When I found an iPhone 6 ($ 197 on eBay) on eBay for only £ 75 ($ 95, $ 145), I was extremely pleased. But I was less pleased when I found out that the battery had aged to the point where the software boosted its performance. But instead of sending the phone away and getting the buyer's remorse, I decided to buy a replacement battery and tools from iFixit to replace the battery myself.
After an hour of work, I replaced the battery and the iPhone 6 ran perfectly again. I'm not giving step-by-step instructions here – go to iFixit and get a kit if that's what you're looking for – but I want to give my experience, including how easy it was to do, and hopefully answer some of the questions you can have if you also need a new battery.
Note that all maintenance you do on your own devices is done entirely at your own risk.
Why do you need to replace a phone battery?  Batteries are aging over time and considering that the iPhone 6 was released six years ago, it was no surprise that the one I bought did not run in good condition. Once, the phone unexpectedly restarted when in use, and it flashed a warning dialog that read: "This iPhone has experienced an unexpected shutdown because the battery could not deliver the required peak power. Performance management has been used to prevent this from happening again." the phone itself knew it had a battery.
In short, the phone's performance can be severed if it no longer meets the power requirements. It is possible to turn off the throttle, but this will result in more frequent crashes. Neither situation is ideal, so a battery change seemed a smart way forward for me.
How much does a replacement iPhone battery cost?
The problem with my situation was especially that I bought the phone for so little at first that spending more money on a battery replacement service denied some of these initial savings. Apple's official replacement service costs £ 49 ($ 49), which is more than half the price of my iPhone 6 that I bought. Being in the middle of the coronavirus lockout also meant it was not an option to get to an Apple store, and sending it by mail would bring the total cost to £ 56.44.
However, iFixit sells a DIY compensation package for £ 35 (including postage to my home in Scotland). It costs $ 30 in the US and with shipping costs of $ 37.96. It's not a huge saving compared to Apple's official replacement, but every little bit helps.
What's in the kit?
iFixit's kit comes with a third-party replacement battery that does not from Apple, since Apple does not sell its parts separately. It also has all the tools needed to open the phone and remove the old battery. The only thing I needed was a hairdryer to heat up and remove the glue.
Have you replaced a battery with your warranty?
If you open an iPhone, the warranty will expire, but if your battery ages so it must be replaced, it is likely that you have already expired the 12-month warranty period.
Is it safe to replace a battery yourself?
This is not so easy to answer. The iFixit guide gives very detailed instructions on the steps involved, but there were a few points that made me nervous. One step was to heat the back of the phone with a hair dryer to loosen the glue that holds the old battery in place.
In particular, it noted that the heat was "slightly too warm to touch comfortably", which I found a bit vague. Especially since that section also warned that "iPhone overheating may light the battery." But how hot is it too hot? What signs would I see if it is overheating? I couldn't find this information, and as such, I wasn't too sure how close to overheating I may have been.
Shortly after, while trying to burn out the old battery, I accidentally tore into what looked like the black one wrapping around that battery. I was pretty sure that the battery itself was not punctured – there was no smoke or hiss – but I would have felt much more comfortable if I had "emergency" at hand about what I would do if the battery ignited.
Is it easy to replace a battery yourself?
Up to a point, yes, and I'm normally not "practical" in the DIY sense. iFixit's instructions were easy to follow, and there were only seven internal screws to remove, which were easy to replace.
What I found a bit confusing was that the iFixit website instructions end at the point where you remove the old battery. The only instruction in the conclusion was to follow the previous steps in reverse order. It was not very difficult to do, but I would have appreciated more guidance at that time.
One problem I encountered regardless of iFixit was that I removed the screen protector that was in place during screen removal. I noticed the hair cracks and was worried that I had damaged the screen myself, but thankfully it was undamaged.
Is it worth it?
It really depends on the age and value of the phone. If you, like me, bought a cheap used iPhone and just want to get it back up, it's a great way to revitalize old technology without spending a fortune. Keep in mind, however, that this would not be my headphone, nor did I buy it with my own money. For me the risk was low and if I had done it wrong and destroyed the phone it would not have been a big problem. You have to consider if you can really handle without it, just in case the worst happens.
If you're using a newer handset, like an iPhone X ($ 900 on Sprint) for example, I'd probably just take it straight to Apple. The savings you make by doing it yourself are not so great that it justifies the potential cost of damaging a more valuable phone.