How to check a refurbished phone's charging rate

A refurbished phone charges, but the percentage seems to climb unevenly or more slowly than expected. That does not automatically mean the battery is bad: the charger, cable, phone temperature, and current charge level can all affect the rate.

Use the Charger & Cable Test to compare charging speed in percent per minute. This gives you a repeatable way to compare setups, though it does not measure electrical power or certify battery health.

Compare the phone's charging rate

1. Open the Charger & Cable Test on the phone. It is available only when the browser reports battery information. If the test is not available, that alone does not mean the phone is faulty.
2. Connect the phone to a wall charger and cable you want to check. Use a normal wall outlet rather than a computer USB port or a hub, which may supply less power.
3. Leave the phone idle with its screen off for about 15 to 20 minutes. Note the reported charging rate in percent per minute. Keep the phone and charger in a cool, ventilated place.
4. Repeat the test with another cable or charger. Keep the outlet, phone, starting charge level, and test duration as similar as possible. Change one item at a time so you can tell what affects the result.

For a fair comparison, start each run at roughly the same battery level, ideally below 80 percent. Phones often slow charging as the battery gets fuller. Using the phone, running navigation, or playing a game during a test also adds power use and heat, which can make the result lower or less consistent.

What the result means

The rate is similar with both charger setups

If the readings are close across repeated runs, the charger and cable are probably not causing a major difference under those conditions. This does not prove the battery has its original capacity, but it makes a single bad cable less likely to explain the behavior.

One cable or charger is consistently slower

That setup is delivering less useful charging to the phone, or the phone is limiting it. Try the slower cable with a different compatible charger, then test the faster charger with the other cable. If the slow result follows one part, replace that cable or charger with a reputable compatible one.

The rate changes from one run to the next

First compare the conditions. A higher battery level, a warm phone, active apps, or a different outlet can change the rate. The phone may also adjust charging as its battery fills. Repeat the test from a similar charge level with the screen off before treating a changing reading as a fault.

The browser cannot show a charging result

The browser may not provide the battery information the test needs. Battery reporting is limited on some phones and browsers, including many iPhone browser setups. Try another browser if one is available, but do not treat a missing test as evidence that the charging hardware is broken.

How to check the phone and charging setup

1. Check the charging connection. Remove the cable and reconnect it firmly at both ends. Check the phone port for visible lint or damage, but do not push metal tools into it.
2. Try a different cable. Use a cable that supports charging and is in good condition. A cable can charge slowly even if it still works for basic tasks.
3. Try a different compatible wall charger. Use a charger that supports the phone's charging standard. A higher wattage printed on a charger does not guarantee the phone will draw power at that rate.
4. Check the phone's battery settings. On Android, open Settings › Battery and check for charging limits, battery protection, or adaptive charging options. The names and locations vary by manufacturer. On an iPhone, open Settings › Battery and review the battery health and charging options available on that model.
5. Let the phone cool down. Unplug it and let it return to room temperature if it feels unusually warm. Avoid testing in direct sunlight or under bedding. Heat can cause a phone to reduce charging speed.
6. Restart the phone and retest. A restart can clear a temporary software problem. After it starts, leave it idle and repeat the comparison using the same charger and cable.

When the phone may need service

Suspect a phone-side problem if several known-good, compatible charger and cable combinations all charge slowly under the same cool, idle conditions, or if charging repeatedly stops when the connector is still. If possible, compare with another phone that supports the same charging equipment, but remember that different models can charge at different rates.

Stop charging and arrange service if the phone's battery or case is swelling, the port looks damaged, or the phone becomes dangerously hot. Do not press a swollen case flat or keep repeating charging tests. For a recently refurbished phone, contact the seller or refurbisher while the return or warranty period is still active.

What percent per minute can tell you

The test compares how quickly the displayed battery percentage rises. It is useful for spotting a repeatable difference between two charging setups, but it is not a wattmeter. It cannot tell you the exact power reaching the battery, the battery's original capacity, or whether the charger meets electrical safety standards.

Battery percentages are rounded, and charging speed is not constant from empty to full. A short test can therefore look uneven even when the phone is working normally. Compare repeated runs at similar charge levels instead of relying on a single number.