The phone charging mistakes that are killing your battery – and how to avoid them

Charging your phone is a mundane fixture of modern life. Most of us probably plug in our devices just after we’ve brushed our teeth at night, filling them up to 100 per cent, readying them for another day of social-media scrolling and app-based procrastination. It’s part of our routine, something we don’t really think about – until it becomes a problem, that is.

There tends to come a point in your phone’s lifespan when it starts greedily eating up its charge with an insatiable appetite. Once you could get through the working day without dropping into the red zone, battery-wise, but now you’re constantly scoping out potential charging points so you can top up on the go.

As someone who has never been fussed about gadgets, I clung on to the last phone I owned for around four and a half years. By the end, I couldn’t leave the house without a chaotic array of power banks, wires and adaptors. The most frustrating part? Woeful battery life aside, this ancient artefact was actually functioning pretty well (although, I will admit, the photos it took were rudimentary at best).

I’d like to hold on to my current phone for as long as possible, and I’m guessing that, in a cost of living crisis, you might well do, too. So is there any way that we can stop this annoying process of decline from playing out again (or at least slow it down a bit)? In order to answer that, we need to look closer at our charging routine – and ask whether we might inadvertently be hastening the demise of our own devices.

First up, a quick science refresher. Your mobile phone uses a lithium-ion battery; so does your laptop, tablet and electric toothbrush. Swapped to a rechargeable vape recently? That will run off a lithium-ion battery too. Drive an electric vehicle? There’s a high chance your car uses the same technology. Are you, for some unfathomable reason, the proud owner of a hoverboard? You can probably guess by now exactly what powers your weird device.

Lithium-ion technology emerged in the Seventies and started to become an integral part of portable tech (think handheld camcorders – remember them?) in the Nineties, thanks to their high energy density. Essentially, they can pack a large amount of energy into a small space, charge quickly and last longer than other battery types.

So how do they actually work? Essentially, a battery makes electricity from a chemical reaction; when you charge it, you use electricity to reverse that reaction. Each comprises three essential parts. There’s two electrodes: the anode (in a lithium-ion battery, this is typically made from graphite) and the cathode (made from lithium cobalt oxide). There’s also an electrolyte, a conductive medium. When your phone is being used, lithium ions move from the anode to the cathode, through the electrolyte. The process flips around when it’s on charge. “By shuttling lithium ions back and forth between the battery electrodes, the battery can store and release electrical energy,” explains Sandeep Unnikrishnan, chief technology officer at battery tech start-up Lionvolt.

But although lithium-ion technology might trounce other battery types when it comes to long life, that doesn’t mean it is infallible. Far from it. Your phone’s battery life certainly does get worse as the years go on, “due to internal electrochemical wear and tear”, Unnikrishnan says. The chemical reactions that power these batteries also cause them to slowly degrade over time – essentially, they’re on the decline from the very first time you use them (don’t think about this too deeply if you’re already prone to existential crises). Typically, they last around 500 charge cycles, or between two to three years, before their capacity takes a nosedive.

Of course, many phone contracts tend to lock customers in for two years, meaning that plenty of customers will simply ditch their old handset for an upgrade at this point. Therefore, it’s not exactly in the manufacturers’ interests to make it easy to replace your battery and keep your old device. “Once upon a time, you could easily do this replacement yourself, [but] now it’s designed to be difficult so that you can’t,” explains James Bore, director of Bores tech and security consultancy.

In 2023, however, the European Union introduced a new rule. From 2027, it will require manufacturers to ensure that customers can “easily remove and replace” batteries in smartphones, tablets and other electronics, without any specialist skills or tools. It’s a callback to those halcyon days when the chunky battery of your Nokia 3310 used to slide in and out with ease. The idea is that fewer devices will end up being chucked in landfill as a result – and the regulation will mean that phone companies will have to seriously rethink the design of any products they’re selling in the EU.

Before that, though, what can we do to eke out our battery life for as long as possible? The first thing you need to do is to stop obsessing over filling up your phone to full capacity. Many of us will feel the urge to keep it topped up to 100 per cent whenever possible. I’m certainly guilty of leaving mine plugged in when it’s long been all charged up, just in case. But although this “more is better” approach might alleviate our short term worries about our devices giving up while we’re out and about, it’s not the best for the battery in the long term.

Sandeep Unnikrishnan, chief technology officer at Lionvolt

That’s because “lithium-ion batteries experience increased stress when [they are] maintained at full charge for prolonged periods”, Unnikrishnan says. Keeping it at the 100 per cent mark just places it under extra, unnecessary strain that will hasten its downfall. Instead, “maintaining the battery charge between 20 per cent and 80 per cent is more beneficial for battery cycle life”. For this reason, Unnikrishnan recommends plugging in your phone during the day rather than overnight, as “you can monitor its charge level and unplug it before it reaches full capacity”. Think Goldilocks – not too empty, not too full, just right. Congratulations if you have the mental resilience to keep your charge on the lower end of that spectrum. The mere thought is making me anxious.

Most new phones now have built-in battery management systems to help you out. If you head to the “battery charging and health” section of your iPhone, for example, you’ll see the option to switch on “optimised battery charging”. The phone takes your daily usage and charging routine into account in order to work out when it actually needs to go above 80 per cent capacity. Android models, meanwhile, have a similar “adaptive charging” feature. Plus, many handsets have their own battery health indicator, which estimates “the phone battery’s present energy capacity”, based on “the number of cycles [it has been through], the temperature profile, [and] the voltage of charge and discharge”, Unnikrishnan says.

Temperature also plays “a crucial role”, he points out, as heat and extreme cold “can lead to electrode degradation, particularly affecting the cathode, and causing “severe” reactions at the shared boundary between the electrode and the electrolyte. For this reason, he advises against using your device while it’s charging – a habit I indulge in on a nightly basis – “as this generates excessive heat and promotes chemical degradation”. Similarly, placing your phone under a pillow or a blanket isn’t a great idea, because this will further warm it up (plus, there’s a fire risk).

And while it might be tempting to opt for one of the many super-fast chargers that are on the market, in the interests of expediency, this could be a false economy. “While fast charging offers convenience, frequent use can be detrimental,” Unnikrishnan says. In fact, you really are best off sticking with the chargers recommended by your phone’s manufacturer, even if they’re pricier than off-brand options. “Very cheap non-standard chargers should be avoided,” Unnikrishnan recommends, “as they may deliver unstable current or voltage and pose an overheating risk.”

Essentially, if you’re serious about keeping your phone battery thriving for as long as possible, you might have to ditch (or at least curtail) some of your bad tech habits. The other, glaringly obvious, option is to simply try and spend less time staring at our tiny screens, but where’s the fun in that?