Is Overnight Charging Bad For Our Phones?

Many of us have a habit of using our phones all day and charging them all night. Many of us also have the habit of worrying about overcharging our phones if we leave them on charge all night. But is this worry justified? Well, it is complicated. Believe it or not, this is a topic of real contention among tech experts and there are multiple schools of thought surrounding this topic. But before we dive into this topic, it may be pertinent to understand how the batteries in our phones work.

So, most modern smartphones have what is called a Lithium-ion battery. This battery is made up of multiple components including, but not limited to, anode, cathode and electrolyte. According to the United States of America’s Department of Energy, the anode and cathode store the lithium and the electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa. 

The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector. The electrical current then flows from the current collector through a device being powered (in this case, our phone) to the negative current collector.

The Energy Department states on its website energy.gov that during discharging, the lithium ions in the battery travel from the anode to the cathode and when charged, they flow from the cathode to the anode.

So then, is overcharging something we should worry about? Well, in the strictest sense, no modern smartphones are designed to stop charging when the battery reaches 100 per cent, even if it is plugged in. It does not mean you can put your phone on charge and forget about it, it just means that it has safeguards in place.

But, as mentioned above, this issue is complicated. While overcharging, in and of itself, does not damage or degrade your phone battery, heat does. And charging generates heat.

We may have noticed that our phone heats up when it is connected to the electrical socket. And the longer it is connected, that is, on charge, the hotter it gets. When charging overnight, we leave our phones plugged in for six to eight hours straight. At night, we also have our doors and windows closed or only partially open, meaning there is little ventilation. Some of us also put our phones on the bed near us or under pillows and cushions which are very insulating by nature. These practices make the phone hot and damage not only the battery but other parts as well.

So, those of us who prefer to charge our phones while we sleep can breathe a sigh of relief. ‘Overcharging’ will not damage our batteries as long as we prevent overheating and ensure ventilation. In fact, according to Selby, one of Australia's largest online retailers of Home Theatre and HiFi accessories, it is over-discharging that we actually have to worry about. Regularly allowing our phones to reach zero per cent and die can irreversibly harm our batteries. So, it is a good idea to charge our phones before they reach 15 or 20 per cent or whatever levels are recommended by the manufacturers. 

Similarly, as far as possible, we should only use the charger that came with our phones. If we have to get a new charger, we must choose one that is manufacturer-recommended and/or certified. 

Chargers do not look like much but they have special hardware that need to be compatible with our phones to ensure a safe charge. Bad or incompatible chargers can cause a host of problems.

So, to sum up, what are the dos and don’ts for charging your phone? Well, first off, do not leave your device plugged in for extended periods. 

As we have established, overcharging is not an issue but overheating is. On this note, also keep your phone out of direct sunlight and do not keep it in insulating conditions such as your pocket, bag or under your pillow for too long. Heat is always bad for your phone. 

Furthermore, to avoid frequent charging, use battery-saving modes to extend battery life. Smartphones almost always have settings that help preserve charge by reducing screen brightness, disabling background apps, curtailing certain functions, etc.

But the unfortunate fact is, batteries degrade over time, no matter what we do. If we are lucky and take really good care of our phones, our batteries might work for five years. Otherwise, we will have to get our batteries changed every two or three years.