5 signs your phone battery needs replacing (and what it costs)

The five signs

• It doesn't get you through the morning any more, on the same usage as always.
• It shuts down suddenly at 20–30% — the battery can no longer deliver stable voltage under load, so the phone gives up early.
• It charges slowly, gets unusually warm charging, or the percentage jumps around.
• Battery health reads poorly: on iPhone, Settings → Battery → Battery Health — below about 80% is replacement territory. Most Android phones expose similar information in settings or via the manufacturer's support app.
• The back or screen is lifting away from the frame. That's a swollen battery — see below, today.

A swollen battery is not a "keep an eye on it" problem

If the case is bulging or the screen is being pushed out, the battery has begun producing gas internally. Don't press it, don't puncture it, stop charging it, and bring it to a repair shop as soon as you practically can. A swollen lithium battery is a genuine fire risk — this is the one fault on this page we treat as urgent, and we'll prioritise it in the shop accordingly.

Why batteries wear out

Lithium batteries age chemically with every charge cycle, and heat accelerates it. Most phone batteries are designed for roughly 500–800 full cycles before capacity drops meaningfully — for a heavily used phone, that's around two years. It's normal wear, not a fault, and it's also the cheapest major component in the phone to renew.

What a replacement costs

Battery replacement at TikTech starts from £39, and on most phones it's done the same day — usually under an hour. It's the single most cost-effective repair there is: for a fraction of the price of a new phone, a device that was limping to lunchtime behaves like it did when it was new. Exact prices per model are on our repair pages.

Making the new one last

You can't stop chemical ageing, but you can slow it: avoid leaving the phone flat for days or parked on a charger at 100% around the clock, keep it out of hot cars and direct sun, use the optimised-charging setting your phone almost certainly has, and be suspicious of no-name chargers — the battery is only as safe as the electronics feeding it.