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I have Macbook Air, Mac OS X El Capitan.

There is no warning box shown before the battery is near %15, like it did for Mountain Lion. So I can not notice and my computer goes sleep simply when the battery is off.

And even if it did I generally miss it because I use it external monitor attached to my Macbook Air. And because I play Spotify, I may miss the warning sound, too.

Is there warning box for low battery on El Capitan? If not, is there any utility or software that may help for external monitors and even playing music?

5 Answers 5

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Default Warning

The battery indicator in the menu bar will turn red when the battery is low. There will also be a critical low power warning when the computer needs to emergency shut down.

See Apple's About Mac notebook batteries page, in particular this section:

The low battery warning doesn't display

If you don't receive a warning when your battery has a low charge, generally reported at or under 15%, it may be because the battery menu bar icon is disabled. Follow these steps to enable the battery status menu item:

  1. Open System Preferences.
  2. Click Energy Saver.
  3. Enable the "Show battery status in menu bar" check box to display the battery status menu item.

Note: Portables using OS X Mavericks v10.9 or later display the low battery warning when the battery has approximately 10 minutes of power remaining. Earlier versions or OS X instead report it at 15% or less.

Third Party: Power Manager

Software such as Power Manager can be used to trigger scripts, sounds, and actions when the battery level drops:

Power down on battery remaining

More advanced abilities such as stopping music from playing and integrating the warning into your workflows is possible. Battery levels and changes are exposed through Power Manager's AppleScript interface.

Disclosure: I am an engineer who works on Power Manager. So, feel free to ask technical questions about the product.

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  • it's not quite relevant since the question is about alerts/notifications as it was before, not about the icon's color change. Besides, the icon is not visible when the manu bar is auto-hidden.
    – norlin
    Dec 17, 2018 at 9:55
  • @norlin which section do you not think is now relevant? Are you using the same macOS as the question or something more recent? Dec 17, 2018 at 10:52
  • Thanks, that was my issue. I used Coconut Battery, which has his own battery menu bar icon. So I deactivated the default one to not have 2 battery icons, which turned the warnings on low battery off. (These warnings shouldn't be coupled to the menu bar icon in my opinion…)
    – GG.
    May 12, 2020 at 16:07
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I'd really recommend Battery Medic

It supports notifications based on a battery threshold that you can set. And unlike most of the other apps that require you to pay for the battery alert feature it's completely free

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  • Does it warn even if the mac is plugged in? I use one dock to charge both of my laptops and sometimes my main laptop is using more than it is getting from the dock, so it loses battery even while plugged in, and doesn't warn and it just goes off.
    – nroose
    Aug 19, 2021 at 19:36
  • @nroose I believe it does warn even when plugged in. But the problem is that it only warns once - so if your battery drops below the threshold (say 10%) and doesn't go above it even after plugging in, it probably won't warn again even if it goes off. The battery needs to go above 10% at least once for the warning to trigger again Aug 25, 2021 at 11:16
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There's also a third party app BattMan, which can raise Notifications via Notification Centre and sound an audible alarm when the battery charge drops to certain percentage or time left on battery reaches a certain level (both user settable).

BattMan Screenshot

Full Disclosure: I'm the dev behind this app.

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  • 1
    A review points out the warning can't be set above 30%. I have a dodgy battery that cuts off at 33%, so I can't use it. Lucky I saw the review.
    – gbarry
    Aug 7, 2017 at 1:10
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I have Mac OS X Sierra, but the Battery Monitor app I just installed works great and allows you to set a notification threshold at an arbitrary percent for free. Tested it out and it works great.

Here's the app store link: https://itunes.apple.com/us/app/battery-monitor-health-status-battery-usage-information/id836505650?mt=12

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  • Battery Monitor keeps popping up ads for the other apps of the developer since the latest update.
    – user407499
    Feb 21, 2021 at 7:12
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Change low battery notification from 10% to 20% was marked as a duplicate of this (even though it's not), so I'll answer it here.

As the other answer points out, the low battery notification is generated by SystemUIServer when the inbuilt battery icon menu extra is enabled. On 10.8 to probably 10.12-ish (have not checked precisely) there is a binary /System/Library/CoreServices/Menu Extras/Battery.menu/Contents/Resources/lowBatteryWarning that is invoked by SystemUIServer which is the one that actually sends the notification to NC. The binary checks whether it's called by SystemUIServer before executing.

While it's easy to replicate the notification behavior with external applications which monitor battery percentage, I suppose if you really wanted to do this "natively" you could disable SIP and inject code into SystemUIServer to manually trigger the alert. The trigger for alert is the result IOPSGetBatteryWarningLevel(), not based on the percentage directly, and I wouldn't recommend patching that function directly since who knows what else in SystemUIServer might depend on it. Instead you should modify the calling method in BatteryExtra to add a tail-call that checks the current percentage and if so, invokes the binary.

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