Why won't my MacBook warn me when my battery is about to run out anymore?
May 24, 2012 11:23 PM   Subscribe

My Macbook used to give me a low-battery warning before it went to sleep: now, before the battery indicator even turns red, it just powers down without warning, and I'll lose anything I had open and was working on. What happened?
posted by BuddhaInABucket to Computers & Internet (13 answers total) 2 users marked this as a favorite
Hopefully someone can tell you what's wrong, but if you want a warning in the meantime: BatteryDeley.
posted by vegartanipla at 11:35 PM on May 24, 2012

Is the battery/Macbook a few years old? I've seen this a few times with batteries that are ready to be replaced.
posted by no regrets, coyote at 11:36 PM on May 24, 2012

If it's powering down without warning, and you're losing data, are you really sure it's the battery being depleted? That sounds a lot like an over-heating shutdown.

Next time it happens, turn it over for a few minutes, and then restart it and check if the battery still has charge. That should show that it was a heat-related shutdown.
posted by pompomtom at 11:39 PM on May 24, 2012 [3 favorites]

You need a new battery.
posted by w0mbat at 12:17 AM on May 25, 2012 [3 favorites]

Depending on what model you have, exactly, you may be able to re-calibrate the battery. If your battery is old, it may or may not do much, but it's worth a try.
posted by xil at 12:25 AM on May 25, 2012

As the battery ages the whole battery state monitoring / auto-shutdown thing can get out of whack. When it's well on the way to being knackered, it's not unusual for Macs to often not come out of hibernate properly.

I also get the distinct feeling that there's something about MS Office apps that increases the likelihood of hibernate not working, but that's only a personal impression.

If it's one of the older models with a removable battery, turn it over and press the little button on the battery - there's 5 LEDs that give an indication of charge. A single one flashing, or none at all, indicates a flat battery. All 5 flashing = dead or faulty battery.

If the battery is flat, go through the calibration procedure here, followed by the SMC reset procedure here, and see if that helps things.
posted by Pinback at 12:32 AM on May 25, 2012

Along with what everyone else is saying, sometimes the batteries will internally just fail. I had a battery that, when it reached about 70%, the machine would just lose power. Cold. No warning, no safe shutdown. Didn't matter what I did. And even though I tried to recalibrate it, it would die at the same point during the calibration!

So... if it always dies at the same point and recalibrating doesn't help then your battery is bad and needs to be replaced. Mine failed while the laptop was still under AppleCare, and the battery cycle count was very low, so Apple replaced it w/o charge. But if you're batter has a high cycle count or you aren't under warranty anymore, you'll probably have to buy a new one yourself.
posted by sbutler at 12:41 AM on May 25, 2012

When the same thing happened to me it meant I needed a new battery.
posted by sparrow89 at 1:10 AM on May 25, 2012

Adding in that it's your battery needing to be replaced. My Macbook Pro has been great for the past five years, except that I've had to replace its battery twice. I'm looking at a third time now, it's dying again.
posted by InsanePenguin at 4:16 AM on May 25, 2012

Concurring that it's probably your laptop overheating. I had a laptop that kept shutting down randomly and thought it was a bad battery. Opened it up and the fan was clogged with cat fur, so the laptop was unable to cool down. So if you have kitties....
posted by Lobster Garden at 5:27 AM on May 25, 2012

An overheating laptop's fans would be spinning at top speed, and the machine would slow to a crawl before it just shut itself off.

Lithium batteries fail that way. You can "prove" it's the battery by noting whether the machine powers itself off the same way while running on the AC adapter. If it does not power itself off the same way, then overheating is not the reason it is shutting down unexpectedly. And that the battery probably is the reason.

The battery monitor can't actually know how much power is in the battery. It can only guess by measuring the voltage. On a fresh battery, the voltage gradually goes down and it scales that voltage to a percentage of remaining power. On a worn out battery, the voltage drops quickly, and ultimately so fast that the monitoring software doesn't have time to react.
posted by gjc at 7:05 AM on May 25, 2012 [1 favorite]

yup, you need a new battery.
posted by hollisimo at 9:55 AM on May 25, 2012

An overheating laptop's fans would be spinning at top speed, and the machine would slow to a crawl before it just shut itself off.

Not on a macbook. They just go *blink* when overheated.
posted by pompomtom at 4:06 PM on May 25, 2012

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