/ Technology

Is it time to replace your iPhone’s battery?

Has your old phone become frustratingly laggy? It might be time for an expensive upgrade… but is there another option?

My iPhone’s been really struggling lately: apps take a noticeable time to open and often crash, it’s laggy when I’m typing and taking spur of the moment photos just isn’t possible anymore (having to hang around for 5 or 6 seconds for the camera to start working).

I’d been aware for some time that I really needed to upgrade my phone, which I bought in 2015, but had been putting it off: nearly £1,000 for a new iPhone seemed a horrendous price to pay (I always buy my phone outright and get a pay-as-you-go contract).

Read: Which? Best Buy mobile phones

So I struggled on with my four-year-old phone, convincing myself that slightly longer load times and an inability to take photos were a small trade off for what was basically a functional phone.

Power problem

Then one day looking through settings, I came across information on my phone’s battery, and this message:

‘This iPhone has experienced an unexpected shutdown because the battery was unable to delvier the necessary peak power. Performance management has been applied to prevent this from happening again.’

With a bit more research I worked out what ‘performance management’ meant: my phone’s processing power was being limited by the operating system because my battery was degraded.

Although I’d had the phone since 2015, it hadn’t occurred to me that the battery might be affecting performance – I didn’t know it could.

But in fact it turns out that Apple deliberately slows processing speeds in older phones to prevent iPhones from randomly shutting down due to lack of juice.

This makes sense, but it wasn’t ever exactly made clear to me that the phone had been locked at a lower processing speed: I’d thought my phone was obsolete rather than just limited.

Apple juice

With this knowledge in mind, I realised I had a new option open to me (beyond splashing out a grand on a new phone): I could simply get my current phone’s battery replaced. So that’s what I did.

I booked my phone into a third party repair centre near where I work the next day for a battery replacement. It was cheap and hassle free – costing £35 for parts and labour and taking a couple of hours.

The only slightly laborious thing was I had to backup my phone before and restore it afterwards – they wipe the memory when repairing it (but you have to go through this process with a new phone as well) .

And is the phone running at a higher performance now? Yes, significantly. Opening and switching between apps is almost instantaneous again and there have been no crashes: not bad for a four-year-old phone.

Repair, recycle, reuse

My regret is that Apple never made it clear to me that my phone had been limited and that getting a battery replacement was necessary to ‘unlock’ the processing power I’d lost.

Apple confirmed in 2017 that for a year they’d been slowing iPhones in order to ‘smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions.’

As far as I remember, this news was never passed on to me – and in my opinion it probably should have been.

But it makes sense from their perspective I suppose – Apple CEO Tim Cook recently said that the company’s sales of new phones had been affected by ‘some customers taking advantage of significantly reduced pricing for iPhone battery replacements.’

So it looks like other people are getting their iPhones repaired rather than buying new ones, which can only be a good thing in terms of sustainability – and avoiding unnecessary new purchases.

But what do you think? How old is your mobile phone – does it still work well for you? Will you be getting your iPhone repaired after reading this?

How old is your mobile phone?
Loading ... Loading ...
Nick says:
25 January 2019

I’ve had increasing problems reading The Times website on my iPad and it’s getting worse. Do you think the battery issue could also be affecting the processing power of iPads?

If other websites are working fine then it’s unlikely to be a problem with the iPad. Watching iPlayer or other video content would place greater demands on the processor etc. There is a FAQ for the Times app but only those who are registered can access this information.

Well its possible Nick ,to make sure get the battery tested for efficiency but its not the only thing it could be .
Have you checked the auto dim feature ? .
There could be screen problems like backlight bleeding and other problems .
Take it to a dealership and get them to test the battery first though.

Nick: go to system prefs / general / screen brightness and check what the position is. Sometimes it resets itself after a major update.

I feel a little late to this article, and I’m definitely one who really needs to consider whether to upgrade his mobile phone (from an iPhone 6) or have the battery replaced (which would be the third time). Decisions, decisions!

Great battery improvement tips on the comment thread, and we have plenty of tablet/mobile device advice on Which? Tech Support’s website 🙂

Hi Andrew – Long time no see. Wouldn’t it be nice if you could just pop in a replacement battery and maybe carry around a spare in case it was not convenient to charge the phone?

DerekP says:
21 March 2019

I’m afraid luxuries like that are reserved for those of us who use nice cheap Alcatel (or similar) smart phones.

Now don’t be provocative telling about your £25 smartphone yet again. 🙂 I’m more impressed in you keeping your Zanussi washing machine for more than 30 years. Phones are still advancing quickly whereas that’s not so much the case with washing machines.

