How to compare battery drain before and after updates

Your laptop, tablet, or phone seems to lose charge faster after an update. A single battery estimate can be misleading, though: screen brightness, background activity, and the work you do all affect how quickly the charge falls.

Compare two sessions under similar conditions instead. The Battery Meter shows charge level, charging state, time left, and drain rate, so you can record a baseline before an update and check it again afterward.

Compare battery drain fairly

Open the Battery Meter before the update, while your device is unplugged. Note the charge level and drain rate. If the tool does not appear, your browser or device may not report battery data to websites.
Choose a starting charge level you can repeat, ideally within about 5 percentage points on both tests. Use the device unplugged, and keep the same power mode, screen brightness, Wi-Fi connection, and apps open.
Use the device in a consistent way for 30 to 60 minutes. For example, browse the same kinds of pages or play the same local video. Avoid changing between heavy gaming and idle time, since that makes the readings hard to compare.
At the end, note the charge level and the drain rate shown by Battery Meter. Also write down how long you tested and what you did. The tool does not keep a before-and-after report for you, so save the notes yourself.
After the update finishes, restart the device and repeat the test with the same starting charge range, settings, apps, and activity. If the update is still downloading or apps are still syncing, wait until that work has settled first.

Run each test for at least 30 minutes. Battery percentages are rounded, and a short session may show no change or a sudden one percent drop. A longer session gives you a more useful comparison. If the results look very different, repeat both sessions once before drawing a conclusion.

What the result means

The drain rate looks similar

If the displayed rate and the percentage lost over the test are close, the update probably has not caused a clear change in everyday battery use. Small differences are normal because background work and the battery estimate can vary from one session to the next.

The device drains faster after the update

A higher rate in a matched test is a reason to investigate, not proof that the update damaged the battery. The system may be finishing downloads, rebuilding its search index, syncing files, or running apps that were updated at the same time. Repeat the test after those tasks stop.

The drain rate changes while you watch

The displayed rate is an estimate, and it can change when the screen, processor, or background apps use more or less power. Compare the full test period and the amount of charge lost, rather than treating one moment's reading as the result.

Battery Meter does not show battery data

Some browsers and devices do not make battery information available to websites. Battery Meter appears only on devices whose browser reports a battery, such as some laptops, tablets, and phones. Try another supported browser on the same device. If the data is still unavailable, use the battery information in your device's system settings instead.

How to reduce unexpected drain

Give the update time to finish. Restart the device, leave it connected to power while downloads and app updates complete, then test again later. A major operating system update can trigger extra background work for a while.
Check which apps are using power. On Windows 11, open Settings › System › Power & battery › Battery usage. On a Mac, open System Settings › Battery and look for apps using significant energy. Close or update an app that stays busy when you are not using it.
Match your power and display settings. On Windows 11, check Settings › System › Power & battery for Power mode and Battery saver. On a Mac, check System Settings › Battery for Low Power Mode. Keep these settings the same during both tests, then adjust them if you want longer battery life.
Reduce screen brightness for a longer runtime. A bright screen can use a noticeable amount of power. Use the same brightness for your comparison, then lower it if you want to reduce drain during normal use.
Install follow-up updates. Check Settings › Windows Update on Windows 11 or System Settings › General › Software Update on a Mac. Updates to the operating system or apps can address problems that appear after an upgrade.

When the battery may be wearing out

A battery loses capacity as it ages. It can therefore run down faster than it used to, even when the update is not the cause. If the same test shows consistently high drain after background activity has stopped, check your device's battery health information or run the manufacturer's diagnostic. A swollen battery, sudden shutdowns, or a device that becomes unusually hot needs prompt attention. Contact the manufacturer or a repair shop about replacement rather than continuing to use a swollen battery.

Why the charge percentage is not enough

The displayed percentage estimates how much charge remains, not how many minutes you will get from it. The same percentage drop can represent very different workloads: streaming video, an idle desktop, and a game do not use power at the same rate. For a useful comparison, keep the workload and settings steady, and use the drain rate as another clue alongside the change in charge level.