Power Macbook black from battery modified & connected to DC adapter?

Discussion in 'MacBook' started by tullpower, Aug 1, 2011.

  1. tullpower macrumors newbie

    Mar 22, 2010
    My Macbook 13" black, which has served me well throughout the years (better in fact then my superior specced PCs) has stopped working when connected to the A/C, and powers up only through battery power. It won't charge the batteries when connected to an A/C either. A brand new Apple A/C supply and a visit to the official Apple center revealed the logic board was busted, and needed to be replaced at a cost of almost EUR400.

    Since then, I bought two more batteries and an external charger, but since I use Windows a lot (.Net Developer) said batteries run out pretty fast, and constantly having to recharge / switch batteries is quite irritating.

    I came up with the crazy idea of modifiying one of my A1185 batteris to run from a DC supply in place of the 6 lithium cells inside. That way, I would avoid the need of swapping batteries every couple of hours and constantly charge them. While I am aware this is not for the faint hearted, I do think it's worth a try, since my only option would be a 400 euro repair bill.

    Does anyone here know how the 6 cells are wired to the batteries control circuit, and how it may be possible to connect a DC power supply in their place, maybe by using a series of voltage regulators? There should be no charge current coming back to charge the batteries, since the problem is that the macbook is not charging them in the first place, and it is not working from a magsafe power supply either, battery power being the only option.

    Any ideas and/or help from anyone who has disassembled and worked with apple A1185 batteries would be immensley appreciated!!

  2. unixperience macrumors regular

    Jul 21, 2010
    i can't help TOO much i haven't tried such a feat. but i do know the batteries have a chip in them that tells the computer how much life is in the battery, the temperature, the voltage, and current of the battery, if you don't have these things.. you could have some problems.
    I also know that the battery current varies immensely during use, so you'd need a fairly flexible supply with a wide current operating mode. I know my battery uses between 800-2200mA depending on what i'm doing, batteries can handle those surges much better than a power brick could. as such I would recommend if you can, trying to keep a few cells in still, 1-3 just for those surges, and in case you need to switch outlets or something.

    heres another idea, if you are thinking about building a crazy battery/ac adapter thing, maybe the cords from the charger socket to the board are bad (not the whole board) youd probably be savvy enough to connect the adapter directly to the port(bi-passing the actual port), and if it charges, you could probably replace wires, or concoct something to charge your computer. this could be easier than the battery idea, just a thought
  3. tullpower thread starter macrumors newbie

    Mar 22, 2010
    Thanks for your reply! The macbook controls the DC actively, and from what I've gathered, it is not a simple matter of bypassing the socket. In fact, the socket has its own small board, and is connected to the mainboard through an internal cable. According to the Apple service center though, the problem is not from the DC socket, but from the mainboard itself. Since it is jam packed with small surface mount components, finding the DC-in spots to bypass the faulty circuit and soldering additional wires to power it might actually be more difficult then converting a battery to run on DC power.

    If someone on this forum has the service manual or a technical diagram on how the battery, cells etc are wired, and can offer any help on how to connect a DC power supply to the battery, so as to power the Macbook from it, I would be eternally gratefull!


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