Charger working intermittently / LED blinking 3x on startup?

Discussion in 'MacBook' started by nerd05, Mar 21, 2010.

  1. nerd05 macrumors newbie

    Apr 5, 2004
    I acquired a Unibody MacBook that experienced a little water damage. The logic board was definitely shot, so I replaced that yesterday and initially the machine was working like a champ, save for a few issues:

    1. The machine tries charging my battery, but eventually gives up and decides that there is no battery in the machine (there is a battery in there, and it shouldn't be dead yet, should it?)

    2. I've been experiencing an issue in which the MacBook and charger aren't getting along. I've got two different chargers, both of which work on my pre-Unibody MBP consistently but sometimes I'll plug one into the MacBook and get no light, and in other cases I'll plug it in and get just a very faint green light. In either case, the machine won't start up. I usually tinker with the machine for a few minutes, taking the back plate off and checking connections, waiting a few minutes, and it's back up again.

    3. Before the machine starts up, the LED blinks three times. I initially thought this was just a blink pattern to notify the user that the logic board doesn't have a serial number yet, but I've run the serializer and entered a SN in, and it still does that. Is this normal for these Macs?

    I know that these MacBooks are a little more intricately tied to the battery than previous Macs. Does anyone think the above problems (at least 1 and 2) would be solved by a replacement battery? Or does it sound like something else is wrong (perhaps the DC in board)? I've never heard of anyone needing to replace a Magsafe DC in board (and from their low prices online, I'm led to believe that they rarely fail).
  2. Pax macrumors 6502a

    Dec 12, 2003
    I'm not a massive expert but this may be of help

    DC in board

    Someone on here a couple of weeks ago had a problem which we (not me - someone clever!) thought was a DC in board. Try searching. The symptoms were different, but similar to yours.

    I think also that people with "failure to recognise battery" often get a new logic board from Apple. But note - when they say this, it might be an Apple Genius saying logic board as a catch-all for some kind of PCB inside the Mac ie could be a DC in board.


    Does the Mac recognise the battery? In System Profiler under the "Power" tab it should give you some info like a serial number and also say Battery Installed "Yes" and Condition which will be one of Good -> Normal -> Check battery -> Replace battery. The last two are bad. Also down at the bottom it should say charger connected etc.

    The battery does have a fair bit of logic in it which might have been fried in the water damage.

    Also I understand the logic is fail safe and will "destroy" the battery and prevent it ever charging again if it has been deep discharged (perhaps as part of a short circuit). I believe the idea is that deep discharging causes metal to precipitate inside the cells and can cause explosions etc if recharging occurs.

    But System Profiler should tell you what you need to know. It's not always infallible though.
  3. nerd05 thread starter macrumors newbie

    Apr 5, 2004
    Well, I did get it working a little bit, though there are some issues. After leaving it plugged in for a long time, the battery finally did slowly charge (in about 7-8 hours to full). However, usually when I plug the charger in, I don't get the light turning green. On some chargers it turns a very very pale green. But the battery was low about 36 hours ago after I tested its longevity so I plugged it in. The MacBook was able to run off of the charger, but it wasn't charging anything at the time (the menu bar said "not charging"). However, I looked at it today after work and the battery is charged (though the charger is again at a dim green)

    I assume the reason it wouldn't turn on at all while plugged in before was because the Unibody MacBooks are a little more reliant on having a battery plugged in.

    If I'm able to get enough power for the Mac to run while plugged in, just not charge consistently, does this sound like the DC in board? Is there anything else it could be? It looks like the cable connecting the battery to the logic board is just a cable and nothing more, so that leaves DC in board.

    I can't complain much, though, DC in boards are relatively inexpensive. :)
  4. Pax macrumors 6502a

    Dec 12, 2003
    Discharge it to about half way
    Plug in the charger
    look in System Profiler under Power
    It will tell you the amperage going into the battery.
    On a healthy Mac with a nearly empty battery it should be around 1300 mA
    That means it can charge a 5000 mA battery in 3 hours or so.
    The charge current tails off as it reaches full

    If it's not >1000 mA I'd say you have a DC in problem
  5. nerd05 thread starter macrumors newbie

    Apr 5, 2004
    Amperage is 131. Looks like a new DC in board is in order.
  6. Pax macrumors 6502a

    Dec 12, 2003
    Sounds like it.
    131 mA is peanuts.

    What does it say for battery voltage? Is it possible you have a sensor malfunction which thinks the battery is nearly charged and just trickles the current?

    Post your System Profiler -> Power readings here when running on battery, about 1/2 full

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