If your phone now dies by lunch when it used to last the whole day, the battery is almost certainly wearing out.
The clearest signs are fast drain, sudden shutdowns at 20–40%, a jumpy percentage, slow charging, excess heat, and — the urgent one — a swollen or lifting screen.
Most phone batteries last about two to three years, but heavy use, heat and constant top-ups during load shedding can push them to that point sooner.
The good news is that battery failure usually announces itself long before the phone stops working completely. If you spot the signs early, you can replace the battery while the rest of the device is still healthy — and avoid the cost of a new phone.
Here’s how to check it before you spend a cent.
The 6 signs your phone battery is on its way out
A single odd day doesn’t mean the battery is dead. But when two or more of these keep showing up, the pattern usually points to the battery.
1. It drains far faster than it used to
This is the most common signal. If you’re reaching for the charger mid-morning when you once made it to bedtime, capacity has dropped.
A healthy phone loses maybe 10–20% over a normal day of messaging, maps and the odd video. If it falls off a cliff — 100% to 30% by 11am — the cells are struggling to hold charge.
2. Sudden shutdowns, even with charge left
Your phone shows 30%, then just dies. Or it switches off at 20%, sometimes higher.
Older lithium-ion cells can no longer deliver stable voltage, so the phone powers down even when the meter says there’s life left. This is different from a flat battery — there’s charge, but the battery can’t push it out fast enough.
3. The percentage jumps around
Watch the number: 40% → 15% → 28% in a few minutes. That erratic behaviour means the battery can’t accurately measure what’s left.
As cells degrade, the battery management system loses its grip on true capacity. A steady, predictable drop is normal; a jumpy one is a warning.
4. Slow charging, or it stalls at a percentage
If a full charge now takes hours longer than when the phone was new, the battery may be to blame. The same goes if it stops at 80–90% and won’t climb.
If the battery itself is the problem, the slow-charge symptom persists no matter which cable you try. One caution: a worn charging cable or a lint-packed port causes the same symptom, so test with a known-good cable first (more on that below).
5. It runs hot during normal use
A little warmth while gaming or video-calling is fine. But if the phone gets uncomfortably warm just scrolling WhatsApp or taking a call, the battery is working harder than it should.
That extra effort generates heat as a by-product. Heat and battery wear feed each other, so this one tends to get worse.
6. The screen or back is lifting — stop using it
If the screen is separating from the frame, the back panel bulges, or the phone won’t lie flat on a table, the battery is swelling. This is a safety issue, not just a performance one.
Safety first: If you suspect swelling, stop charging immediately, power the phone down, and keep it away from anything flammable. Do not press, bend or puncture the battery. Take it to a repairer or a battery recycling point. A swollen cell can catch fire if damaged.
What happens if you ignore a failing battery?
A worn battery does not get better on its own. At first it is just annoying — you carry a cable everywhere and hunt for plugs.
Over time, the phone may start throttling the processor to protect itself from unstable voltage, which makes apps feel slower and the camera take longer to open. Sudden shutdowns become more frequent, and if the phone dies while you are busy, you risk losing unsaved work or missing an important call.
In the worst case, a swollen battery can damage the screen from underneath, push the back cover off, or create a fire risk. Catching the problem early means you replace a cheap consumable part instead of dealing with a cracked display or a dead device.
How to check your battery health yourself
You don’t need an app or a technician to get a rough read. Both major platforms give you a window into battery condition.
On iPhone
- Open Settings → Battery → Battery Health & Charging.
- Look at Maximum Capacity. A new phone shows 100%; below about 80% is the usual “time to think about a replacement” mark.
- If you see a Service message at the top, the system has flagged the battery as significantly degraded.
On Android
It varies by brand, which is frustrating. Some phones (many Samsung models) show battery info under Settings → Battery or Device Care, and the Samsung Members app has a battery diagnostic. Others expose a figure through a dialler code such as *#0228#. If your phone shows no clean percentage, fall back on the symptom checklist above — it’s a reliable substitute.
| Reading | What it usually means |
|---|---|
| iPhone max capacity 80%+ | Generally fine for most users |
| iPhone max capacity below 80% | Worn; replacement worth considering |
| Android “Service”/poor diagnostic | Same ballpark — investigate |
| No clear figure | Judge by symptoms (drain, shutdowns, heat) |
How long should a phone battery last?
Most lithium-ion phone batteries are good for roughly 300 to 500 full charge cycles, which works out to about two to three years of daily use. A “cycle” is one full 100%-to-0% drain, or two half-cycles (two 100%-to-50% days). Charge it twice a day and you’ll hit that limit in closer to a year.
Heat is the quiet killer. Leaving the phone on a sunny dashboard, gaming while it charges, or keeping it in a hot bakkie cabin all shorten lifespan faster than the calendar alone would. Cheap, uncertified chargers add unstable power on top of that.
South African conditions that wear batteries faster
Local conditions matter more than the spec sheet suggests.
