Why does my Macbook battery only last half as long now, but is still at 97% health?
January 8, 2010 8:33 AM   Subscribe

Why does my Macbook battery only last half as long now, but is still at 97% health?

My macbook (white) is 31 months old, and the battery has had 415 charge cycles. Fully charged, it only lasts about 2.5 hours now, whereas it used to last 5 hours. I know batteries have a finite life, so that's fine.

What I don't understand is that coconutbattery and battery health monitor both tell me that my battery is still at 97% capacity (4,881 mAh now, down from of 5,020 mAh original).

So if the battery capacity is still at 97%, why is it draining twice as fast? What's the relationship to the battery life?

Just want to understand how this works...

Thanks!!
posted by snailparade to Computers & Internet (14 answers total) 6 users marked this as a favorite
 
Over time computer batteries slowly decrease in capacity. About every year and half they need to be replaced. The battery capacity will still read 97%, but it's 97% of a much smaller number. Buy a new battery, they're pretty cheap.
posted by melissasaurus at 8:36 AM on January 8, 2010


Basically, the numbers are wrong.

See this.
posted by TheNewWazoo at 8:37 AM on January 8, 2010


This is what happens to laptop and cellphone batteries. They wear down over time. Depending on the battery, you could start to notice a degradation as quickly as 6-9 months, but after 18 months it usually gets pretty bad. 31 months is a long time. You need a new battery.
posted by jckll at 8:38 AM on January 8, 2010


Oh, but I did have the 3-year Applecare. So that may have played into it, despite the fact that all their documentation says it doesn't cover replacement batteries.
posted by InsanePenguin at 8:44 AM on January 8, 2010


Also, to chime in--I experienced the same thing with my MacBook battery over a similar timeframe. I know that batteries lose their ability to hold a charge, but I was somewhat confused because an app like Coconut Battery showed the health as being pretty good.

By all means--go to an Apple Store and have them double check--they use a proprietary program installed on a iPod that they use to boot up the machine. Their program showed that my battery was pretty well kaput.

Fortunately, they were very happy to sell me a new battery for $120! Everyone wins (except for me)! Hooray!
posted by Admiral Haddock at 8:46 AM on January 8, 2010


Did you remember to recalibrate your battery every so often?

FYI, you can get hold of Macbook batteries on Ebay (I got a new one for $48 delivered from Hong Kong). Be sure to check the part number (something like A1185, A1181 or MA561 etc.). It should be written on the battery somewhere.
posted by jonesor at 8:55 AM on January 8, 2010


2.5 hours from the original, nearly-3-year-old battery isn't bad at all.

I work with Macs for a living, I see plenty of worse batteries routinely. In my experience, poor battery performance starts becoming noticeable around 250 cycles, and over 400 would be a opportune time to replace it. See if you notice any improvement after recalibrating by following the steps on the KBase article TheNewWazoo linked to up-thread.

As for 3rd party supplies, I've used Newer Tech and BTI when Apple parts weren't available, usually after 5-7 years.
posted by now i'm piste at 9:01 AM on January 8, 2010


Just a note I actually ran into an issue with my (first gen) MBP where the battery casing actually warped a bit and caused issues with my trackpad (battery underneath was actually pushing up into the pad). I got a new battery for about $65. Its not an Apple branded battery but it seems to work fine.
posted by bitdamaged at 9:10 AM on January 8, 2010


As for what's on the iPod's and hard drives used for diagnostics at Apple corporate stores, I'll let someone else break confidentiality.

As for what most of the Specialists (which are independently owned) use, I imagine it's a combination of software diagnostics provided by Apple along with house-created service drives, containing an appropriate OS and related software tools such as Disc Warrior, Drive Genius, Tech Tool, Data Rescue, File Salvage, Onyx, Apple Jack, software update packages, etc.
posted by now i'm piste at 9:13 AM on January 8, 2010


Being a longtime PC user, I went to a Genius Bar over this. First thing the guy did after checking to see that my battery was about like yours (2.5 hours of battery, with sub 50 cycles and high percentage quality) was download the istat pro widget. After seeing that most of the hardware was ok, I was told to watch out for a few key things:

1) Watch the number of programs you have loaded. Each of those little pips in the Dock is costing you processor cycles which equates to battery usage. In particular, Firefox is a fine browser but it is also a resource pig - using Safari when you're on battery will buy you more time.

2) Make sure your programs are installed correctly in Applications and that you are not running any programs off of the disk image. Early on, I wasn't quite clear on that distinction.

3) Watch the desktop background switching. Having it cycle new images rapidly will be a slow drain. Wasn't my case, but the way he said it made me think he had seen it a lot.

4) Recalibrate it occasionally.

5) He was also against my putting the laptop to Sleep a lot, saying that it was hard on the drive and that the machine would sometimes wake up and if it was jostled during this time, I could be in for a crash. I completely do not understand why this would happen, but I'm just repeating 'cause a guy in a Genius t-shirt said it.
posted by Moonster at 10:00 AM on January 8, 2010


Just a warning not to buy batteries through Amazon, as they seem to be non-Apple-brand batteries. I bought one recently which had bulges in the top and a peeling bottom layer. I suspect it is a counterfeit or is rebuilt from bits and pieces of spare batteries. If you do decide to get one, better to buy it through an official Apple reseller.
posted by Blazecock Pileon at 2:16 PM on January 8, 2010


Thanks everyone for the input and info. I put in a new battery from Apple, calibrated it, and the time remaining is fluctuating wildly. 2 hours left, 3 hours left, 4 hours left, 1.5 hours left, 2 hours left, 3 hours left...all while I'm just sitting here typing with nothing else going on. Oh well, hopefully it gets a good amount of time.

& thank you for the tips about recalibrating occasionally, something I didn't do with my last battery (not intentionally anyway). I will be sure to do that.
posted by snailparade at 9:45 AM on January 9, 2010


2.5 hours from the original, nearly-3-year-old battery isn't bad at all.

I work with Macs for a living, I see plenty of worse batteries routinely. In my experience, poor battery performance starts becoming noticeable around 250 cycles, and over 400 would be a opportune time to replace it. See if you notice any improvement after recalibrating by following the steps on the KBase article TheNewWazoo linked to up-thread.

As for 3rd party supplies, I've used Newer Tech and BTI when Apple parts weren't available, usually after 5-7 years.
posted by now i'm piste at 12:01 PM on January 8, 2010


You probably need a new battery. BUT! Don't buy a new battery for your Macbook until you talk to someone at Apple. Twice I've gotten free batteries out of them. My MBP is going on 4 years old, two years in I complained about the battery and they sent out a replacement. Then, just last September when that one was dying I walked into an Apple store and told them my battery was fucked. She futzed around for a bit, then walked into the back and came out with a new battery. I think I owe it to them to pay for a replacement when this one dies.

But really, $130 for a battery and $80 for a charger? I still cannot get over this crap.
posted by InsanePenguin at 8:43 AM on January 8, 2010


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