Any ideas for re-using old laptop batteries (18650)


I pulled apart an old laptop battery and have a number of G5 Sony/Fukushima 18650 cells (pretty sure they were produced pre-nuclear meltdown saga).

I have separated each of the batteries and am currently charging them on my newly purchased Lii-402 battery charger (although discovered interestly only can charge 3 at a time).

Just wondering if anyone has found any useful products which need 18650 batteries, or other projects which may utilise them.

Would appreciate and ideas.



  • +4


    It was actually Fukushima.

    • +1

      LMAO Fuk u too buddy … Joke.

      Thanks for correcting that for me.

      • No worries, Mat. ;)

        Names matter especially if they have a negative connotation.

  • +2

    I placed mine into powerbank enclosures. Can also use them to replace cordless vacuum batteries, if you are sure they actually run off the same type of cells.

  • +3

    I'm currently testing the capacity of the 18650 cells from 10 or so disassembled laptop batteries using a Lii-500

    some I will use in DIY powerbanks. like this one for US$3.23 delivered from aliexpress.

    some I was going to use to make a very large cell for solar storage and… that's as far as I got.

    • Ive also had a similar thought, if you use 7 li-ons in series you can use a 24v lead acid solar controller safely, described here. Just need a reliable way to balance the cells. In the end after reading a thread about a guy burning down a house with a homemade ebike battery (which has a bms) Ive had second thoughts

  • +4

    Flashlights? The cheap (<$10) "Cree" T6 lights pair nicely with an 18650.

    Or perhaps a power-bank enclosure like this with multiple voltage outputs - could be used, e.g. to keep a modem/router going for a while during a power outage. Paired with some jacks and a cable.

    • +1

      I've got a couple of those, filled with old laptop batteries.

      They work fine. That particular one will take 3 or 6 cells. Note that the USB isn't live all the time, you need to switch it to 5v. You can't charge your laptop & phone at the same time while travelling.

      There are nicer ones that don't have the clunky switches and hold more cells as well.

  • +1

    I've collected probably 8 or 9 old laptop batteries (so 24+ cells) but also haven't found a real good use yet. Just small projects replacing old Lipo batteries that have died. I'd use them in more projects if there was a cheap and easy way to charge & protect the cells from over-discharging; but as of yet I haven't found an AIO circuit that'd achieve this.

  • Electric toothbrushes? :-)

  • I was going to say powerbank. Coupled with a decent buck/boost converter, you can generate any voltage/current you need! (within reason)

    Like switchblade88 said, you need a protection circuit or you risk damaging them. The laptop battery should have a circuit board in it that does all of this.

  • +1

    Collect a few thousand more batteries and build your own DIY Tesla (electric car)

  • most vaping devices use these batteries if you're into that, usually like $10 a pop for batteries

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