Load shedding. When Eskom’s rolling blackouts hit every few hours, we top up constantly in short bursts. That actually suits lithium-ion better than deep 0–100% cycles — but only if you keep the band sensible. Aim to charge in the 20–80% range and avoid parking at 100% overnight. The mini-cycles from load shedding are fine; the heat from charging through them is what you watch.
Heat. South African summers are hard on batteries. A phone left on the dashboard or used for navigation in direct sun can hit temperatures that permanently knock down capacity. Even a phone case can trap heat, so removing the cover during long charging sessions helps. Give it airflow, and skip heavy gaming while it’s plugged in.
Power banks are your load-shedding friend — but buy carefully. A decent power bank lets you top up between outages without stressing the phone’s own cells. Look for one with the right output for your phone, a recognised brand, and clear capacity markings. Avoid no-name units from market stalls; cheap power banks can deliver dirty power or swell themselves, turning one battery problem into two.
Counterfeit and bargain chargers. Market stalls and unknown online listings sell chargers and cables that over- or under-deliver current. Unstable power stresses the battery and can damage the port. Stick to the original charger or a certified replacement.
Battery problem, or just the charger or port?
Before you blame the battery, rule out the look-alikes — they’re common and cheaper to fix.
- Try a different cable and charger you trust. Many “battery” complaints vanish with a decent cable.
- Inspect the charging port under good light. Pocket fluff compacts in USB-C and Lightning ports and stops the plug seating. Clean gently with a wooden toothpick or other non-metal tool — never metal.
- “Only charges at a certain angle” almost always means the port, not the battery.
- “Only works while plugged in, dies the instant you unplug” points at the battery.
If a known-good cable and a clean port don’t change anything, the battery is the likely culprit.
When replacement makes sense (and when it doesn’t)
If the rest of the phone is sound — screen intact, camera fine, no board faults — a fresh battery is one of the best-value fixes around. It typically restores daily runtime and can bring back lost performance speed, because phones throttle the processor when the battery is weak.
For context, South African repair shops often quote roughly R700 to R4 000 for an iPhone battery swap depending on the model, while a DIY battery plus a basic toolkit runs a fraction of that. (Those are third-party shop prices for illustration only — we’re not quoting our own range here.) Whether you do it yourself or use a pro, the battery itself is a wear item; replacing it is normal maintenance, not a failure.
If the phone also has a cracked screen, failing camera or board damage, weigh the total cost against a refurbished upgrade before sinking money into the battery alone.
FAQ
At what percentage should I replace my phone battery?
On iPhone, Apple flags replacement around 80% maximum capacity with a Service message. It’s a guide, not a rule — if you see shutdowns at 85%, replacement may help sooner; at 78% with light use, you might wait. Android has no single number, so judge by symptoms.
Can a phone battery swell without warning?
Yes. Swelling comes from gas building inside the cell as it ages or after damage, and it can start with no obvious performance signs. Any lifting screen or bulging back is the warning — act on it the moment you notice.
Does load shedding damage phone batteries?
Not directly. The constant top-ups actually suit lithium-ion if you stay in the 20–80% band. The risk is heat from charging during outages and deep discharges if you let the phone hit 0% between cuts. Keep it topped and cool.
Why does my phone slow down when the battery gets old?
Both iOS and Android can throttle the processor when the battery cannot deliver peak voltage reliably. It is a safety measure to stop sudden shutdowns. A new battery usually restores the original speed.
Can I replace the battery myself?
If you are comfortable with small screws, plastic prying tools and following a guide, many batteries are user-replaceable. For modern iPhones and sealed Android flagships, the job is more delicate — one wrong move can tear a flex cable or break water resistance. If you are not confident, use a professional. Either way, always dispose of the old battery at a recycling point.
How can I make my phone battery last longer?
Keep charge levels between roughly 20% and 80% when you can, avoid leaving the phone in a hot car or in direct sunlight, and use original or certified chargers. Close battery-hungry apps you are not using, lower screen brightness, and turn off features like GPS and Bluetooth when you do not need them. In South Africa, topping up during load-shedding windows is fine — just don’t let the phone bake while it charges.
Is it worth replacing the battery on an old phone?
Usually yes, if the rest of the phone is healthy. A new battery can add one to two years of useful life at a small fraction of a new phone’s cost. If the device has other faults, compare the total repair bill to a refurbished replacement first.
Discrepancy Notice: Our online shop is still under preparation. Product prices, availability and shipping options are subject to change. This article is for informational purposes only — please contact us at support@potatotech.co.za for the latest information.
Discrepancy Notice: Our online shop is still under preparation. Product prices, availability and shipping options are subject to change. This article is for informational purposes only — please contact us at support@potatotech.co.za for the latest information.
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Discrepancy Notice: Our online shop is still under preparation. Product prices, availability and shipping options are subject to change. This article is for informational purposes only — please contact us at support@potatotech.co.za for the latest information.
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