Can you please advise us on the security risk of using a phone that can no longer be updated, assuming it would not be used for banking?

Wavechange, I’m not really an expert on mobile phone security.

That said, any personal computing device that is no longer receiving updates is, in principle a greater security risk than one that is being updated.

One specific instance of this would be that, once any new vulnerability is discovered, it ought to be remedied by means of updates to support devices. But, with some rare exceptions, corresponding updates won’t be rolled out to unsupported devices.

With regard to specific threats, I did manage to find a some interesting articles:




In general, it looks as though the risks would be lowest for iPhone users.

The potential threats will also vary according to what apps the phone is used for. I doubt that browsing W?C with an unsupported device would generate many risks, whereas wide ranging surfing and downloading obscure apps would pose much higher risks, as too would extensive use of public wifi.

I accept the disclaimer and will look at the links. 🙂 Sadly, the only people I know with older phones know even less than me about security.

I’ve long since stopped using public WiFi, not only because of the established risks but because improved network coverage has removed the need.

Information about ‘vintage and obsolete’ Apple produces is here: https://support.apple.com/en-us/HT201624 It’s a pity that Apple does not do what Microsoft does and publish information about software lifecycle well in advance.

Yes, long time no see wavechange and all! 100% agree, but I can’t imagine it happening. Luckily we can use power banks to charge on the go, although they’re a bit of a nuisance to carry about (including the USB wires).

@katebevan Perhaps a future report for Which? Computing? 🙂

I bought a power bank when my iPhone 5s battery seemed to be failing. I’ve not really needed it for the phone but it keeps the sat nav working on long journeys without needing a cable to the power socket.

I did notice that Which? found power banks fell short of their stated capacity, which is disappointing: https://www.which.co.uk/reviews/mobile-phones/article/best-portable-power-bank-chargers

David says:
29 January 2019

I have a samsung Galaxy A3. about 3 years old. When i am abroad it does not work. Have put roaming feature on. Had thsi happen whenever i have used it abroad, always within EU. is this a problem with this phone or am I doing somthing wrong,

DerekP says:
29 January 2019

Duncan, t

That link doesn’t seem to work. This one might do better:


I’ve looked at the helpforsmartphone.com roaming guides for both A3 and A3-2016 models and they seem to be the same, so either should do for David.

In my experience, most Android phones will automatically roam for voice calls, but, for internet uses, they may need to have data roaming turned on, as per the above guides.

David says:
31 January 2019

thanks guys, discussed the matter with carphone warehouse upshot is got a new phone

On the previous page of this Convo I reported that the battery of my iPhone seemed to be failing over Christmas. I managed to improve the performance with a little housekeeping but since Derek had suggested a useful video and Ian suggested where to buy the battery from.

Replacing the tiny screws needed patience and after five years the battery was stuck very firmly in place, but the phone is back together and working. The cost of replacing the battery was £16.20, including some sticky tape and small tools.

With some phones it is necessary to remove the screen to change the battery, which requires heat to be applied at the edges to soften the glue. I would not even try.

After 38 hours my phone is down to 25% charge and it was used quite a lot yesterday. Hopefully it will not need any further attention until it is pensioned off. I cannot remember how long the battery lasted when the phone was new.

George says:
16 February 2019

I would not describe myself as a “tree hugger”, but it does concern me how many manufactures fail to understand the fact that a satisfied user of older equipment, is probably one of their best selling tools.
“I’ve had an XYZ phone for ##years, and it’s never let me down – so yes I would definitely recommend an XYZ for you!” is to me a far better way to promote sales.

Interestingly, It’s thought to be the major reason why Apple iPhone sales have slowed. Because Apple gear is extremely reliable and lasts for a long time, users are not so keen to upgrade as they used to be, partly because the newer models aren’t offering much in the way of ‘must have’ new features but mainly because older Apple gear still works perfectly.

We have, between us, two iPhones: a 6 and a 7, and there’s really no need to upgrade, since both do everything we need them to do. Apple computers have the same issue: I have several, perfectly functioning Apple Macs lying around, simply because they’re not fast enough to handle the latest in Video processing with the speed I need. I re-purpose them into running a media server, DVD extraction and a acting as music servers for the house.

DerekP says:
16 February 2019

My 11 year old MacBook still works great (except for its letter box DVD drive).

I’ve just given it to my girlfriend’s daughter, as a swap for a Dell Latitude ultrabook.