New cable charging slowly? Test it before a festival

You bought a new charging cable for a festival, but your phone still seems to be gaining battery slowly. A short check at home can show whether the new cable charges more slowly than your usual setup, while there is still time to try another one.

The Charger & Cable Test measures charging speed as a percentage of battery per minute. Compare one cable with another, changing only the cable so the result is useful.

Compare your new cable with your usual one

Open the Charger & Cable Test on the device you plan to take. If the tool is not available, the browser may not report battery information for that device.
Connect your usual cable to the same charger and wall outlet you plan to use with the new cable. Keep the device in the same place and note its battery percentage.
Let the device charge while idle for a few minutes, then check the rate shown by the test in percent per minute. Note the reading and the starting battery level.
Swap only the cable. Keep the charger, outlet, device, screen use, and approximate starting charge the same, then give the new cable a few minutes to settle and note its rate.
Repeat each setup once if the readings jump around. Compare the rates from similar battery levels rather than relying on one brief reading.

For a fair comparison, do not use the phone for one test and leave it idle for the other. Screen brightness, games, navigation, video, and background updates all use power while the device charges, which can make the battery percentage rise more slowly.

What the result means

The new cable has a similar rate

If both cables charge at about the same rate under similar conditions, the new cable is probably keeping up with your usual one for this charger and device. It does not prove the cable supports every charging feature or speed, but it is a useful practical comparison for your festival setup.

The new cable is consistently slower

A repeatable difference suggests the new cable, its connection, or its compatibility with the charger may be limiting charging. Check that the cable is fully seated and try it with another compatible charger before deciding the cable itself is the cause.

Both cables charge slowly

The charger, power source, device temperature, or the phone's own charging behavior may be the limiting factor. Many devices slow charging as the battery gets fuller or when the device is warm. Compare again at a similar charge level, while the device is cool and idle.

The rate changes from one reading to the next

Small changes are normal. Battery percentage is not a precise measure of energy entering the device, and charging speed can shift as the device adjusts power. Look for a repeated, clear difference instead of treating a brief dip as proof of a faulty cable.

The tool is not available

The browser or device may not expose battery data to web pages. Battery Meter and Charger & Cable Test appear only on devices whose browser reports a battery. Use the device's charging indicator and compare how much the battery rises over the same time, with the same setup and conditions.

How to fix slow charging

Reseat both ends of the cable. Unplug it from the device and charger, then reconnect it firmly. Check for lint or debris in the port, but do not push metal objects into it.
Try a different outlet. Connect the same charger and cable directly to another wall outlet. Avoid comparing a wall outlet with a low-power USB port on a computer or a crowded hub.
Check the charger's output. A cable cannot make a low-power adapter deliver more power. Use a charger that is compatible with your device, and compare cables using that same adapter. On a laptop, Windows 11 shows power and battery information under Settings › System › Power & battery; macOS shows battery information under System Settings › Battery.
Let the device cool and charge idle. Remove it from direct sun, stop navigation or video playback, and leave the screen off for a few minutes. Heat and active use can reduce the net battery gain.
Check charging settings. On an iPhone, open Settings › Battery. On Android, open Settings › Battery, or on some models Settings › Battery and device care › Battery. Check whether a charging limit or battery protection setting is affecting the charge target. Menu names vary by device.
Restart and test again. If the phone still reports charging inconsistently, restart it and repeat the comparison. On a laptop, use Settings › System › Power & battery in Windows 11 or System Settings › Battery on macOS to check whether it reports that it is charging.

When the cable or charger may be faulty

If the new cable is repeatedly slower with more than one compatible charger, while your usual cable works normally, stop relying on the new one for the festival. Return it or contact the seller if it is under warranty. Replace a cable that is frayed, has a loose connector, smells unusual, or becomes uncomfortably hot. Do not leave a suspect cable charging unattended.

If both cables are slow with a known-compatible charger, the issue may be the charger, charging port, or device rather than the cable. If the connector only works at certain angles, avoid bending it to maintain contact. A damaged port needs professional repair.

What this test can and cannot tell you

The test reports observed battery gain over time, not the cable's exact wattage or electrical condition. The result depends on the charger, device, temperature, battery level, and what the device is doing. A good reading also does not verify that a cable meets a particular certification or is safe for every device.

Run the comparison at home before packing, and bring the cable and charger that gave you the more consistent result. The test measures charging behavior on your device, and it does not need you to upload photos or recordings.