How to compare charging during app updates

Your phone is plugged in, but the battery seems to charge slowly while apps are downloading or installing. That does not automatically mean the charger or cable is failing. Updates can make the device use more power and generate heat, which can reduce how quickly the battery gains charge.

Compare the same setup at rest and during an update with the Charger & Cable Test. The test reports charging speed in percent per minute, so you can see whether the difference appears when the update is running.

Compare charging with and without an update

Open the Charger & Cable Test on the device you want to check. The browser must report battery information for the test to work.
Use the charger, cable, outlet, and device position you want to compare. Start when the battery is at a similar level each time, for example around 30 to 50 percent. Charging often slows as the battery gets fuller, so comparing different battery levels can mislead you.
With no app update running, leave the device in a consistent state. Keep the screen on at the same brightness, and avoid using other demanding apps. Note the charging speed in percent per minute. The Battery Meter can also show the reported charge level and charging state.
Start an app update while leaving the charger and cable connected. Keep the test page open in front, and note the charging speed while the update downloads and installs. If the browser pauses when sent to the background, keeping it visible helps make the comparison more useful.
Repeat the comparison at a similar battery level. If possible, compare another charger or cable using the same update conditions, changing only one part at a time.

App updates do not always use the same amount of power throughout. A download uses the network, while installing may use the processor and storage. Write down whether the update was downloading or installing when the reading changed.

What the result means

The charging rate falls during the update

The device is likely using more power while it works, leaving less of the charger's available power to raise the battery level. Heat can also make a phone or tablet reduce charging speed to protect the battery. If the rate returns to its earlier level after the update and the device cools, that points to workload or temperature rather than a failed charger.

The rate stays about the same

The update is not changing the reported battery charging rate by much in this test. That does not mean the update uses no power. A charger may supply enough power for both the device's activity and battery charging, or the change may be too small to show clearly in a percentage-based reading.

The rate drops to zero or the device says it is not charging

Check whether the cable is loose, the charger is recognized, or the device has become hot. Some devices temporarily pause charging at a temperature limit or when a battery protection feature is active. If charging resumes after the update ends or the device cools, repeat the test before replacing anything.

The result changes between repeats

Battery percentage is an estimate, and the reported rate can vary with battery level, temperature, screen use, network activity, and background tasks. Treat the test as a comparison under matching conditions, not a direct measurement of charger wattage. A single short reading is not enough to prove a fault.

How to make the comparison fair

Match the starting battery level. Compare readings in roughly the same percentage range. Avoid comparing a low battery in one run with a nearly full battery in another, because charging commonly tapers as the battery fills.
Keep the setup unchanged. Use the same wall outlet, charger, cable, and device orientation for the idle and update runs. When comparing cables, change only the cable. When comparing chargers, keep the cable and outlet the same if possible.
Keep other activity steady. A video call, game, hotspot, or bright screen can add power use. On Windows 11, check Settings › System › Power & battery. On a Mac, check System Settings › Battery. These pages can help you review battery and power behavior, though they do not identify every app's moment-to-moment power use.
Let the device cool before another run. If it feels hot, stop the comparison and let it cool in a shaded, well-ventilated place. Remove a thick case if it traps heat. Do not put the device in a refrigerator or freezer.
Check charging protection settings. On iPhone, look under Settings › Battery for charging options. On Android, look under Settings › Battery, though the exact names vary by manufacturer. A charging limit or optimized charging feature can make the battery wait or slow down near its limit.
Pause updates for a charger-only check. If you want to judge the charger without the extra workload, wait for updates to finish, then repeat the test with the device idle. A slower result only during updates is not, by itself, evidence of a bad cable.

When the charger or cable may be faulty

Suspect the accessories if charging remains unusually slow with the device cool and idle, especially if the same device charges faster with another known-good charger and cable. Test one replacement at a time so you can identify which part changes the result. Check for bent connectors, fraying, looseness, or a plug that only works at a particular angle. Stop using damaged accessories.

If the device charges slowly with multiple compatible chargers and cables, the port, battery, or charging circuitry may need service. Use the manufacturer's approved charger specifications and contact support or a repair shop, especially if the device gets unusually hot, the port is damaged, or charging repeatedly stops.

The Charger & Cable Test compares reported battery charging speed, not the electrical safety or exact wattage of a charger.