MagSafe Power Bank from Scrap

Just a few short years ago, it was possible to find scrapped lithium batteries for free, or at least for very cheap. What most people at the time didn’t realize is that a battery with multiple cells might go bad because only one cell is bad, leaving the others ready for salvaging. Now it’s not a secret anymore, but if you can manage to get your hands on some there’s a lot of options for use. [ijsf] took a step further with this hack, taking a few cells from a Panasonic battery and wrangling them into a MagSafe-capable power bank for a Mac.

The real hack wasn’t scavenging batteries, however, it was getting the MagSafe to signal the computer to use power from the battery bank to run the computer only, and not to use any of that energy for charging the computer’s internal batteries. This is achieved by disabling the center MagSafe pin, which is the computer’s communication line to the power adapter. After that, the battery bank could be programmed to behave properly (a feat in itself for lithium batteries) and the power bank was successfully put into operation.

Not only was this hack a great guide for how to repurpose cells from a “dead” battery, it’s also an unparalleled quick reference for any work that might need a MagSafe connector. Of course, if you’re going to work with these chargers, make sure that you’re using one that isn’t a cheap clone.

21 thoughts on “MagSafe Power Bank from Scrap

  1. “so much more standard than my 2013 era Macbook’s battery pack, which I have had to replace on multiple occasions”

    Typing this on a 2013 Macbook Pro on its original battery pack, with 1200 cycles on it, which yields ~5-6 hours of operation. The SMC appears to think it has 70% of its capacity. I’ve got a “replace soon” caution under the battery menu and once in a while the low battery warning doesn’t come on before it goes into sleep (ie the SMC’s estimates are sometimes a little off), but I’ve been too lazy/cheap to drop the $200 on battery replacement since I get hours of use out of the original.

    Why is that people still feel a need to act like children and “dig” Apple?

    1. For the same reason people act like children and argue their chosen device is the best because reasons.

      My piece of shit £400 Acer has been running on the same battery for 4 years perfectly capable of meeting my requirements.

      Go Acer laptop. You managed to make it to 4 years before I had to tell anyone about you.

      1. Indeed. They know they are right and anyone who disagrees with them is evil and the enemy, to be ruthlessly destroyed by any means possible.

        Or is that sociologists….

    2. did he deliberately “dig” apple?, replacing laptop batteries is a common thing for some people, our use cases are different and some people really can wear down a battery in a year or two.

      his experience is probably as valid as yours in this case, trying to make it into an either/or is the real issue.

    3. Self-described Apple hater here. Let’s be fair, if we can.

      Credit where credit is due, Apple /does/ make things that look very pretty indeed, and their power supplies are friggin’ amazing on the inside. I actually recommend Apple chargers to people who need something to go between a wall socket and USB cable all the time. Also, Apple interfaces are feeping beautiful. They put a lot of thought into their products, inside and out, and I do want to give them credit for that.

      However, again, credit where credit is due — they also have a /very/ closed ecosystem for upgrades and repairs, which really bothers me, and that ecosystem is oriented towards the devices being consumables — use it up, throw it out, buy a new one. Apple devices — from computers on down — are purposely designed to be hard to repair. The current generation of iMacs have a glued-down foam seal around the seam where you get into ’em — you have to literally /cut them open/ to get inside. I have heard stories of iDevices laid out so that if you put the wrong screw in the wrong place, it’s a tenth of a millimeter too long and cuts traces that run underneath, bricking the device. The human eye cannot discern a 0.1mm difference in length between two screws… this stuff doesn’t happen by accident, either.

      As for upgrades… ever try adding a graphics card to a PowerMac? ;) good luck… I hope you know how to write drivers. I don’t think the Intel iMacs even /have/ expansion slots or capability to have anything like that except through USB or Thunderbolt or whatever — and, again, I hope you know how to write drivers…

      I’m also told that Apple computers are needlessly picky about things like memory timings. In a PC, the general rule with RAM is, if the RAM stick reasonably fits in the slot, the system will at least function with it in there, unless the capacity is too big for the system’s chipset. (Like putting a 4gb DDR2 stick in a netbook… DDR2-compatible netbooks really only go up to 2gb.) You might get poorer performance with one stick vs another, but the system won’t eg randomly hang on you. Macs, according to my local tech guy (who has most certainly seen his share of Apple desktops and laptops paraded through his doors) need specific RAM sticks with specific timings made specifically for Apple products, or you get stability issues. There’s really no excuse for that, electronically or otherwise, in this day and age.

      If Apple computers were as easy to operate on — and upgrade — as their PC counterparts, I would be /almost/ completely fine with That Fruit Company (well… we’d still have to have a talk about price gouging, but that’s for another day). Until then… well… I have a IIgs, and that’s about as much Apple as I can stand. I sincerely hope that that doesn’t bother you.

    1. Yes, you have to disassemble the packs into individual cells. Then, test the cells by charging them fully, and discharging them while recording their discharge rate(1C is usually good). Toss any cells that; get hot during charge or discharge, have voltage drop greater that .1V after left fully charged for a week, or are grossly below rated capacity.

      The ebike forum “endless sphere” has numerous article about it. A quick search will give you loads of info.

  2. The problem with this is that the next cell will soon go dead inside your carefully made pack. Then there is the hard fact that none of the cells balance very well in series. In parallel the dud will take out all the cells in that node and become the unexploded firebomb. It’s no longer a dud!

    The buzz on ES now seems to be Kobalt brand at Lowes, battery packs at good prices and at a local store. They have Samsung cells and not that cheep chickenshit including recycled laptop cells with polished ends and new shrink wrap with inkjet markings that “look real” and have a recent date. Shipping of loose cells and naked packs is highly complicated, but when they are inside a tested encased pack they are cheaper on sale with a drill or weed wacker included.

    1. >The problem with this is that the next cell will soon go dead inside your carefully made pack.

      Exactly. You are not using new cells, they have all been subject to the same stresses and the weakest one went kapoot. The others are probably not too far behind it. If you need power in an emergency or of you make your pack so it uses an old spring clip battery holder so you can swap them out fast and you have a lot of old cells, this might be something to play with, but if you are going to do anything you need to depend on, I would not use a battery pack made from recycled cells.

      1. New Battery Packs! Free Tool Included!

        It’s nonsense of course. The cost of replacement battery packs is grossly inflated in the same way as printer ink to the point where it’s cheaper to buy a new tool.

        1. printer ink is surprisingly expensive even when moving beyond that buisness model, easily reffilable proffesional printers still have expensive ink, even third party ink that is worth anything is fairly expensive.

          i think the ink is the most complicated and most researched part of any printer, the physical machine itself is beyond child’s play in comparison.

  3. I did find out that old batteries are slightly more reliable: lower capacity = longer life.
    Its feasible to recondition and balance the cells and I’ve done this to regain some lost capacity.

    Re. Magsafe, what about magtrix? the bare cells are a nightmare to connect but magnetic connectors might be adequate for a basic external pack.

    1. Because using one battery to charge another is not as efficient as using one battery to only power the computer. Disabling the communication pin disables battery charging on the laptop but still lets it use external power.

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