Join 3,513 readers in helping fund MetaFilter (Hide)


Is my power supply dead?
August 17, 2008 3:05 PM   Subscribe

I just noticed that my Macbook's battery is running down even though the power supply is plugged in. Do I need a new power supply or could it be something I can fix?
posted by Andy Harwood to Computers & Internet (10 answers total) 1 user marked this as a favorite
 
Lithium batteries lose charge (at a slow rate) even if nothing is drawing power from them.
posted by Class Goat at 3:11 PM on August 17, 2008


That's very weird. I'm having exactly the same problem. It started a couple of days ago. (And Class Goat, it's not normal power loss. Basically, even when the computer is plugged in, the battery loses power as if it's not plugged in. The display on my computer says it's plugged in, and the little thing on the edge of the plug glows either orange or green like it's supposed to do when it's plugged in, but the battery still runs down. I jiggle the plug around, and at some point it seems to stop running down, but I can't tell if it's the jiggling that's making it stop or if it's random.)
posted by craichead at 3:22 PM on August 17, 2008


does this sound familiar ?

when I had that problem I found out there is a free exchange program for certain batteries. apple even paid for next-day ups and the return shipment. perhaps this is what's going on wth yours as well and if not do search the apple discussions. that forum is gold.

also: I have heard of a 17" mbp using nearly as much energy as it was able to charge while being used at full steam but it being discharged while plugged in sounds like a real problem on your end. are you sure there is power coming through that socket?
posted by krautland at 3:39 PM on August 17, 2008


Unless you're good at the innards of power supplies, you run a risk of hurting yourself (plus, I'm pretty sure the MBP power brick is not friendly to user tampering when it comes to putting it back together).

Take the computer, the battery, and the brick down to the Genius Bar at the Apple Store and explain your issue. Be polite but firm, and they'll probably say "oh, it's X part" and just give you a new one.

It sounds like a few things could be wrong--the wires in the cord on your power brick might be frayed and not making good contact, your computer's power management could be losing its mind due to issues with the onboard power management unit or the logic board, your battery could be crap. I don't know how good of an electronics hobbyist you are, but it might be easier and faster to just let Apple handle it in person.
posted by fairytale of los angeles at 4:15 PM on August 17, 2008


It could be your battery or it could be something you can fix. Does the display show that the battery is charging? If so, grab battery health monitor (available here) and see if the battery is actually taking any charge. If not, and it has few enough cycles on it, you may be eligible for a free replacement under one of several battery replacement programs from Apple. I was. You should also try resetting the System Management Controller which is responsible for charging etc.
posted by The Bellman at 4:21 PM on August 17, 2008


One thing I would say is note the small connector from the power supply (the small rectangular bit with the magnet that slips into the side of the laptop). Note if the light in it is sometimes going off even though your power supply is plugged in. If it's not, there's nothing wrong with the battery (or at least that's not the root of your problem), it's the power supply.

The last Macbook I had worked beautifully itself, but I went through two power cords in less than two years because they'd stop getting power to the laptop, eventually getting hot and melting right at the joint where the cord met the attachment. They would work for a time, then go out, then come back, out, back, etc. So it was a week or so before I figured out what was going on.
posted by el_lupino at 5:27 PM on August 17, 2008


One thing I would say is note the small connector from the power supply (the small rectangular bit with the magnet that slips into the side of the laptop). Note if the light in it is sometimes going off even though your power supply is plugged in. If it's not, there's nothing wrong with the battery (or at least that's not the root of your problem), it's the power supply.

Sorry, that should say, "If it is, there's nothing wrong with the battery..." Duh.
posted by el_lupino at 5:29 PM on August 17, 2008


For what it's worth, my MacBook is plugged in right now (and has been since last Tuesday) and the batter meter in the menu bar says the battery is at 97%. I noticed that the battery wasn't at the full 100% about two weeks ago, but I thought that it was a direct result of my battery being 20 months old.

I'll try to keep a closer watch on the battery meter to see if it actually charges to 100% after first being unplugged and then losing power or if the battery just does not charge to 100% in the first place.

As an aside, does anyone know if the battery monitor in OS X shows the percent charge of the original battery's capacity or the current capacity? The answer could differentiate the original poster's situation from my own.
posted by Third at 10:07 PM on August 17, 2008


If the power supply light is changing from green to red, it is topping off the battery, if it stays green the battery may not be able to take a charge any longer.
If you look in system profiler (spotlight it) under hardware, power, there is a Battery health info chart with a cycle count. If you're getting around 300, it may be the end of useful life for this battery. I tried finding the exact cycle # it will work until, but failed.
posted by ijoyner at 9:38 AM on August 18, 2008 [1 favorite]


It sounds like a few things could be wrong--the wires in the cord on your power brick might be frayed and not making good contact

I'm betting on this. The cord on my G3 MB frayed until the (copper?) innards of the wire were showing, near the end that plugs into the computer. At first, it was just a cosmetic thing, but it got so bad that it stopped charging the computer (and delivered a rejuvinating shock each time I brushed against the bare wire!)

At my buddy's house last night, I noticed his cord (for the most recent gen MB, with the magnetic plug) was also frayed in the same place.
posted by andromache at 11:25 AM on August 18, 2008


« Older What is this study? A study th...   |  How come my couch makes everyo... Newer »
This thread is closed to new comments.