Ugly upgrade keeps the tunes playing longer

[Sam] picked up a Sansa Clip audio player to listen to some tunes while working on projects. He liked the fact that he could run the Rockbox alternative firmware on the device, but thought the 15 hour battery life needed some improving. He swapped out the stock cell with a larger Lithium cell for a long life of 50-60 hours. It’s an upgrade fom 300 mAh to 1100 mAh, but as you can see, the size of the replacement made for some interesting case modification.

The battery swap required more than just taking one battery out and putting in the other. [Sam] is using a cellphone battery as the replacement and he didn’t want to have issues with the internal circuitry. He took the cell out of its plastic enclosure, removing the circuit board in the process. That PCB is the charging circuit, which he replaced with the one from the stock battery. After insulating the cell with a layer of Kapton tape he soldered it to the MP3 player and did his best to adhere all the parts to each other.

Sure, its ugly, but that makes it right at home on the work bench.


  1. Dave says:

    That PCB isn’t the charging circuit, it’s the battery protection circuit. It prevents over-charging and over-discharging, by opening the circuit for charge or discharge as necessary.
    Absolutely essential to keep one in circuit, but very surprising that the new cell didn’t have its own. Very few manufacturers will ship Li-ion cells without one, as they’re liable to explode…

    • AFAIK Most Li-Ion Cell Phone batteries dont come with a protection circuit. The Cell Phone manufacturers probably customize it,and the ‘protection circuit’ is inside some SoC or PMIC on the cell phone itself .

      • macona says:

        All cell phones that have removable batteries have a protection circuit built onto the battery. That is the only way for the pack to be disabled if it is discharged below 2.7v.

        In a shrink wrapped cell it is often part of the connector and in plastic cased cells it is often a little board on the end of the battery.

        If the battery is soldered to the board the battery management IC is usually part of the main board.

      • I once had taken apart a Nokia BL-5C battery clone ….Could’nt find any sort of circuitry in there….the cell was directly connected to the terminals….Might have been ‘coz it was a cheap clone ,the circuit might be present in the original ones i guess……Will open up an original one.

      • nes says:

        I have a whole stack of genuine cellphone batteries. They all have the protection PCB. It would be really foolish of the phone manufacturers to ship a removable battery without one fitted in case you decide to charge it outside the phone and it explodes.

        I guess the one you found was a knock-off, in which case it was pretty irresponsible. Wouldn’t like to have one catch fire in the house or in my pocket.

      • Nordmann says:

        But people do have keys and other metal objects in their pockets that can short out a battery. without any kind of protection circuitry in the battery would lead to a fire in your pocket..

  2. knightvoyager says:

    I LOVE rockbox,and this case mod is awesome!
    I’ve had three gigabeats running rockbox so far, I literally wore them all out. (specifically the audio jacks on the mobo)

  3. Haku says:

    One day I predict seeing a hack involving an old 80s brick phone which has had the guts replaced with a large battery capacity and a modern day phone, giving a standby battery life you count in weeks (months?) not days.

  4. Dan J. says:

    OK, cool hacking chops, but if it’s only being used on a workbench, why not just get rid of the battery and run it from a power supply?

    • eyrieowl says:

      I agree. That said, I think were I trying to make it battery powered, I’d be more inclined to build a battery powered enclosure which attaches to the unit’s charging jack, leave the original unit more…svelte.

  5. tehkillerbee says:

    I have done something similar (although much prettier) to my iPod video.

    I upgraded the battery to the biggest battery i could fit behind the thin 80GB 5mm harddrive I installed when the old two platter 80GB broke. I found a 1800mAh battery and it fits perfectly, although its not as long as the harddrive itself. The ipod now lasts much, much, MUCH longer, and it still looks stock! There is actually room to spare for a headphone amplifier or transmitter maybe?

    • Sven says:

      I have an old Ipod nano G2, it’s the exact same size as the lipo cells in most macbook batteries. i just taped one of those to the back of it. now it’s double the size and has several days battery time :P

      However the charging circuit was not dimensioned to charge a cell of that size so it burned out…

  6. echodelta says:

    Does the Sansa Clip with the round control and button inside, work with Rockbox. On their site it wasn’t clear weather it would or not.
    I am all for hacking big battery on to silly slim devices, for weeks of playtime.

  7. JB says:

    Good hack. Did it to my old Sansa and I used a power module that was produced by my previous employer. Disabled the controller and run the (protected) lithium battery to the Sansa wires. No need for the internal Sansa charging circuit as the module had its own. Much better looking since it is a finished product. I tapped holes and screwed the Sansa back in for a solid mount.

  8. superbrainak says:

    I also did this with a 2ndGen iPod(also running rockbox) whos battery would last 1min. I took a 1150mAh cellphone battery whos circuit was corroded, took off the old one and replaced it with the circuit to the ipods batt. and glued it to the back with the wire going between the metal back and plastic front. the battery lasts but it cant source enough power so if you turn up the backlight the voltage drops so something is messed up.

  9. Chris C. says:

    That’s hideous. Plastic boxes, Altoids tins, and so on are cheap (or free). Just attach one to the back.

  10. bunedoggle says:

    Just did this to my daughters cheap MP3 player.

    First thing I thought was, better not try to take this on an airplane.

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