bit since then, and lithium-ion batteries (which are found in iPhones) are unable to overcharge. Older battery technologies, like nickel-cadmium (Ni-Cd) and nickel metal hydride (Ni-MH) batteries are prone to overcharging, and there are still some devices today that uses these types of batteries, like rechargeable alkaline batteries and some power tool batteries. However, your iPhone uses the newer lithium-ion battery technology.
Popular Mechanics says that lithium-ion batteries don’t overcharge, and instead will “trickle charge.” This happens when the battery reaches 100% and the charger vastly slows down the voltage that it sends to your iPhone, just enough to keep it charged up without overcharging.
More specifically what happens is that the whole time you have your iPhone plugged in and it’s at 100%, it’s really going from 100% to 99% or even 98% and then back up to 100% many times over until you finally unplug it, hence the name “trickle charging.”
However, this can cause ever-so-slight degradation of the battery over time. This is because batteries have a lifespan measured in cycles. One cycle equals a full battery discharge from 100% to 0%. So technically, trickle charging counts toward your battery’s cycles. It’s not said how long you’d have to leave your iPhone plugged in for trickle charging to have a massive effect on cycle count, but it can at least have some sort of effect.
Your iPhone’s battery has a lifespan of several hundreds of cycles, so you likely don’t need to worry about it at all, but those numbers can add up quickly if you recharge every day. Still, though, most users upgrade their smartphones every two years anyway, and a battery can easily last that long without much degradation, if any.
Plus, Popular Mechanics says that “leaving your phone on the charger all night (or all day) is far better for your battery than running it down and charging it up.”